Prognostic value of adenosine stress perfusion cardiac MRI with late gadolinium enhancement in an intermediate cardiovascular risk population

Background

The high diagnostic accuracy of adenosine stress cardiac magnetic resonance (AS-CMR) for detecting coronary artery stenoses, with high sensitivity and specificity, is well documented. Prognostic data, particularly in non-low risk study populations and for greater than 12 months of follow up, is however lacking or variable in its findings. We present prognostic data, in an intermediate cardiovascular risk cohort undergoing adenosine stress perfusion CMR, over approximately 2 years of follow up.

Methods

The study population comprised 362 patients referred for a clinically indicated stress CMR and included patients with proven coronary artery disease (CAD; n = 157) or unknown CAD status, yet an intermediate cardiovascular risk profile (n = 205). Perfusion imaging was performed at stress (adenosine 140 μg/kg/min) and rest on a 1.5 T system. Patient records and state-wide hospital databases were reviewed. Major adverse cardiac events — death, myocardial infarction, revascularisation or ischaemic hospitalisation — were evaluated over a median follow up of 22 months.

Results

Of the 362 cases, 90 had a stress perfusion CMR positive for ischaemia and experienced a MACE rate of 24%. Of the 272 negative CMR scans, 225 were also negative for late gadolinium enhancement, and in this group MACE was encountered in only 6 (2.7%) patients. Accordingly a negative stress CMR afforded a freedom from MACE of 97.3%. Freedom from death/myocardial infarction was 99.6%.

Conclusions

In patients with confirmed coronary artery disease or at intermediate risk for cardiovascular events, a negative stress perfusion CMR is associated with an excellent prognosis over nearly 2 years of follow up.     

Edema and fibrosis imaging by cardiovascular magnetic resonance: How can the experience of Cardiology be best utilized in rheumatological practice?

Objectives

CMR, a non-invasive, non-radiating technique can detect myocardial oedema and fibrosis.

Method

CMR imaging, using T2-weighted and T1-weighted gadolinium enhanced images, has been successfully used in Cardiology to detect myocarditis, myocardial infarction and various cardiomyopathies.

Results

Transmitting this experience from Cardiology into Rheumatology may be of important value because: (a) heart involvement with atypical clinical presentation is common in autoimmune connective tissue diseases (CTDs). (b) CMR can reliably and reproducibly detect early myocardial tissue changes. (c) CMR can identify disease acuity and detect various patterns of heart involvement in CTDs, including myocarditis, myocardial infarction and diffuse vasculitis. (d) CMR can assess heart lesion severity and aid therapeutic decisions in CTDs.

Conclusion

The CMR experience, transferred from Cardiology into Rheumatology, may facilitate early and accurate diagnosis of heart involvement in these diseases and potentially targeted heart treatment.     

Comparison of cardiac magnetic resonance with gated SPECT for evaluation of left ventricular function and volumes in patients with severe and multiple myocardial perfusion defects

Objectives

Gated SPECT is an accurate technique for assessment of myocardial perfusion (MP), left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). However recent studies have concluded that there are large discrepancies in assessment of LVEF and volumes by gated SPECT in patients with multiple severe myocardial perfusion defects. We sought to investigate the correlation between LVEF and volumes calculated by gated SPECT and cardiac magnetic resonance (CMR) in patients with severe multiple perfusion defects who are referred for CMR.

Methods

Twenty-nine patients (20 male and 9 female, mean age: 63 years ± 11) with multiple severe fixed perfusion defects (mean 5 ± 3 segments) were referred to undergo CMR. The average time between CMR and SPECT was 4 weeks. LVEF, EDV, and ESV were derived automatically from gated SPECT. In the CMR studies, the endocardial and epicardial borders were delineated manually in the short axis planes to calculate the LVEF and volumes.

Results

The different parameters were compared using linear regression, and correlation coefficients were calculated. Substantial correlation was found between CMR and gated SPECT for EDV: r = 0.7, p < 0.001. Moderate correlation between CMR and gated SPECT for LVEF: r = 0.5, p < 0.007 and ESV r =0 .53, p < 0.003.

Conclusion

Our data showed that the gated SPECT correlates substantially with MRI for measurement of EDV and moderately for ESV and LVEF in patients with multiple and severe perfusion defects. Thus, when accurate measurement is required, cardiac MRI is recommended.     

Cardiovascular magnetic resonance imaging in asymptomatic patients with connective tissue disease and recent onset left bundle branch block

Background–aim

Recent LBBB in connective tissue diseases (CTDs) is challenging, due to high incidence of underlying pathology that may remain undetected, due to limitations of imaging tests. We hypothesized that cardiovascular magnetic resonance (CMR) may be of diagnostic value in CTDs with recent LBBB and normal echocardiogram.

Patients–methods

26 CTDs, aged 32 ± 7 yrs (19 F) and 26 controls without CTDs, aged 60 ± 4 yrs (10 F) with recent LBBB and normal echo were evaluated by CMR. The CTDs included 6 sarcoidosis (SRC), 4 systemic sclerosis (SSc), 6 systemic lupus erythematosus (SLE), 6 rheumatoid arthritis (RA) and 4 inflammatory myopathies (IM). CMR was performed by 1.5 T. LVEF, T2 ratio (oedema imaging) and late gadolinium enhancement (LGE) (fibrosis imaging) were evaluated. Acute and chronic lesions were characterised by T2 > 2 and positive LGE and T2 < 2 and positive LGE, respectively. According to LGE, lesions were characterised as diffuse subendo-, subepicardial/intramural not following and subendocardial/transmural following the distribution of coronaries, indicative of vasculitis, myocarditis and myocardial infarction, respectively.

Results

CTDs were younger (p < 0.001), with higher incidence of abnormal CMR (42.31 vs 30.77%, p = NS), including dilated cardiomyopathy (11.54%), diffuse subendocardial fibrosis (11.54%), myocardial infarction (7.69%) and acute myocarditis (11.54%) vs dilated cardiomyopathy (19.23%), myocardial infarction (7.69%) and acute myocarditis (3.85%), detected in non-CTDs.

Conclusions

In CTDs with recent LBBB, CMR documented acute and chronic cardiac pathology, particularly myocarditis. CMR should be considered as an adjunct to conventional diagnostic workup in both patient groups, more so in CTDs.     

Right atrial volume and phasic function in pulmonary hypertension

Background

Few studies have focused on right atrial (RA) structure and function in pulmonary hypertension (PH). We sought to evaluate RA volume and phasic function using cardiac magnetic resonance (CMR), and to examine their clinical relevance in PH.

Methods

We prospectively studied 50 PH patients and 21 control subjects. RA volume and indices of phasic function (reservoir volume, ejection fraction [EF], and conduit volume) were evaluated by CMR.

Results

Maximum RA volume index was significantly higher in PH patients (56 [44–70] ml/m²) than in controls (40 [30–48] ml/m²) (p < 0.001). Reservoir volume index was significantly lower in PH than in controls (p < 0.001), but conduit volume index was higher in PH than in controls (p = 0.008). RA EF was similar when comparing the two groups (p = 0.925). Interestingly, RA EF was increased in PH patients with WHO functional class III patients as compared with controls (p < 0.001) but was reduced in advanced PH patients with WHO functional class IV (p < 0.01). Maximum RA volume and RA EF significantly correlated with pulmonary hemodynamic indices, atrial and brain natriuretic hormone levels, and CMR-derived right ventricular indices. By contrast, RA reservoir volume correlated with cardiac index and 6-minute walk distance.

Conclusions

PH is associated with increased size, decreased reservoir function, and increased conduit function of the right atrium. RA systolic function indicated by RA EF increases in patients with mild to moderate PH but decreases in patients with advanced PH. Varying associations between RA indices and conventional PH indices suggest their unique role in the management of PH.     

Impact of new task force criteria in the diagnosis of arrhythmogenic right ventricular cardiomyopathy

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy that can lead to sudden cardiac death. The diagnostic criterion has recently been revised and through the use of cardiac magnetic resonance (CMR) imaging this study aimed to assess the clinical impact of comparing the original 1994 task force (TF) criterion to the revised 2010 criterion.

Methods

We evaluated 173 consecutive CMR scans of patients referred with clinical suspicion of ARVC between 2008 and 2011. We then compared the prevalence of major and minor CMR criteria by applying the two criteria.

Results

Using the 1994 TF criterion, 13 (7.5%) patients had definite, 11 (6.4%) had borderline, and 39 (22.5%) had possible ARVC. Using the 2010 TF criterion, 10 (5.8%) patients had definite, 1 had borderline, and 7 had (0.04%) possible ARVC. With the 1994 criterion, 81 patients satisfied CMR criterion, of which 36 (44%) had major and 45 (56%) had minor criteria. Upon reclassification with the revised criterion, 61 of the 81 patients were not assigned any criteria, even though many patients had significant risk factors. The negative predictive values (NPV) for both CMR criteria were 100% but the positive predictive values (PPV) for combined CMR major or minor criteria improved from 23% to 55%.

Conclusions

Revision of the criterion has enhanced the diagnostic capabilities of CMR but has resulted in a large cohort of patients not classified. In these patients, there is presently no official consensus on imaging or clinical strategy for surveillance of the evolution of pathology over time.     

Comprehensive Prognosis Assessment by CMR Imaging After ST-Segment Elevation Myocardial Infarction

Background

Although the prognostic value of findings from cardiac magnetic resonance (CMR) imaging has been established in single-center center studies in patients with ST-segment elevation myocardial infarction (STEMI), a large multicenter investigation to evaluate the prognostic significance of myocardial damage and reperfusion injury is lacking.

Objectives

The aim of this study was to assess the prognostic impact of CMR in an adequately powered multicenter study and to evaluate the most potent CMR predictor of hard clinical events in a STEMI population treated by primary percutaneous coronary intervention (PCI).

Methods

We enrolled 738 STEMI patients in this CMR study at 8 centers. The patients were reperfused by primary PCI <12 h after symptom onset. Central core laboratory–masked analyses for quantified left ventricular (LV) function, infarct size (IS), microvascular obstruction (MO), and myocardial salvage were performed. The primary clinical endpoint of the study was the occurrence of major adverse cardiac events.

Results

Patients with cardiovascular events had significantly larger infarcts (p < 0.001), less myocardial salvage (p = 0.01), a larger extent of MO (p = 0.009), and more pronounced LV dysfunction (p < 0.001). In a multivariate model that included clinical and other established prognostic parameters, MO remained the only significant predictor in addition to the TIMI (Thrombolysis In Myocardial Infarction) risk score. IS and MO provided an incremental prognostic value above clinical risk assessment and LV ejection fraction (c-index increase from 0.761 to 0.801; p = 0.036).

Conclusions

In a large, multicenter STEMI population reperfused by primary PCI, CMR markers of myocardial damage (IS and especially MO) provide independent and incremental prognostic information in addition to clinical risk scores and LV ejection fraction. (Abciximab i.v. Versus i.c. in ST-elevation Myocardial Infarction [AIDA STEMI]; NCT00712101).     

Association between neutrophil–lymphocyte ratio and impaired myocardial perfusion in patients with known or suspected coronary disease

Objective

To determine whether an elevated neutrophil–lymphocyte ratio (NLR) is associated with chronically impaired myocardial perfusion in patients with known or suspected coronary disease.

Background

Elevated NLRs are positively associated with cardiac events, anatomic coronary disease, and myocardial infarct size. However, no study has evaluated the association between NLR and chronically impaired myocardial perfusion.

Methods

This study included 683 patients undergoing cardiac positron emission tomography (PET) with a calculable NLR within 90 days of PET. The primary outcome was myocardial perfusion defect size measured in percent of left ventricular mass (%LV60).

Results

NLR was independently associated with %LV60 when analyzed as both a continuous and binary outcome (p < 0.001). Individuals with NLR above the 90th percentile had a 5-fold increased likelihood of significant perfusion defects compared to individuals with NLR between the 10th and 25th percentiles (Odds ratio = 4.7, p < 0.001).

Conclusion

An elevated NLR demonstrated strong associations with myocardial perfusion.     

Osteoprotegerin in ST-elevation myocardial infarction: Prognostic impact and association with markers of myocardial damage by magnetic resonance imaging

Background/Objectives

For osteoprotegerin (OPG), a cytokine of the tumor necrosis factor superfamily, the prognostic impact in stable coronary artery disease and acute coronary syndromes has been shown recently. In acute ST-elevation myocardial infarction (STEMI) data on the correlation to myocardial damage by cardiac magnetic resonance imaging (CMR) or clinical outcome are lacking.

Methods

We studied 221 consecutive patients with acute STEMI undergoing primary percutaneous coronary intervention (PCI) within 12 h after symptom onset. Serum levels of OPG were determined from samples collected before PCI (OPG0), at 24 (OPG1) and 48 h (OPG2) after reperfusion. CMR studies for assessment of infarct size, reperfusion injury/microvascular obstruction and myocardial salvage were performed within one week after infarction. Long-term clinical follow-up for major adverse cardiovascular events (MACE), defined as death, myocardial infarction, or new onset of congestive heart failure, was performed 18.2 (interquartile range of 9.2–21.2) months after the index event.

Results

OPG levels ≥ 75th percentile were associated with significantly larger infarcts, lower myocardial salvage index and greater extent of microvascular obstruction in CMR as compared to OPG levels < 75th percentile. The MACE rate for patients with OPG levels in the highest quartile was also significantly higher. In a multivariable model adjusted for known risk factors, OPG1 as a continuous variable was independently predictive for MACE.

Conclusion

OPG serum levels collected 24 h after infarction are independent predictors of MACE in acute STEMI patients. High OPG levels are associated with a greater extent of myocardial damage and lower myocardial salvage by CMR.     

Gated-SPECT de perfusión miocárdica como técnica complementaria de la resonancia magnética para pacientes con infarto de miocardio crónico

Introduction and objectives

The aim of this study was to compare magnetic resonance and gated-SPECT myocardial perfusion imaging in patients with chronic myocardial infarction.

Methods

Magnetic resonance imaging and gated-SPECT were performed in 104 patients (mean age, 61 [12] years; 87.5% male) with a previous infarction. Left ventricular volumes and ejection fraction and classic late gadolinium enhancement viability criteria (<75% transmurality) were correlated with those of SPECT (uptake >50%) in the 17 segments of the left ventricle. Motion, thickening, and ischemia on gated-SPECT were analyzed in segments showing nonviable tissue or equivocal enhancement features (50%-75% transmurality).

Results

A good correlation was observed between the 2 techniques for volumes, ejection fraction (P<.05), and estimated necrotic mass (P<.01). In total, 82 of 264 segments (31%) with >75% enhancement had >50% SPECT uptake. Of the 106 equivocal segments (50%-75% enhancement) on magnetic resonance imaging, 68 (64%) had >50% uptake, 41 (38.7%) had normal motion, 46 (43.4%) had normal thickening, and 17 (16%) had ischemic criteria on SPECT.

Conclusions

A third of nonviable segments on magnetic resonance imaging showed >50% uptake on SPECT. Gated-SPECT can be useful in the analysis of motion, thickening, and ischemic criteria in segments with questionable viability on magnetic resonance imaging.Full English text available from:www.revespcardiol.org/en     

Evaluation and Management of Cardiac Tumors

Purpose of review

Our purpose is to discuss the importance of multimodality imaging in the assessment of cardiac tumors and management. We have compiled a recent review of the scientific literature and embedded our clinical pathways and recommendations based on data and clinical experience.

Recent findings

The use of contrast echocardiography in the assessment of cardiac masses has been shown to be helpful in distinguishing tumor from thrombus. Deformation imaging of cardiac tumors has been shown to differentiate better rhabdomyomas from fibromas in pediatric patients. Cardiac MRI (CMR) appears to be helpful in determining whether cardiac tumors are benign or malignant by identifying presence of infiltration, uptake of contrast in first pass perfusion and gadolinium enhancement. Patients with evidence of cardiac metastases by CMR show similar survival to stage IV cancer without cardiac metastases. In our institution, we use a standardized approach for the evaluation of cardiac masses, which includes multimodality imaging in the appropriate clinical context. The autotransplantation surgical technique has shown some promise in improving survival in patients with primary cardiac sarcomas. In our institution, we do not routinely recommend anticoagulation for “tumor-thrombus” in renal cell carcinoma due to risk of bleeding from primary tumor.

Summary

Cardiac masses are often found incidentally, but sometimes can present with cardiovascular symptoms due to obstruction and valvular dysfunction, which may prompt imaging. It is important to determine whether the mass is a normal variant, imaging artifact, vegetation, thrombus, or tumor. Transthoracic echocardiography is ideally suited to be the initial imaging modality because of the portability, wide availability, lack of radiation, and relatively low cost. The gold standard cardiac imaging technique to distinguish tumor from thrombus is contrast enhanced CMR with prolonged inversion time. Advantages of CMR when compared to echocardiography regarding characterization of cardiac tumors are as follows: larger field of view, better spatial resolution, better tissue characterization, lack of attenuation, and ability to image at any prescribed plane. Primary and secondary cardiac tumors have particular characteristics in echocardiography and CMR. Imaging of cardiac tumors plays an important role in establishing a diagnosis and in planning management.

     

Prognostic value of cardiovascular magnetic resonance in patients with suspected arrhythmogenic right ventricular cardiomyopathy

Background

Early recognition and accurate risk stratification are important in the management of arrhythmogenic right ventricular cardiomyopathy (ARVC). Identification of predictors of outcome by cardiovascular magnetic resonance (CMR) in patients undergoing evaluation for ARVC is limited. We investigated the predictive value of morphological abnormalities detected by CMR for major clinical events in patients with suspected ARVC.

Methods

We performed a longitudinal study on 369 consecutive patients with at least one criterion for ARVC. Abnormal CMR was defined by the presence of one of the following: increased right ventricular (RV) volumes, reduced RV ejection fraction, RV regional wall motion abnormalities, myocardial fatty infiltration, and myocardial fibrosis. The end-point was a composite of cardiac death, sustained ventricular tachycardia, ventricular fibrillation, and appropriate ICD discharge.

Results

Twenty patients met the composite end-point over a mean follow-up of 4.3 ± 1.5 years. An abnormal CMR was an independent predictor of outcomes (p < 0.001). The presence of multiple abnormalities heralded a particular high risk of events (HR 23.0, 95% CI 5.7–93.2, p < 0.001 for 2 abnormalities; HR 35.8, 95% CI 9.7–132.6, p < 0.001 for 3 or more abnormalities). The positive predictive value of an abnormal CMR study was 21.0% for an adverse event, whilst the negative predictive value of a normal CMR study was 98.8% over the follow-up period.

Conclusions

CMR provides important prognostic information in patients under evaluation for ARVC. A normal study portends a good prognosis. Conversely, the presence of multiple abnormalities identifies a high risk group of patients who may benefit from ICD implantation.     

Improvement of myocardial function and perfusion after successful percutaneous revascularization in patients with chronic total coronary occlusion

Background

Percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) of a coronary artery can provide benefits in terms of myocardial function and survival but the procedure is complex and the success rate is relatively low. To assess these benefits, myocardial function, ischemia and viability should be clearly determined by means of a reliable diagnostic test. This study aimed to assess ventricular function and myocardial ischemia before and after PCI for CTO using cardiac magnetic resonance (CMR). NYHA functional class was also assessed before and after PCI.

Methods and results

CMR studies were performed in 43 consecutive patients (7 females; aged 64 ± 9.6 y.o.) with CTO scheduled for PCI and repeated 6 months post-PCI. PCI was successful in 33 (77%) of them. In this group CMR had shown inducible perfusion defects in 26 (79%) before PCI, while they were observed in 10 (30%) post-PCI CMR study (p < 0.001). The number of segments showing inducible perfusion defect (3.4 ± 2 prevs. 2.9 ± 4.5 post-PCI, p = 0.002) was significantly reduced in this group. Regional contractile function of segments showing viability also improved significantly in the group with successful CTO PCI compared to the group with an unsuccessful procedure. NYHA functional class for angina also improved in patients with successful revascularization while it remained unchanged in the group with unsuccessful procedures.

Conclusions

A successful CTO PCI leads to a reduction in inducible myocardial ischemia and to an improvement in regional wall motion, which results in clinical improvement.     

Incremental value of cardiac imaging in patients presenting to the emergency department with chest pain and without ST-segment elevation: a multicenter study

Background

We hypothesized that imaging of regional myocardial function (RF) and perfusion (PER) will add incremental value for both diagnosis and short-term prognosis to routine demographic, clinical, and electrocardiographic findings in patients presenting to the emergency department (ED) with chest pain and without ST-segment elevation on the electrocardiogram.

Methods

We compared contrast echocardiography (CE) with gated single-photon emission computed tomography (SPECT) for this purpose. Both CE and SPECT readings included separate and composite assessments of both RF and PER. Adverse events in the first 48 hours after ED presentation included acute myocardial infarction, emergent revascularization, and cardiac-related death.

Results

Concordance between CE and SPECT was 77% (73% to 82%) for all territories, with a higher concordance for the anterior wall of 84% (78% to 89%). Of the 203 patients recruited for the study, 38 (19%) had a cardiac event within 48 hours of ED presentation: 21 had acute myocardial infarction, 16 underwent an urgent revascularization procedure, and 1 died. In multivariate logistic regression models, the number of abnormal segments on CE and SPECT were significant predictors (P < .05) of cardiac events. The composite scores on CE provided 17% incremental information (P = .009, n = 203) and gated SPECT provided 23.5% additional information (P = .020, n = 163) for predicting cardiac events compared with routine demographic, clinical, and electrocardiographic variables. RF and composite evaluation was superior on SPECT compared with CE, whereas PER alone was not.

Conclusions

Cardiac imaging of RF and PER at the time of ED presentation offers substantially greater diagnostic and prognostic information for early cardiac events in patients presenting to the ED with chest pain and no ST elevation than does the routine demographic, clinical, and electrocardiographic assessment.     

The emerging role of cardiac computed tomography for the assessment of coronary perfusion: a systematic review and meta-analysis

Background

Computed tomography perfusion (CTP) is an emerging method which, coupled with the anatomical detail afforded by cardiac computed tomographic angiography (CCTA), may allow for determination of both structural and physiologic significance of coronary stenoses with a single imaging modality. This study was designed to execute a systematic review/meta-analysis to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTP as compared with reference standards for detection of significant coronary artery stenoses and impaired perfusion.

Methods

A systematic review identified 13 out of 4368 studies allowing a calculation of sensitivity, specificity, PPV, and NPV on a per patient or per vessel or per segment basis using radionuclide myocardial perfusion imaging (MPI), conventional coronary angiography (CCA), magnetic resonance perfusion imaging (MRPI), or fractional flow reserve (FFR) as the reference standard. Meta-analyses of results were carried out using random effects modelling.

Results

Most studies used a maximal vasodilator stress protocol with adenosine, provided information mainly on a per vessel basis, and used myocardial perfusion imaging or CCA as the reference standard. Of the studies comparing combinations of both anatomical and functional imaging, the most rigourous standard was CCA/FFR. Compared with the latter, CCTA/CTP had sensitivity, specificity, PPV, and NPV of 81%, 93%, 87%, and 88%, respectively.

Conclusions

CTP shows promise as an adjunct to CCTA, potentially allowing determination of both structural and physiologic significance with a single imaging modality.     

Safety and diagnostic accuracy of stress cardiac magnetic resonance imaging vs exercise tolerance testing early after acute ST elevation myocardial infarction

Objective

To determine the safety and diagnostic accuracy of adenosine‐stress cardiac magnetic resonance (CMR) perfusion imaging early after acute ST elevation myocardial infarction (STEMI) compared with standard exercise tolerance testing (ETT).

Design and setting

Cross sectional observational study in a university teaching hospital.

Patients

35 patients admitted with first acute STEMI.

Interventions

All patients underwent a CMR imaging protocol which included rest and adenosine‐stress perfusion, viability, and cardiac functional assessment. All patients also had an ETT (modified Bruce protocol) and x ray coronary angiography.

Main outcome measures

Safety and diagnostic accuracy of adenosine‐stress perfusion CMR vs ETT early after STEMI in identifying patients with significant coronary stenosis (⩾70%) and the need for coronary revascularisation. Also, to determine if CMR can distinguish between ischaemia in the peri‐infarct zone and ischaemia in remote myocardium.

Results

CMR imaging was well tolerated (all patients completed the protocol) and no complications occurred. CMR was more sensitive (86% vs 48%, p = 0.0074) and more specific than ETT (100% vs 50%, p<0.0001) for detecting significant coronary stenosis, and more sensitive for predicting revascularisation (94% vs 56%, p = 0.039). Inducible ischaemia in the infarct related artery territory was seen in 21 of 35 patients and was associated with smaller infarct size and less transmurality of infarction.

Conclusions

Adenosine‐stress CMR imaging is safe early after acute STEMI and identifies patients with significant coronary stenosis more accurately than ETT.     

Transient Myocardial Tissue and Function Changes During a Marathon in Less Fit Marathon Runners

Background

Although regular physical activity improves health, strenuous exercise might transiently increase cardiac risk. Training and fitness might provide protection.

Methods

We prospectively studied 20 recreational marathon runners without known cardiovascular disease or symptoms: at peak training before, immediately after, and 3 months after a 42.2-km marathon. Changes in global/segmental myocardial function, edema, resting perfusion, and fibrosis were measured.

Results

At peak training, runners exercised 8.1 ± 2.3 hours and 62 ± 18 km per week with mean maximal oxygen consumption (VO₂max) of 53.2 ± 8.3 mL/kg/min. In response to the marathon, global left ventricular and right ventricular ejection fraction decreased in half of the runners; these runners had poorer peak training distance, training time, and fitness level. Change in global left ventricular ejection fraction was associated with VO₂max. Overall, 36% of segments developed edema, 53% decreased function, and 59% decreased perfusion. Significant agreement was observed between segment decreasing function, decreasing perfusion, and developing edema. Myocardial changes were reversible at 3 months.

Conclusions

Completing a marathon leads to localized myocardial edema, diminished perfusion, and decreased function occurring more extensively in less trained and fit runners. Although reversible, these changes might contribute to the transient increase in cardiac risk reported during sustained vigorous exercise.     

Variability in quantitative cardiac magnetic resonance perfusion analysis

By taking advantage of its high spatial resolution, noninvasive and nontoxic nature first-pass perfusion cardiovascular magnetic resonance (CMR) has rendered an indispensable tool for the noninvasive detection of reversible myocardial ischemia. A potential advantage of perfusion CMR is its ability to quantitatively assess perfusion reserve within a myocardial segment, as expressed semi- quantitatively by myocardial perfusion reserve index (MPRI) and fully- quantitatively by absolute myocardial blood flow (MBF). In contrast to the high accuracy and reliability of CMR in evaluating cardiac function and volumes, perfusion CMR is adversely affected by multiple potential reasons during data acquisition as well as post-processing. Various image acquisition techniques, various contrast agents and doses as well as variable blood flow at rest as well as variable reactions to stress all influence the acquired data. Mechanisms underlying the variability in perfusion CMR post processing, as well as their clinical significance, are yet to be fully elucidated. The development of a universal, reproducible, accurate and easily applicable tool in CMR perfusion analysis remains a challenge and will substantially enforce the role of perfusion CMR in improving clinical care.KEY WORDS : Stress cardiac magnetic resonance (CMR) imaging, quantitative analysis, reproducibilityIn the past two decades, first-pass perfusion cardiovascular magnetic resonance (CMR) has rendered an indispensable tool for the noninvasive detection of reversible myocardial ischemia. By taking advantage of its high spatial resolution, noninvasive and nontoxic nature CMR perfusion imaging has achieved an improvement in sensitivity and specificity for the detection of coronary artery disease (CAD) (1) and has given further insights into the understanding of ischemic heart disease.CMR perfusion imaging has been validated against more established invasive, catheter-based (2) as well as other noninvasive imaging modalities [echocardiography (3), single-photon emission computed tomography (SPECT) (4,5), and positron emission tomography (PET)] (6). Ongoing technical innovation with the development of improved hardware, software and novel technical approaches, such as novel spatial-temporal acceleration techniques (7,8), introduction of novel contrast media (9), and blood oxygen-level dependent contrast (10) have improved the exam’s diagnostic performance for the assessment of coronary artery status and myocardial ischemic burden and offered the potential to being employed as a clinical endpoint. In this respect, it is now readily available for routine clinical assessment of CAD patients.A potential advantage of perfusion CMR is its ability to quantify perfusion reserve within a myocardial segment. Although time-demanding, compared to visual interpretation, quantitative evaluation of myocardial perfusion properties with CMR, as expressed semi- quantitatively by myocardial perfusion reserve index (MPRI) (11) and fully- quantitatively by absolute myocardial blood flow (MBF) (12), may provide additional clinically relevant information and an objective, stepwise correlation of myocardial perfusion impairment to the severity of coronary artery status.A semi-quantitative analysis of myocardial perfusion is based on the assessment of the signal-intensity changes over the course of the first pass of the contrast through the myocardium. The upslope integral technique has been the most effective semi- quantitative method that was studied and yields a high diagnostic accuracy in patients with suspected CAD (1). The accuracy of the upslope analysis may, however, be affected by differences in the contrast agent’s pharmacodynamics and pharmacokinetic properties. The use of fully quantitative perfusion analysis helps to avoid these problems. Techniques such as Fermi function deconvolution (13) and dual-bolus contrast administration (14) offer a relatively accurate correlation with myocardial blood flow and yield absolute MBF values, without sacrificing the contrast-to-noise ratio and subsequent image quality.There is limited published data available for the reproducibility of serial myocardial perfusion CMR. Muhling et al. primarily reported good intra- and inter-observer agreement for good quality images, using semi-quantitative analysis in 14 rest and 3 stress adenosine perfusion exams (15). More recently, Morton et al. evaluated the inter-study reproducibility of segmental and global absolute quantitative CMR and the influence of diurnal variation on perfusion, by applying perfusion imaging three times during a single day in eleven healthy volunteers. Inter-study reproducibility was moderate, and best for global rest perfusion. No significant diurnal variation in perfusion was observed (16). In another study aiming in healthy volunteers, Larghat et al. assessed the reproducibility of semi-quantitative and quantitative analysis of first-pass perfusion CMR in healthy volunteers (17). Although they showed good results, reproducibility was affected by variations between intra-observer, inter-observer, and inter-study comparisons. Semi-quantitative analysis was more reproducible than quantitative analysis. Reproducibility of systolic and diastolic phases and the endocardial and epicardial myocardial layer was similar on both semi-quantitative and quantitative analysis. In parallel, as part of Multi-Ethnic Study of Atherosclerosis, the inter-study reproducibility of quantitative CMR perfusion was assessed. Although the interval between the two exams was very long (mean 334 days), interestingly this study also demonstrated reasonable inter-study reproducibility, with global and rest perfusion to be the most reproducible (18).These findings did not differ significantly when perfusion CMR reproducibility had been examined in patients with CAD. Elkington et al. showed good inter-study reproducibility for segmental and global semi-quantitative and quantitative analysis in a cohort of 9 CAD patients and 7 healthy volunteers who underwent adenosine stress perfusion CMR. Reproducibility was good in both patients with and without CAD, and more significant for global versus regional analyses (19). Chih et al. examined the inter-study and inter-observer reproducibility of adenosine stress CMR in patients with symptomatic multi-vessel CAD and low risk for CAD. Myocardial perfusion was evaluated qualitatively by assessing the number of ischemic segments and semi-quantitatively. MPRI was lower in patients with CAD compared to those with low risk. Inter-study and inter-observer reproducibility for MPRI were high. No significant difference in reproducibility was found between patients with CAD and those with low risk CAD (20).In the December 2012 issue of Cardiovascular Diagnosis and Therapy, Goykhman et al. (21) studied retrospectively the inter- and intra-observer reliability of the data generated by standard commercially available software for calculation of the MPRI. Stress CMR was performed using a standardized protocol in 20 women including 10 women with angina and the absence of obstructive CAD and 10 healthy volunteers. Basal, mid, and apical segments, for the whole myocardium, sub-endocardium, and sub-epicardium were analyzed. The MPRI results by repeated software measurements were highly correlated, with potentially important variations in measurement observed. The mid-ventricular level MPRI was most reproducible. Intra-observer measurement was more reproducible than inter-observer measurement.The authors conclude that there is measurement variation inherent in the post processing of the perfusion CMR data using standard commercially available software. This variation is potentially attributed to a combination of factors including variation in stress test response, image acquisition/quality, and variation in measurements at the time of post processing.In contrast to the high accuracy and reliability of CMR in evaluating cardiac function and volumes, perfusion CMR is adversely affected by multiple potential reasons during data acquisition as well as post-processing. Various image acquisition techniques, variation in SA slice acquisitions due to different patient positioning and breath holding, various contrast agents and doses, such as dual bolus administration as well as variable blood flow at rest as well as variable reactions to stress will all influence the acquired data. Postprocessing requires motion compensation, the detection of endo- and epicardial contours, the determination of an input function, as well as deconvolution of the myocardial response, all of which will reduce reproducibility of perfusion imaging (not only with CMR). Reproducibility may also differ due to inherent pitfalls, such as differences in the expertise between centers.Mechanisms underlying the variability in perfusion CMR post processing, as well as their clinical significance, are yet to be fully elucidated. Nonetheless, post- processing variation reflects the practical challenges encountered in both clinical practice and research. No quantitative perfusion analysis technique has been adopted in clinical practice at this time, and visual inspection performed by an experienced reporter remains the mainstay of clinical reporting. An approach to standardize interpretation and post-processing on CMR studies is needed. The development of a universal, reproducible, accurate and easily applicable tool in CMR perfusion analysis remains a challenge and will substantially enforce the role of perfusion CMR in improving clinical care.     

Comparative Assessment of 2-Dimensional Echocardiography vs Cardiac Magnetic Resonance Imaging in Measuring Left Ventricular Mass in Patients With and Without End-Stage Renal Disease

Background

While echocardiography (ECHO)-measured left ventricular mass (LVM) predicts adverse cardiovascular events that are common in hemodialysis (HD) recipients, cardiac magnetic resonance imaging (CMR) is now considered the reference standard for determination of LVM. This study aimed to evaluate concordance between LVM measurements across ECHO and CMR among chronic HD recipients and matched controls.

Methods

A single-centre, cross-sectional study of 41 chronic HD patients and 41 matched controls with normal kidney function was performed to compare LVM measurements and left ventricular hypertrophy (LVH) designation by ECHO and CMR.

Results

In both groups, ECHO, compared with CMR, overestimated LVM. Bland-Altman analysis demonstrated wider agreement limits in LVM measurements by ECHO and CMR in the chronic HD group (mean difference, 60.8 g; limits −23 g to 144.6 g) than in the group with normal renal function (mean difference, 51.4 g; limits −10.5 g to 113.3 g). LVH prevalence by ECHO and CMR in the chronic HD group was 37.5% and 22.5%, respectively, while 17.5% and 12.5% had LVH by ECHO and CMR, respectively, in the normal kidney function group. Intermodality agreement in the designation of LVH was modest in the chronic HD patients (κ = 0.42, P = 0.005) but strong (κ = 0.81, P < 0.001) in the patients with preserved kidney function. Agreement was strong in assessing LVH by ECHO and CMR only in those with normal kidney function.

Conclusions

Our results suggest that the limitations of LVM measurement by ECHO may be more pronounced in patients receiving HD, and provide additional support for the use of CMR in research and clinical practice when rigourous assessment of LVM is essential.     

Predictors of response to intramyocardial bone marrow cell treatment in patients with refractory angina and chronic myocardial ischemia

Background

We previously showed that intramyocardial bone marrow cell (BMC) injection in patients with refractory angina and chronic myocardial ischemia improves myocardial perfusion, cardiac function and disease-related complaints. Treatment effect varied between patients, but the predictors of response remain to be identified. Therefore, the aim of the present study was to assess whether patient characteristics, procedural data and baseline measurements influence the response to intramyocardial BMC treatment in a large cohort of refractory angina patients.

Methods and results

In 120 patients (64 ± 9 years, 88% men) with refractory angina, 97 ± 13 × 10⁶ BMCs were injected intramyocardially in regions with stress-inducible ischemia as assessed by single photon emission computed tomography (SPECT). Canadian Cardiovascular Society angina (CCS) class, quality-of-life score, exercise testing, SPECT and magnetic resonance imaging were performed at baseline and at 3 months follow-up demonstrating significant improvements in CCS class, quality-of-life, exercise capacity, myocardial perfusion and left ventricular function (all variables P < 0.001). Multivariate analysis was performed to evaluate the influence of patient characteristics, procedural data and baseline measurements on BMC treatment response. Based on the improvement of myocardial perfusion at stress, diabetes and a large number of ischemic segments at baseline were shown to be independently associated with a large response to BMC therapy.

Conclusion

The present study demonstrates that diabetes and a large number of ischemic segments are predictors of a large response to intramyocardial BMC injection in refractory angina and chronic ischemia. Furthermore, the safety and efficacy results of previous trials are now confirmed in a larger study population.