The additive prognostic value of perfusion and functional data assessed by quantitative gated SPECT in women

Background  The aim of this study was to assess the prognostic value of technetium-99m tetrofosmin gated SPECT imaging in women using quantitative gated single photon emission computed tomography (SPECT) imaging. Methods  We followed 453 consecutive female patients. Average follow-up was 1.33 years (max. 2.55). Hard endpoints were cardiac death, acute myocardial infarction, or documented ventricular fibrillation. Event-free survival curves were obtained. Optimal cutoff values for left ventricular (LV) volumes, LV ejection fraction (LVEF), and perfusion data to predict outcome were determined by ROC curve analysis. Results  A total of 236 patients had an abnormal study, of whom 27 patients experienced hard events (16 deaths) and 47 patients soft events. For hard events summed stress score (SSS) and LVEF, and for any cardiac event SSS showed independent incremental prognostic value. The survival curves were maximally separated when using cutoff values for SSS of ≥22 and LVEF < 52% (P < 0.001, HR 4.61 and P < 0.001 HR 5.24 for SSS and LVEF resp.), and SSS ≥ 14 (P < 0.001 HR 3.76) for any cardiac event. Conclusion  In women, perfusion and functional parameters derived from quantitative gated technetium-99m tetrofosmin SPECT imaging can adequately be used for cardiac risk assessment. Using quantitative gated SPECT, female patients with an LVEF < 52% or an SSS ≥ 22 are at increased risk for subsequent hard events. Furthermore, patients with an SSS ≥ 14 are at increased risk for any cardiac events.     

Incremental prognostic value of <Superscript>99m</Superscript>Tc-tetrofosmin myocardial SPECT after percutaneous coronary intervention

Objective  Percutaneous transluminal coronary angioplasty is a well-established therapeutic method in selected patients with coronary artery disease. The aim of this study was to assess the incremental prognostic value of technetium-99m (^99mTc)-tetrofosmin myocardial gated-single- photon emission computed tomography (SPECT) in asymptomatic patients after coronary artery stenting. Methods  A total of 246 consecutive patients (aged 55.5 ± 8.2 years, 182 men) participated in the study with a median follow-up of 9.5 years (interquartile ra 5.8–10.5 years). All patients underwent exercise gated-SPECT myocardial imaging within 5–7 months. Myocardial scintigrams were performed using 99mTctetrofosmin, and were evaluated calculating the summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) indexes. Cardiovascular death and non-fatal myocardial infarction were considered as hard cardiac events, and late revascularization (>3 months after myocardial SPECT) procedures as soft events. Receiver-operating characteristic (ROC) analysis was used to test the prognostic ability of SSS and SDS for cardiac events. Cox proportional hazards models were used to evaluate the incremental value of SPECT variables. Results  Cardiac death occurred in 12 (4.9%) patients and non-fatal myocardial infarction in 20 (8.1%) patients. In addition, 60 (24.4%) patients underwent a late revascularization procedure. Using ROC analysis the optimal cut-offs of SSS (AUC = 0.94; 95% CI 0.92–0.97) and SDS (AUC = 0. 76; 95% CI 0.70–0.82) for the prediction of cardiac events were 10 and 1.7, respectively. Multiple Cox regression analyses revealed that SSS > 10 (HR = 24.2; 95% CI 7.44–78.79) and SDS > 1.7 (HR = 2.72; 95% CI 1.23–6.00) provided incremental prognostic value over clinical and exercise test data for the composite end points of any cardiac event. Conclusions   ^99mTc-tetrofosmin myocardial gated- SPECT, performed 6 months post-percutaneous coronary intervention (PCI), provides incremental prognostic information for the prediction of cardiac events in asymptomatic patients after PCI.     

Vascular dysfunction measured by fingertip thermal monitoring is associated with the extent of myocardial perfusion defect

Background  Previous studies have shown that vascular dysfunction measured by digital thermal monitoring (DTM) during an arm-cuff reactive hyperemia procedure correlates with the severity of coronary artery disease measured by coronary artery calcium in asymptomatic patients. Current study investigates the correlation between DTM and abnormal myocardial perfusion imaging (MPI). Methods  About 116 consecutive patients with chest discomfort, age 57 ± 10 years, underwent MPI, DTM and Framingham Risk Score (FRS) assessment. Fingertip temperature rebound (TR), DTM index of vascular reactivity, was assessed after a 2-minute arm-cuff reactive hyperemia test. The extent of myocardial perfusion defect was measured by summed stress score (SSS). Results  TR decreased from SSS < 4 (1.61 ± 0.15) to 4 ≤ SSS ≤ 8 (0.5 ± 0.22) to 9 ≤ SSS ≤ 13 (0.26 ± 0.15) to SSS > 13 (−0.37 ± 0.19) (P = .0001). After adjusting for cardiac risk factors, the odds ratio of the lowest versus two upper tertiles of TR was 3.93 for SSS ≥ 4 and 9.65 for SSS ≥ 8 compared to SSS < 4. TR correlated well with SSS (r = −0.88, P = .0001). Addition of TR to FRS increased the area under the ROC curve to predict abnormal MPI, SSS ≥ 4, from 0.65 to 0.84 (P < .05). Conclusion  Vascular dysfunction measured by DTM is associated with the extent of myocardial perfusion defect independent of age, gender, and cardiac risk factors. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Prediction of 14-year cardiovascular outcomes by dobutamine stress <Superscript>99m</Superscript>Tc-tetrofosmin myocardial perfusion SPECT in elderly patients unable to perform exercise testing

Background

Dobutamine stress myocardial perfusion imaging (MPI) is a useful alternative for the evaluation of coronary artery disease (CAD) in elderly patients who are unable to perform an exercise stress test. However, data on the long-term prognostic value of stress MPI in elderly patients are lacking. Therefore, this study evaluated the long-term prognostic value of dobutamine stress MPI in elderly patients unable to perform an exercise test.

Methods

The study population consisted of 247 elderly patients (mean age 71 ± 5 years) who underwent dobutamine stress single-photon emission computed tomography (SPECT) MPI. An abnormal SPECT study was defined as the presence of fixed and/or reversible perfusion defects. A summed stress score (SSS) was obtained to estimate the extent and severity of perfusion defects. End points during follow-up were all-cause mortality, cardiac mortality, and nonfatal myocardial infarction (MI).

Results

During a median follow-up of 14 years (range 12-16), 168 (68%) patients died (all-cause mortality), of which 56 (23%) were due to cardiac causes. Nonfatal MI occurred in 19 (8%) patients. Kaplan-Meier survival curves showed that MPI provided optimal risk stratification in patients with normal and abnormal MPI. Multivariable analysis identified an abnormal MPI as a strong significant predictor of all-cause mortality and cardiac events. A multivariable analysis also revealed that a reversible defect and SSS were strong long-term predictors of cardiac mortality and hard cardiac events.

Conclusion

Dobutamine stress ^99mTc-tetrofosmin SPECT provides incremental prognostic information for the prediction of long-term cardiovascular outcomes in elderly patients, unable to perform exercise testing. Dobutamine stress MPI is useful in risk classifying elderly patients.

     

Risk stratification among diabetic patients undergoing stress myocardial perfusion imaging

Background

Previous studies have suggested that diabetic patients undergoing single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) are at greater risk for cardiac events than non-diabetic patients with both normal and abnormal imaging results. However, the impact of stress modality on outcomes in this patient group has not been examined.

Methods

The data on all patients undergoing exercise stress or vasodilator stress SPECT MPI from 1996 to 2005 were reviewed. After excluding patients based on our predefined criteria, we subcategorized the study population into diabetic patients and non-diabetic patients. Among the diabetic patients, we identified patients with known coronary artery disease (CAD) and no known CAD. All studies were interpreted using the 17-segment ASNC model. The presence, extent, and severity of perfusion defects were calculated using the summed stress score (SSS), and patients were classified into normal (SSS < 4), mildly abnormal (SSS 4-8), and moderate-severely abnormal (SSS > 8) categories. The annualized cardiac event rate including cardiac death and non-fatal myocardial infarction was calculated over a mean follow-up period of 2.4 ± 1.4 years with a maximum of 6 years.

Results

The cardiac event rate was statistically significantly lower in diabetic patients undergoing exercise stress MPI when compared to the diabetic patients undergoing pharmacological stress MPI across all three perfusion categories (1.3% vs 3.4%, 2.3% vs 5.7%, 4.2% vs 10.7%, respectively). Diabetic patients with no known CAD, who underwent exercise stress MPI had significantly lower cardiac events across all three perfusion categories as compared to the remainder of the diabetic population. Ability to perform exercise stress test was the strongest multivariate predictor of favorable outcome, whereas ejection fraction < 50%, abnormal perfusion imaging on SPECT MPI, and increasing age stood out as independent predictors of adverse outcome in the diabetic patients. Within the abnormal perfusion category, the annualized cardiac event rate among patients undergoing exercise stress SPECT MPI was not statistically different between the diabetic and non-diabetic cohorts.

Conclusion

Diabetic patients undergoing exercise SPECT MPI have a significantly better prognosis than those undergoing pharmacological stress, more similar to patients without diabetes. In patients with diabetes exercise stress test MPI identifies low risk patients and provides precise risk stratification.     

Myocardial perfusion imaging for predicting cardiac events in Japanese patients with advanced chronic kidney disease: 1-year interim report of the J-ACCESS 3 investigation

Purpose

Whether myocardial perfusion imaging (MPI) can predict cardiac events in patients with advanced conservative chronic kidney disease (CKD) remains unclear.

Methods

The present multicenter prospective cohort study aimed to clarify the ability of MPI to predict cardiac events in 529 patients with CKD and estimated glomerular filtration rates (eGFR)?<?50 ml/min per 1.73² without a definitive diagnosis of coronary artery disease. All patients were assessed by stress-rest MPI with ^99mTc-tetrofosmin and analyzed using summed defect scores and QGS software. Cardiac events were analyzed 1 year after registration.

Results

Myocardial perfusion abnormalities defined as summed stress score (SSS) ≥4 and ≥8 were identified in 19 and 7 % of patients, respectively. At the end of the 1-year follow-up, 33 (6.2 %) cardiac events had occurred that included cardiac death, sudden death, nonfatal myocardial infarction, and hospitalization due to heart failure. The event-free rates at that time were 0.95, 0.90, and 0.81 for groups with SSS 0–3, 4–7, and ≥8, respectively (p?=?0.0009). Thus, patients with abnormal SSS had a higher incidence of cardiac events. Multivariate Cox regression analysis showed that SSS significantly impacts the prediction of cardiac events independently of eGFR and left ventricular ejection fraction.

Conclusion

MPI would be useful to stratify patients with advanced conservative CKD who are at high risk of cardiac events without adversely affecting damaged kidneys.     

Incremental prognostic value of dobutamine–atropine stress 99mTc-tetrofosmin myocardial perfusion imaging for predicting outcome in diabetic patients with limited exercise capacity

Purpose This study assessed the incremental value of dobutamine stress ^99mTc-tetrofosmin single-photon emission computed tomography (SPECT) for the prediction of cardiac events in diabetic patients with limited exercise capacity.Methods The study population comprised 125 consecutive diabetic patients (mean age 61±9 years, 61% men) who were unable to perform an exercise test and underwent dobutamine ^99mTc-tetrofosmin SPECT. Follow-up was successful in 124 (99%) patients. Three patients who underwent early revascularisation (within 60 days) were excluded. End-points during follow-up were cardiac death and non-fatal myocardial infarction.Results An abnormal scan (with the presence of reversible or fixed perfusion defects) was observed in 76 (63%) patients. During the follow-up (3.4±1.5 years), 36 patients died (19 cardiac deaths) and four patients had non-fatal myocardial infarction. Cardiac death occurred in one of 49 (2%) patients with a normal myocardial perfusion study and in 18 of 75 (24%) patients with an abnormal study (p<0.001). Abnormal scan was incremental to the clinical parameters in predicting cardiac death (²=48 vs 39, p<0.05) and hard cardiac events (²=50 vs 43, p<0.05).Conclusion Dobutamine stress ^99mTc-tetrofosmin SPECT provides prognostic information additional to clinical data for the prediction of cardiac death and hard cardiac events in diabetic patients unable to perform an exercise test.     

Prognostic significance of stress myocardial gated SPECT among Japanese patients referred for coronary angiography: A study of data from the J-ACCESS database

Purpose  The J-ACCESS [Japanese investigation of prognosis based on gated single photon emission computed tomography (SPECT)] study found that quantitative gated myocardial SPECT (QGS) is valuable for predicting the prognosis of Japanese patients with known or suspected ischaemic heart disease. The present study evaluates the incremental prognostic value of myocardial perfusion imaging (MPI) with QGS among patients referred for coronary angiography (CAG). Methods  Among 4,031 Japanese patients registered at 117 hospitals for the J-ACCESS study, we selected 1,011 who underwent CAG within 3 months before or after MPI with QGS. Summed stress, rest and difference scores (SSS, SRS and SDS) were generated from myocardial perfusion images using a 20-segment scoring system. Myocardial ischaemia was judged visually. End-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) were determined by QGS. Numbers of diseased (> 75% stenosis) coronary vessels (CDV) were assessed by CAG. All patients were followed up for 3 years to determine cardiac events (CE) including cardiac death, non-fatal myocardial infarction and severe heart failure. Univariate and multivariate analyses of prognostic ability included age, cardiac risk factors (hypertension, hyperlipidaemia, diabetes mellitus and prior myocardial infarction), angiographic findings and the QGS parameters as independent variables. Results  Cardiac events occurred more frequently with increasing numbers of coronary vessel lesions (p = 0.0016). Cox univariate analysis revealed that diabetes, CDV, SSS, SDS, EDV, ESV and EF were significant predictors (Wald χ² = 5.99, 12.9, 8.39, 9.11, 35.5, 42.1 and 31.1, respectively), whereas multivariate analysis selected only ESV and SDS as significant predictors (Wald χ² =  36.4, 8.4; p = 0.0038, p < 0.001). Conclusion  MPI with QGS, especially with gated functional data, has incremental prognostic value in addition to angiographic findings. MPI with QGS findings predominantly contribute to the prediction of prognosis rather than numbers of diseased vessels assessed by CAG. Thus, MPI with QGS is the most useful tool with which to guide decisions regarding therapy even among patients referred for CAG.     

Long-term prognostic value of exercise technetium-99m tetrofosmin myocardial perfusion single-photon emission computed tomography

Background

Exercise ^99mTc-tetrofosmin single-photon emission computed tomography (SPECT) is a useful tool for short- and medium-term risk stratifications. Currently, the long-term prognostic application of this technique has not been evaluated.

Methods and Results

Exercise ^99mTc-tetrofosmin was performed in 655 consecutive patients. Ten patients who underwent revascularization <60?days after nuclear testing were excluded from the analysis. The present data are based on 638 patients with complete follow-up. An abnormal SPECT study was defined as the presence of fixed and/or reversible perfusion defects. End points were cardiac death, nonfatal infarction, and late coronary revascularization. A total of 344 (54%) patients had an abnormal SPECT study. Perfusion defects included fixed defects alone in 186 patients (29%) and reversible defects in 158 (25%) patients. During a mean follow-up of 11.0?±?3.3?years, 174 (27%) patients died (all-cause mortality). Nonfatal myocardial infarction occurred in 76 (12%) patients, and late coronary revascularization was performed in 194 (30%) patients. Univariable and multivariable Cox proportional hazard regression analyses showed that exercise ^99mTc-tetrofosmin SPECT provided prognostic information incremental to clinical data and exercise test data. Patients with a normal SPECT had a relatively favorable long-term prognosis, in contrast to patients with an abnormal study who had a significantly increased risk of cardiac events. The SPECT parameters abnormal scan, reversible defect, and summed rest score were strong predictors of long-term outcome.

Conclusion

Exercise ^99mTc-tetrofosmin myocardial perfusion SPECT has an incremental long-term prognostic value over clinical and stress test parameters for the prediction of major adverse cardiac events.     

Diagnostic impact of SPECT image display on assessment of obstructive coronary artery disease

Background  Diagnostic assessment of myocardial perfusion impacts the management of patients with suspected coronary artery disease (CAD). Although various image displays are available for single photon emission computed tomography (SPECT) interpretation, the effects of display differences on SPECT interpretation remain undetermined. Methods and Results  We studied 183 patients undergoing SPECT, including 131 consecutive patients referred for angiography and 52 at low CAD risk. Studies were visually interpreted by use of color and gray images, with readers blinded to the results of the other display. In accordance with established criteria, a summed stress score (SSS) of 4 or greater was considered abnormal. The prevalence of abnormal SPECT findings was higher with gray images than with color images (54% vs 48%, P<.001) based on a uniform criterion (SSS≥4). However, color images yielded equivalent sensitivity (79% vs 82%, P=.7) and improved specificity for global (50% vs 33%, P=.02) and vessel-specific CAD involving the right coronary artery (P<.01) and left anterior descending artery (P<.05). When the criterion for gray images was adjusted upward (SSS≥5) to reflect increased mean defect severity (SSS of 5.1 vs 4.4, P=.01), gray and color images provided equivalent sensitivity and specificity for global and vessel-specific CAD. Conclusions  SPECT interpretation can vary according to image display as a result of differences in perfusion defect severity. Adjustment of abnormality criteria for gray images to reflect minor increases in defect severity provides equivalent diagnostic performance of gray and color displays for CAD assessment. Dr Weinsaft was the recipient of a Doris Duke Clinical Scientist Development Award from the Doris Duke Charitable Foundation (New York, NY)     

123I-mIBG Scintigraphy to predict risk for adverse cardiac outcomes in heart failure patients: Design of two prospective multicenter international trials

Background  ADMIRE-HF (AdreView Myocardial Imaging for Risk Evaluation in Heart Failure) consists of two identical prospective open-label, multicenter, phase 3 studies (MBG311 and MBG312) evaluating the prognostic usefulness of ¹²³I-mIBG scintigraphy for identifying subjects with heart failure who will experience a major adverse cardiac event. Methods  Subjects with NYHA class II and III heart failure and left ventricular ejection fraction ≤35% were eligible for the trials. Subjects underwent planar and SPECT ¹²³I-mIBG myocardial imaging, as well as echocardiography and gated SPECT ^99mTc-tetrofosmin myocardial perfusion imaging. Subjects are then monitored on a regular basis for 2 years. Time to first occurrence of one of the following—NYHA class progression; potentially life-threatening arrhythmic event (including ICD discharge); or cardiac death, as verified by an independent adjudication panel—will be analyzed in comparison to quantitative parameters derived from ¹²³I-mIBG imaging. The primary efficacy analysis will employ the heart/mediastinum ratio on 4-hour delayed planar imaging, while secondary efficacy analyses will examine quantitative results from both planar and SPECT ¹²³I-mIBG images, as well as from ^99mTc-tetrofosmin SPECT and echocardiography. Conclusion  The results of the ADMIRE-HF trials will provide prospective validation of the potential role of ¹²³I-mIBG scintigraphy in assessing prognosis and developing management strategies for patients with heart failure. Funding Source: GE Healthcare.     

Prognostic value of spect myocardial perfusion imaging in patients with elevated cardiac troponin i levels and atypical clinical presentation

Background  We determined the prognostic value of myocardial perfusion imaging (MPI) in patients with atypical clinical presentations and unexpected elevation of cardiac troponin I (cTnI) levels. Methods and Results  In 156 consecutive patients with atypical presentations for acute coronary syndromes (ACS) and elevated cTnI levels undergoing MPI within 30 days, rates of all-cause mortality (100% follow-up; median follow-up, 611 days) and 6-month cardiac death and nonfatal myocardial infarction (96% follow-up; median follow-up, 167 days) were determined. The mean age of the patients was 68 ± 14 years. The majority of the study cohort (96%) was at low to intermediate clinical risk for ACS (Thrombolysis in Myocardial Infarction score for unstable angina/non-ST-segment elevation myocardial infarction < 5). The overall event rate was high, with 45 deaths (28.8%). There were 13 cardiac deaths/nonfatal myocardial infarctions in 6 months (8.3%). A normal MPI result was associated with a high event-free survival rate, whereas an abnormal MPI result was associated with a 3-fold and 7-fold higher risk of all-cause mortality and 6-month cardiac events, respectively. An abnormal MPI result was an independent predictor of all-cause death. Conclusions  In patients with cTnI elevation and a low to intermediate risk for ACS, a normal MPI result portends a good prognosis. Patients with abnormal MPI results have a higher 6-month cardiac event rate and a worse survival rate.     

Long-term prognostic value of exercise <Superscript>99m</Superscript>Tc-MIBI SPET myocardial perfusion imaging in patients after percutaneous coronary intervention

The purpose of this study was to evaluate the long-term prognostic value of exercise technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI) single-photon emission tomography (SPET) imaging in patients after percutaneous coronary intervention (PCI). Three hundred and eighteen consecutive post-PCI patients who underwent exercise and rest ^99mTc-MIBI SPET myocardial perfusion imaging (MPI) were followed up for 38±27 months. Patients with early revascularisation (<3 months after MPI) were excluded. A semiquantitative visual analysis employing a 20-segment and four-point scoring system was used to define the summed stress score (SSS), summed rest score (SRS) and summed difference score (SDS). Death and non-fatal myocardial infarction (MI) were considered as hard events, and late revascularisation procedures (3 months after MPI) as soft events. Fifty-one patients (16.0%) suffered from cardiac events during follow-up, including 1 (0.3%) death, 13 (4.1%) non-fatal MIs, 9 (2.8%) coronary artery bypass grafting procedures and 28 (8.8%) PCIs. According to the SPET results, patients were classified into three groups: patients with normal MPI (SSS=0, n=153), patients with irreversible defects (SDS<3 and SRS>1, n=100) and patients with reversible defects (SDS3, n=65). The annual hard cardiac event rate in patients with reversible defects was 3.9%, which was significantly higher than that in patients with normal MPI (0.2%, ²=7.71; P<0.01). The annual soft cardiac event rate in patients with reversible defects was 10.7%, which was significantly higher than that in patients with irreversible defects (2.5% ²=17.69; P<0.001), and also significantly higher than that in patients with normal MPI (1.5%, ²=33.89; P<0.001). In patients with normal and reversible defects, there was no significant difference in soft and hard cardiac event rates according to whether patients were symptomatic or asymptomatic (P>0.05). However, the annual soft event rate in patients with irreversible defects and symptoms was 5.0%, which was higher than that of 0.6% in asymptomatic patients (²=6.11, P<0.05). Multivariate Cox analysis showed that SSS was the best independent predictor for hard cardiac events (²=12.70; P<0.001) and SDS was the strongest independent predictor for soft cardiac events (²=11.72; P<0.001). Post-PCI patients who have normal exercise ^99mTc-MIBI SPET MPI have a good long-term prognosis, while those with reversible defects are at a higher risk for future cardiac events, without correlation to the chest pain symptoms. However, symptomatic patients with irreversible defects have a higher risk for repeat revascularisation, but not for hard events, compared with asymptomatic patients. Exercise ^99mTc-MIBI SPET MPI has important clinical value for risk stratification and management decision-making in post-PCI patients.     

Stress single photon emission computed tomography for detection of coronary artery disease and risk stratification of asymptomatic patients at moderate risk

Background  The American College of Cardiology Foundation/American Society of Nuclear Cardiology appropriateness criteria document assigns single photon emission computed tomography myocardial perfusion imaging (SPECT MPI) a rating of uncertain for detection and risk assessment of coronary artery disease (CAD) in asymptomatic patients at moderate risk. Methods and Results  The nuclear cardiology database was used to identify 260 asymptomatic patients (67 ± 8 years, 72% men) without known CAD who were at moderate CAD risk according to the Framingham risk score. SPECT MPI images were categorized using the summed stress score (SSS). Mean follow-up 9.9 ± 3.0 years. Abnormal SPECT MPI scans were present in 142 patients (55%). By SSS categories, SPECT scans were low-risk in 67%, intermediate-risk in 20%, and high-risk in 13% of patients. Overall survival at 10 years was 79%, significantly better than the age- and gender-matched Minnesota general population (P < 0.001). Survival was 60% for patients with high-risk scans (95% CI 45-80%), 79% with intermediate-risk scans (95% CI 69-91%), and 83% with low-risk scans (95% CI 77-88%) (P = 0.03), including 84% (95% CI 77-91%) with normal scans. Conclusions  In this retrospectively identified group of asymptomatic patients at moderate CAD risk, stress SPECT MPI was effective for the detection and risk stratification of CAD. Average annual mortality was 4.0% in patients with high-risk scans vs 1.6% in patients with normal scans.     

Resting radionuclide myocardial perfusion imaging in a chest pain center including an overnight delayed image acquisition protocol

Emergency department (ED) patients with chest pain (CP) and a nondiagnostic electrocardiogram (ECG) present difficult management decisions. The purpose of this study was to investigate the utility of resting radionuclide SPECT myocardial perfusion imaging (SPECT MPI)-including an overnight delayed image acquisition protocol-in identifying patients presenting to the ED with CP at risk for cardiac events. METHODS: Patients presenting to the ED with CP and a nondiagnostic ECG were prospectively enrolled and underwent chest pain center evaluation. All patients also underwent resting gated SPECT MPI using (99m)Tc-tetrofosmin tracer. Patients presenting on weeknights between 12 am and 6 am had tracer injection in the ED with image acquisition delayed until later in the morning. Patients were monitored for a 30-d occurrence of cardiac events. RESULTS: Over a 16-mo period, 479 patients were enrolled and completed follow-up. For the prediction of 30-d cardiac events, resting SPECT MPI demonstrated a sensitivity and a specificity of 76.9% and 92.4%, respectively. Positive and negative predictive values were 22.2% and 99.3%, respectively. Among the 3 patients with a normal perfusion scan who suffered cardiac events, all had tracer injection several hours after resolution of CP. The overnight delayed image acquisition protocol provided a negative predictive value of 100% for the 44 patients whose image acquisition was delayed until the following morning. CONCLUSION: A normal resting SPECT MPI in ED patients presenting with CP predicts a very low occurrence of 30-d cardiac events. A delayed image acquisition protocol did not decrease the accuracy of SPECT MPI. Such a protocol may be useful in increasing the availability of this imaging modality.     

Dobutamine myocardial scintigraphy for the prediction of cardiac events after heart transplantation

BACKGROUND: The long-term outcome after heart transplantation (HTx) is essentially influenced by the occurrence and extent of cardiac allograft vasculopathy (CAV). Single photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) has been shown to be a useful and cost-effective non-invasive method in patients with known or suspected coronary artery disease, but its role in detecting CAV remains unclear. AIM: To evaluate the accuracy and predictive value of dobutamine MPI in patients after HTx during a 12-month follow-up. METHODS: Seventy-seven patients (60 males, 17 females) underwent a total of 216 dobutamine MPI examinations over a period of 5 years. Examinations were obtained an average of 89+/-42 months after orthotopic HTx according to a 1-day protocol using 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) with and without attenuation correction. For the present study, findings from 77 MPI examinations (one MPI examination per patient) were analysed visually and semiquantitatively using a 20-segment model. Summed stress scores (SSS) and summed rest scores (SRS) were calculated and receiver operating characteristic (ROC) analysis was performed to detect optimum threshold values. Patients were followed up for 12 months and cardiac events were registered. RESULTS: Cardiac events were observed in 10 of the 77 patients. Good interobserver agreement was found for global visual and SRS-/SSS-based analysis (kappa=0.74 and 0.66, respectively). SSS was superior to SRS in the detection of cardiac events. ROC analysis showed an optimized SSS threshold value of three. For predicting a cardiac event during the 12-month follow-up, global visual and semiquantitative analysis reached sensitivities of 90% and 90%, specificities of 72% and 88%, accuracies of 74% and 87%, positive predictive values of 32% and 53% and negative predictive values of 98% and 98%, respectively. The sensitivity, specificity, accuracy and positive and negative predictive values for MPI to detect clinically relevant coronary artery stenoses (> or =50%) at conventional coronary angiography were 83%, 87%, 86%, 56% and 96%, respectively. CONCLUSIONS: Non-invasive dobutamine MPI reliably identifies patients at risk for subsequent cardiac events in cases of CAV, with a high negative predictive value of 98% and an accuracy of 87%.     

Risk stratification with attenuation corrected stress Tc-99m sestamibi SPECT myocardial perfusion imaging in the absence of ECG-gating due to arrhythmias

Background  Despite growing recognition of attenuation correction (AC) utilizing an external radiation source, prognostic studies using AC are lacking. Methods  Consecutive patients (n = 419) who underwent stress Tc-99m sestamibi SPECT imaging with AC but without ECG-gating, due to arrhythmia, were followed for cardiac death or non-fatal myocardial infarction (MI). A 17-segment model and the summed stress score (SSS) were used to classify both the non-AC and AC images. Results  The 419 patients had a mean age of 71.5 ± 11.7 years and most (70.6%) underwent pharmacologic stress. In follow-up, 35 (8.4%) patients suffered an adverse cardiac event. Patients with AC-SSS 1-3 and AC-SSS 4-8 had similar cardiac event rates (11.4% vs 10.5%, P = NS). Accordingly, AC-SSS cutoffs of 0, 1-8, and >8 were selected to classify perfusion as normal, mildly abnormal, and moderately to severely abnormal with annualized event rates of 2.1%, 10.8%, and 18.7%, respectively (P < .001). In multivariable analysis, AC-SSS >8 was the most powerful predictor of cardiac events followed by AC-SSS 1-8, history of CAD, age >75 and pharmacologic stress. Conclusions  AC provides powerful risk stratification when added to clinical variables in patients undergoing stress Tc-99m sestamibi SPECT imaging without ECG-gating. Moreover, smaller/less severe defects on AC data are more significant than if the same defects were seen on non-AC data.     

Prognostic value of myocardium perfusion imaging with a new reconstruction algorithm

Background

It has been demonstrated that a new reconstruction algorithm for myocardium perfusion imaging (MPI) allows faster acquisition with similar accuracy. The prognostic value of MPI performed with this software and short acquisition time is unknown.

Methods

To determine the prognostic value we followed 3184 consecutive MPI patients between March 2008 and March 2010. A 2-day protocol with low dose 99mTc-MIBI (10-12 mCi) and a 6-minute acquisition was used. Exercise stress was used in 62.6 % of the studies. Scans were reconstructed using the software “Evolution for cardiac”. Perfusion defects were quantified by summed stress score (SSS) and categorized in four groups: SSS0 = 0; SSS1 = 1-3; SSS2 = 4-8; and SSS3 ≥ 9. Patients were phone contacted every 6 months for follow up and hard events were defined as death or myocardial infarction (MI) and total events as hard events plus late revascularization.

Results

The mean radiation dose was <7 mSv/patient. Mean F/U was 33 ± 20 months; 140 of the patients were lost to follow up and 86 were censored due early revascularization (<60 days after MPS). There were 140 hard events: 89 deaths and 51 MI. Mean age was 61.5 ± 12.3 years and 57.7 % were male. Hard event rate was 0.8 %/year in patients with normal MPS and 3.7 %/year in those with abnormal MPS. Patients with larger defects had nine times more hard events than patients with SSS = 0 (14.2 % vs 1.6 %). Revascularization was more frequent in patients with abnormal MPS than normal MPS (21.7 % vs 3.9 %; P < 0.001). Cox proportional hazard analysis showed that SSS was an independent predictor of hard events and revascularization.

Conclusions

The use of reduced-dose, fast myocardial perfusion SPECT and the new processing algorithm lowers acquisition time and radiation exposure compared to conventional SPECT without compromising the well-established prognostic value of MPI.     

Comparison of dobutamine stress echocardiography, dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging in patients with end-stage renal disease

Objectives  We sought to assess and compare the diagnostic accuracy and prognostic value of dobutamine stress echocardiography (DSE), dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging (MPI) in patients with end-stage renal disease (ESRD). Background  The optimal stress imaging modality for patients with ESRD has not yet been determined. Methods  Forty-nine patients with ESRD underwent DSE, dobutamine SPECT MPI, and adenosine SPECT MPI. The primary endpoint of the trial was concordance between stress tests with respect to the presence or absence of ischemia. Results  Agreement on the presence or absence of ischemia between adenosine SPECT MPI and DSE was 69% (kappa = .25, P = NS). Agreement on the presence or absence of ischemia between adenosine and dobutamine SPECT MPI was 77% (kappa = .37, P = <.009). Summed stress scores for adenosine and dobutamine SPECT MPI studies were highly correlated (r = .9, P = <.0001). DSE and SPECT MPI results provided incremental prognostic information when added to clinical variables. Conclusions  There is moderate concordance between DSE and adenosine SPECT MPI in ESRD patients referred for stress testing. Interobserver agreement was higher for SPECT MPI compared to DSE. Based on these observations, the optimal approach for diagnosing severe coronary artery disease and assessing risk in patients with ESRD has yet to be determined, but appears to warrant further investigation. Supported by grants from Hennepin Faculty Associates, the Minneapolis Medical Research Foundation, and DuPont Pharmaceuticals.     

Risk stratification using line source attenuation correction with rest/stress Tc-99m sestamibi SPECT myocardial perfusion imaging

Background

Although line source attenuation correction (AC) in SPECT MPI studies improves diagnostic accuracy, its prognostic value is less understood.

Methods

Consecutive patients (n = 6,513) who underwent rest/stress AC ECG-gated SPECT MPI were followed for cardiac death or non-fatal myocardial infarction (MI). A 17-segment model and AC summed stress score (SSS) were used to classify images.

Results

Of the 6,513 patients, cardiac death or non-fatal MI occurred in 267 (4.1%), over 2.0 ± 1.4 years. The AC-SSS in patients with a cardiac event (5.6 ± 7.8) was significantly higher than in those without (1.9 ± 4.6, P < .001). The annualized cardiac event rate in patients with an AC-SSS 1-3 (3.6%) was significantly higher than in those with an AC-SSS = 0 (1.1%, P < .001) but similar to that in those with an AC-SSS 4-8 (2.9%, P = .4). Accordingly, patients were classified to AC-SSS = 0, 1-8, and >8 with annualized cardiac event rates of 1.1%, 3.2%, and 8.5%, respectively (P < .0001). In multivariate analysis, an AC-SSS 1-8 and >8 emerged as independent predictors of cardiac events (P < .02 and P < .0001, respectively).

Conclusion

Rest/stress ECG-gated SPECT MPI with line source AC provides highly effective and incremental risk stratification for future cardiac events.