<Emphasis Type="Bold">Discrepancies between coronary CT angiography and invasive coronary angiography with focus on culprit lesions which cause future cardiac events</Emphasis>

Objectives

To evaluate the clinical significance of discrepant lesions between coronary computed tomography angiography (CCTA) and invasive coronary angiography (ICA) in a longitudinal study.

Methods

In 220 patients with suspected coronary artery disease (CAD) who underwent both 256-row CCTA and ICA, the obstructive CAD (≥ 50% stenosis) on CCTA was compared with that on ICA as the reference standard. We analysed the causes of the discrepancy between CCTA and ICA. During a 40-month follow-up period, major adverse cardiac events (MACE) were assessed.

Results

Discordance between CCTA and ICA was observed in 121 of the 3166 coronary artery segments (3.8%). Common causes were calcification (45.9%) and positive remodelling (PR) (29.6%) in 83 false positive lesions, and noise (40.0%) and motion artefact (37.8%) in 38 false negative lesions. MACE occurred in seven lesions among the discrepant lesions; six among the 29 PR lesions (20.7%) and one among the 53 calcified lesions (1.9%). With respect to the prediction power of MACE in an intermediate stenosis, the CCTA-related value including PR was higher than the ICA-related value.

Conclusions

PR was a frequent cause of MACE among the false positive lesions on CCTA. Therefore, the presence of PR on CCTA may suggest clinical significance, although it can be missed by ICA.

Key Points

? Compared to ICA, PR in CCTA may be cause of false positive lesion. ? CCTA-related value including PR shows higher prediction power of MACE than ICA-related value. ? PR reflects atherosclerotic burden that can be related to cardiac events. ? PR in CCTA should be observed carefully, even if it is false positive.

     

Coronary artery calcium score and CT angiography in asymptomatic elderly patients with high pretest probability for coronary artery disease

Purpose

To evaluate the role of coronary artery calcium scoring (CACS) and/or coronary CT angiography (CCTA) in asymptomatic elderly patients with high pretest probability for coronary artery disease (CAD).

Materials and methods

Forty-eight consecutive asymptomatic elderly (>65 years) subjects who had a high pretest probability and underwent CACS/CCTA were included. Each CCTA was evaluated for adequacy for assessment of coronary stenosis. Significant stenosis (>50 % diameter narrowing) was assessed on evaluable CT images and by invasive catheter angiography (ICA).

Results

All subjects were men with mean CACS of 880 ± 1779. Among those with low (0–99), intermediate (100–399), and high (400–999) CACS, ICA-verified significant stenosis was present in 8 % (1/13), 23 % (2/13), and 67 % (8/12), respectively. Among those with very high CACS (≥1000) (n = 10), 90 % of CCTAs were not evaluable for stenosis.

Conclusion

In asymptomatic elderly subjects with high pretest probability, CACS followed by CCTA may be considered for those with intermediate to high CACS.

     

Using coronary CT angiography for guiding invasive coronary angiography: potential role to reduce intraprocedural radiation exposure

Objectives

We investigated the potential reduction of patient exposure during invasive coronary angiography (ICA) if the procedure had only been directed to the vessel with at least one ≥ 50% stenosis as described in the CT report.

Methods

Dose reports of 61 patients referred to ICA because of at least one ≥ 50% stenosis on coronary CT angiography (CCTA) were included. Dose–area product (DAP) was documented separately for left (LCA) and right coronary arteries (RCA) by summing up the single DAP for each angiographic projection. The study population was subdivided as follows: coronary intervention of LCA (group 1) or RCA (group 2) only, or of both vessels (group 3), or further bypass grafting (group 4), or no further intervention (group 5).

Results

57.4% of the study population could have benefitted from reduced exposure if catheterization had been directly guided to the vessel of interest as described on CCTA. Mean relative DAP reductions were as follows: group 1 (n = 18), 11.2%; group 2 (n = 2), 40.3%; group 3 (n = 10), 0%; group 4 (n = 3), 0%; group 5 (n = 28), 28.8%.

Conclusions

Directing ICA to the vessel with stenosis as described on CCTA would reduce intraprocedural patient exposure substantially, especially for patients with single-vessel stenosis.

Key points

? Patients with CAD can benefit from decreased radiation exposure during coronary angiography. ? ICA should be directed solely to significant stenoses as described on CCTA. ? Severely calcified plaques remain a limitation of CCTA leading to unnecessary ICA referrals.

     

Prognostic value of coronary atherosclerosis progression evaluated by coronary CT angiography in patients with stable angina

Objectives

To investigate the progression of coronary atherosclerosis burden by coronary CT angiography (CCTA) and to demonstrate its association with the incidence of major adverse cardiac events (MACE).

Methods

We retrospectively studied patients with stable angina who had undergone repeat CCTA due to recurrent or worsening symptoms. Lipid-rich, fibrous, calcified and total plaque burden as well as coronary diameter stenosis were quantitatively analysed. The incidence of MACE during follow-up was determined.

Results

The final cohort consisted of 268 patients (mean age 52.9 ± 9.8 years, 71 % male) with a mean follow-up period of 4.6 ± 0.9 years. Patients with lipid-rich, fibrous, calcified and total plaque burden (%) progression, as well as coronary diameter stenosis (%) progression had a significantly higher incidence of MACE than those without (all p < 0.05). The progression of lipid-rich plaque (HR = 1.601, p = 0.021), total plaque burden (HR = 2.979, p = 0.043) and coronary diameter stenosis (HR = 4.327, p <0.001) were independent predictors of MACE (all p < 0.05).

Conclusions

Patients presenting with recurrent or worsening symptoms associated with coronary artery disease who have coronary atherosclerosis progression on CCTA are at an increased risk of future MACE.

Key Points

? Repeat CCTA can provide information regarding the progression of coronary atherosclerosis. ? Coronary atherosclerosis progression at CCTA is independently associated with MACE. ? CCTA findings could serve as incremental predictors of MACE.

     

Coronary flow reserve and relative flow reserve measured by N-13 ammonia PET for characterization of coronary artery disease

Objective

We evaluated the relationships between coronary flow reserve (CFR) and relative flow reserve (RFR) measured by N-13 ammonia positron emission tomography (PET) for characterization of epicardial coronary artery disease (CAD).

Methods

Sixty-nine consecutive stable angina patients underwent N-13 ammonia PET, coronary computed tomography angiography (CCTA), and if necessary, invasive coronary angiography (CAG) within 2 weeks. Myocardial blood flow (MBF), CFR, RFR, and coronary vascular resistance of the reference arterial territory (CVR_ref) were measured by N-13 ammonia PET. The presence of significant stenosis (SS) and diffuse atherosclerosis (DA) was evaluated on CCTA and CAG. Functional parameters measured by PET were compared among arteries with and without SS and DA.

Results

Arteries with SS and those with DA showed significantly lower stress MBF, as compared to those without. RFR was significantly lower in arteries with SS as compared to those without, while CFR was not. CFR was significantly lower in arteries with DA as compared to those without, while RFR was not. Among arteries without SS, CFR was significantly lower in those with DA as compared to those without. However, among arteries with SS, CFR was similar between those with and without DA. In contrast, RFR was significantly lower in arteries with SS, regardless of the presence of DA. CFR and RFR showed a weak positive correlation (r = 0.269) with discordance in 24 cases (35%). Among the arteries with CFR-RFR discordance, the prevalence of DA was significantly higher in those with low CFR but preserved RFR, as compared to those with preserved CFR but low RFR (75 vs 25%, p = 0.028). CVR_ref was significantly higher in arteries with DA, implicating a correlation of DA with underlying microvascular disease.

Conclusions

CFR and RFR measured by myocardial perfusion PET could provide a comprehensive information for characterization of epicardial CAD.

     

Negative predictive value of stress myocardial perfusion imaging and coronary computed tomography angiography: A meta-analysis

Background

Comparing the prognostic value of a negative finding by stress single-photon emission computed tomography myocardial perfusion imaging (MPI) and coronary computed tomography angiography (CCTA) may be useful to evaluate how better identify low-risk patients. We performed a meta-analysis to compare the long-term negative predictive value (NPV) of normal stress MPI and normal CCTA in subjects with suspected coronary artery disease (CAD).

Methods and Results

Studies published between January 2000 and November 2016 were identified by database search. We included MPI and CCTA studies that followed-up ≥100 subjects for ≥5 years and providing data on clinical outcome for patients with negative tests. Summary risk estimates for normal perfusion at MPI or <50% coronary stenosis at CCTA were derived in random effect regression analysis, and causes of heterogeneity were determined in meta-regression analysis. We identified 12 eligible articles (6 MPI and 6 CCTA) including 33,129 patients (26,757 in MPI and 6372 in CCTA studies) with suspected CAD. The pooled annualized event rate (AER) for occurrence of hard events (death and nonfatal myocardial infarction) was 1.06 (95% confidence interval, CI 0.49-1.64) in MPI and 0.61 (95% CI 0.35-0.86) in CCTA studies. The pooled NPV was 91% (95% CI 86-96) in MPI and 96 (95% CI 95-98) in CCTA studies. The summary rates between MPI and CCTA were not statistically different. At meta-regression analysis, no significant association between AER and clinical and demographical variables considered was found for overall studies.

Conclusions

Stress MPI and CCTA have a similar ability to identify low-risk patients with suspected CAD.

     

Myocardial segmentation based on coronary anatomy using coronary computed tomography angiography: Development and validation in a pig model

Objectives

To validate a method for performing myocardial segmentation based on coronary anatomy using coronary CT angiography (CCTA).

Methods

Coronary artery-based myocardial segmentation (CAMS) was developed for use with CCTA. To validate and compare this method with the conventional American Heart Association (AHA) classification, a single coronary occlusion model was prepared and validated using six pigs. The unstained occluded coronary territories of the specimens and corresponding arterial territories from CAMS and AHA segmentations were compared using slice-by-slice matching and 100 virtual myocardial columns.

Results

CAMS more precisely predicted ischaemic area than the AHA method, as indicated by 95% versus 76% (p?<?0.001) of the percentage of matched columns (defined as percentage of matched columns of segmentation method divided by number of unstained columns in the specimen). According to the subgroup analyses, CAMS demonstrated a higher percentage of matched columns than the AHA method in the left anterior descending artery (100% vs. 77%; p?<?0.001) and mid- (99% vs. 83%; p?=?0.046) and apical-level territories of the left ventricle (90% vs. 52%; p?=?0.011).

Conclusions

CAMS is a feasible method for identifying the corresponding myocardial territories of the coronary arteries using CCTA.

Key Points

? CAMS is a feasible method for identifying corresponding coronary territory using CTA ? CAMS is more accurate in predicting coronary territory than the AHA method ? The AHA method may underestimate the ischaemic territory of LAD stenosis

     

Long-term prognostic value of stress myocardial perfusion imaging and coronary computed tomography angiography: A meta-analysis

Background

We conducted a meta-analysis to compare the long-term prognostic value of stress single-photon emission computed tomography myocardial perfusion imaging (MPI) and coronary computed tomography angiography (CCTA) for adverse cardiovascular events in subjects with suspected or known coronary artery disease.

Methods and Results

We searched PubMed, Cochrane, Web of Science, and Scopus database between January 2000 and December 2014 for stress MPI and CCTA studies that followed up ≥ 100 subjects for ≥ 2.5 years and provided the unadjusted and/or adjusted hazard ratio (HR) at Cox regression analysis. Summary risk estimates for abnormal perfusion at MPI or ≥ 50% coronary stenosis at CCTA were derived in random effect regression analysis, and causes of heterogeneity were determined in meta-regression analysis. We identified 21 eligible articles (10 MPI and 11 CCTA) including 25,258 participants (13,484 in MPI and 11,774 in CCTA studies) with suspected or known coronary artery disease. Among the included publications, 8 MPI and 8 CCTA studies reported the HR for the occurrence of hard events (death and nonfatal myocardial infarction). The pooled HR was comparable for MPI and CCTA studies. The HR for the occurrence of a combined endpoint including revascularization as event was reported in 4 MPI and 6 CCTA studies. The pooled HR was higher for CCTA compared to MPI (P < .05) also when only MPI and CCTA studies with limited representation of prior CAD were considered.

Conclusions

The long-term prognostic value of MPI and CCTA for the occurrence of hard events is similar. However, the association between event-free survival and CCTA is higher than MPI when coronary revascularization is included in the endpoint.

     

Rationale,design and goals of the HeartFlow assessing diagnostic value of non-invasive FFRCT in Coronary Care (ADVANCE) registry

Background

Coronary CT angiography (CTA) is a reliable tool for the detection of coronary artery disease (CAD) that conveys significant prognostic information. It does not provide data on the hemodynamic significance of a given lesion, particularly in intermediate-grade stenosis. Fractional flow reserve by CT (FFR_CT) can accurately predict the hemodynamic significance of coronary lesions. The primary objective of this registry is to determine whether the integration of FFR_CT as an adjunct to coronary CTA will lead to a significant change in the management of CAD in patients with stable angina.

Segmental quantitative myocardial perfusion with PET for the detection of significant coronary artery disease in patients with stable angina

Purpose

The goal of this study is to determine the technical accuracy of segmental perfusion parameters assessed with quantitative cardiac PET imaging in the evaluation of coronary artery disease (CAD) in patients with stable angina.

Methods

A cohort of patients who participated in the EVINCI protocol underwent an evaluation of coronary anatomy by invasive coronary angiography (ICA) and/or coronary computed tomography angiography (CCTA) and PET myocardial perfusion imaging with H₂ ¹⁵O, ¹³NH₃ or ⁸²Rb. PET studies were analyzed by two independent observers blinded to clinical and instrumental data, and classified as positive or negative for significant CAD using only segmental perfusion measurements and cut-off values from literature.

Results

On a per-patient basis, the overall inter-observer agreement on PET results was 90 % (kappa?=?0.79), indicating substantial agreement. On a per-vessel basis, the inter-observer agreement on PET results was 88 % (kappa?=?0.74) in the RCA territory, 94 % (kappa?=?0.84) in the LAD territory and 94 % (kappa?=?0.85) in the LCX territory.Segmental PET measurements correctly identified 85 % of the patients, resulting in a global sensitivity of 86 %, a specificity of 84 %, a positive predictive value (PPV) of 69 % and a negative predictive value (NPV) of 93 %.In vessel-based analyses, quantitative perfusion parameters had a sensitivity, specificity, PPV and NPV of 92 %, 82 %, 42 % and 99 %, respectively, for the detection of significant coronary stenoses in all major coronary arteries.

Conclusions

The assessment of absolute myocardial perfusion parameters measured at a segment level lead to reliable and accurate identification of patients with significant coronary stenosis at ICA and/or CCTA.

     

Improved diagnostic performance of transluminal attenuation gradient in combination with morphological evaluation of coronary artery stenosis using 320-row computed tomography

Purpose

To assess the utility of transluminal attenuation gradient (TAG) in combination with coronary computed tomography angiography (CTA) for detecting obstructive coronary artery stenosis.

Materials and methods

We retrospectively evaluated coronary CTA data in 35 consecutive patients who underwent invasive coronary angiography (ICA). We compared the diagnostic performance of TAG with that of quantitative coronary angiography, which we used as the reference standard. For the combination of TAG and coronary CTA, we designed a logical conjunction model (CCTA&&TAG) as well as a logical disjunction model (CCTA||TAG), and evaluated their diagnostic accuracies.

Results

Among 130 vessels of 35 patients, 30 lesions (23%) showed significant stenosis on ICA. TAG predicted significant coronary artery stenosis with a sensitivity of 75%, specificity of 63%, positive predictive value of 40%, negative predictive value of 89%, and accuracy of 66%, and had a cutoff value of ? 15.4 HU/10 mm. The respective values for CCTA&&TAG were 73, 98, 88, 90, and 90%; those for CCTA||TAG were 94, 61, 56, 94, and 72%. CCTA&&TAG improved the diagnostic accuracy significantly more than CCTA||TAG.

Conclusion

TAG in conjunction with coronary CTA improves the diagnostic accuracy of coronary CTA.

     

Image quality and radiation dose of coronary CT angiography performed with whole-heart coverage CT scanner with intra-cycle motion correction algorithm in patients with atrial fibrillation

Objectives

To evaluate image quality, coronary evaluability and radiation exposure of coronary CT angiography (CCTA) performed with whole-heart coverage cardiac-CT in patients with atrial fibrillation (AF).

Materials and methods

We prospectively enrolled 164 patients with AF who underwent a clinically indicated CCTA with a 16-cm z-axis coverage scanner. In all patients CCTA was performed using prospective ECG-triggering with targeted RR interval. We evaluated image quality, coronary evaluability and effective dose (ED). Patients were divided in two subgroups based on heart rate (HR) during imaging. Group 1: 64 patients with low HR (<75 bpm), group 2: 100 patients with high HR (≥75 bpm). Written informed consent was obtained from all patients and the institutional ethics committee approved the study protocol.

Results

In a segment-based analysis, coronary evaluability was 98.4 % (2,577/2,620 segments) in the whole population, without significant differences between groups (1,013/1,024 (98.9 %) and 1,565/1,596 (98.1 %), for groups 1 and 2, respectively, p=0.15). Mean ED was similar in both groups (3.8±1.9 mSv and 3.9±2.1 mSv in groups 1 and 2, respectively, p=0.75)

Conclusions

The whole-heart-coverage scanner could evaluate coronary arteries with high image quality and without increase in radiation exposure in AF patients, even in the high HR group.

Key points

? Last-generation CT scanner improves coronary artery assessment in AF patients. ? The new CT scanner enables low radiation exposure in AF patients. ? Diagnostic ICA maybe avoided in AF patients with suspected CAD. ? Whole-heart coverage CT scanner enables low radiation exposure in AF patients.

     

Relationship between diverse patient body size- and image acquisition-related factors,and quantitative and qualitative image quality in coronary computed tomography angiography: a multicenter observational study

Purpose

We investigated the effects of patient- and image acquisition-related factors on the image quality in coronary CT angiography (CCTA).

Materials and methods

We enrolled 1197 patients (728 men; 65 ± 12 years). All underwent CCTA under the routine scan protocol in 23 participating hospitals. The subjective image quality (3-point Likert scale: excellent, good, and poor) and the attenuation of the left and right coronary artery (LCA, RCA) were recorded; the effects of patient and image acquisition-related factors on vascular attenuation were then compared.

Results

The mean LCA attenuation was 515.2 ± 65.8 (excellent), 401.4 ± 63.4 (good), and 319.5 ± 47.6 HU (poor). The corresponding RCA attenuation was 496.6 ± 67.6, 390.5 ± 58.5, and 308.5 ± 50.7 HU, respectively. Univariate analysis revealed significant associations between sufficient coronary attenuation (> 400 HU) and the age, gender, body surface area (BSA), number of detectors, contrast synchronization, scan mode, and the fractional contrast dose. Multivariate analysis revealed that the bolus tracking method, prospective electrocardiogram gating, and fractional contrast dose were significantly associated with sufficient coronary enhancement.

Conclusion

BSA and fractional contrast dose are the most important patient- and image acquisition-related factors for sufficient coronary attenuation in CCTA.

     

Comprehensive morphologic and functional imaging of heart transplant patients: first experience with dynamic perfusion CT

Objectives

We aimed to assess the diagnostic performance of a combined protocol with coronary computed tomography angiography (CCTA) and stress CT perfusion imaging (CTP) in heart transplant patients for comprehensive morphological and functional imaging.

Methods

In this prospective study, 13 patients undergoing routine follow-up 8±6 years after heart transplantation underwent CCTA and dynamic adenosine stress CTP using a third-generation dual-source CT scanner, cardiac magnetic resonance (MR) adenosine stress perfusion imaging at 1.5 T, and catheter coronary angiography. In CCTA stenoses >50% luminal diameter narrowing were noted. Myocardial perfusion deficits were documented in CTP and MR. Quantitative myocardial blood flow (MBF) was calculated with CTP. Left ventricular ejection fraction was determined on cardiac MR cine images. Radiation doses of CT were determined.

Results

One of the 13 patients had to be excluded because of severe motion artifacts. CCTA identified three patients with stenosis >50%, which were confirmed with catheter coronary angiography. CTP showed four patients with stress-induced myocardial hypoperfusion, which were confirmed by MR stress perfusion imaging. Quantitative analysis of global MBF showed lower mean values as compared to known reference values (MBF under stress 125.5 ± 34.5 ml/100 ml/min). Average left ventricular ejection fraction was preserved (56 ± 5%).

Conclusions

In heart transplant patients, a comprehensive CT protocol for the assessment of morphology and function including CCTA and CTP showed good concordance to results from MR perfusion imaging and catheter coronary angiography.

Key Points

? Stress CT perfusion imaging enables the detection of myocardial ischemia ? CT myocardial perfusion imaging can be combined with coronary computed tomography angiography ? Combining perfusion and coronary CT imaging is accurate in heart transplant patients ? CT myocardial perfusion imaging can be performed at a reasonable radiation dose

     

Combined evaluation of regional coronary artery calcium and myocardial perfusion by <Superscript>82</Superscript>Rb PET/CT in the identification of obstructive coronary artery disease

Purpose

Cardiac imaging with PET/CT allows measurement of coronary artery calcium (CAC), myocardial perfusion and coronary vascular function. We investigated whether the combined assessment of regional CAC score, ischemic total perfusion deficit (ITPD) and quantitative coronary vascular function would further improve the diagnostic accuracy of PET/CT in predicting obstructive coronary artery disease (CAD).

Methods

We analyzed 113 patients with suspected CAD referred to ⁸²Rb PET/CT myocardial perfusion imaging with available coronary angiographic data. Obstructive CAD was defined as ≥75% stenosis. The receiver operating characteristic area under curve (AUC) was applied to evaluate the ability of CAC score, ITPD, hyperemic myocardial blood flow (MBF) and coronary flow reserve (CFR) to identify CAD.

Results

Vessels with obstructive CAD (71 vessels) had higher ITPD (4.6?±?6.2 vs. 0.6?±?1.3) and lower hyperemic MBF (1.01?±?0.5 vs. 1.75?±?0.6 ml/min/g) and CFR (1.56?±?0.6 vs. 2.38?±?0.7; all p?<?0.001) than those without. In prediction of per-vessel CAD, the AUCs for the models including CAC/ITPD/hyperemic MBF (0.869) and CAC/ITPD/CFR (0.875) were higher (both p?<?0.01) than for the model including CAC/ITPD (0.790). Compared with CAC/ITPD, continuous net reclassification improvement was 0.69 (95% bootstrap confidence interval, CI, 0.365–1.088) for the CAC/ITPD/hyperemic MBF model and 0.99 (95% bootstrap CI 0.64–1.26) for the CAC/ITPD/CFR model.

Conclusion

Hyperemic MBF and CFR provide incremental information about the presence of CAD over CAC score and perfusion imaging parameters. The combined use of CAC, myocardial perfusion imaging and quantitative coronary vascular function in may help predict more accurately the presence of obstructive CAD.

     

Correlation and predictive value of aortic root calcification markers with coronary artery calcification and obstructive coronary artery disease

Objective

To evaluate the correlation between aortic root calcification (ARC) markers and coronary artery calcification (CAC) derived from coronary artery calcium scoring (CACS) and their ability to predict obstructive coronary artery disease (CAD).

Methods

We retrospectively analyzed 189 patients (47% male, age 60.3 ± 11.1 years) with an intermediate probability of CAD who underwent clinically indicated CACS and coronary CT angiography (CCTA). ARC markers [aortic root calcium score (ARCS) and volume (ARCV)] were calculated and compared to CAC markers: coronary artery calcium score (CACS), volume (CACV), and mass (CACM). CCTA datasets were visually evaluated for significant CAD (stenosis ≥ 50%) and the ability of ARC markers to predict obstructive CAD was assessed.

Results

ARCS (mean 67.7 ± 189.5) and ARCV (mean 67.3 ± 184.7) showed significant differences between patients with and without CAC (109.4 ± 238.6 vs 9.42 ± 31.4, p < 0.0001; 108.5 ± 232.4 vs 9.9 ± 30.5, p < 0.0001). A strong correlation was found for ARCS and ARCV with CACS, CACM, and CACV (all p < 0.0001). In a multivariate analysis, ARCS (OR 1.09, p = 0.033) and ARCV (OR 1.12, p = 0.046) were independent markers for CAC. Using a receiver-operating characteristics analysis, the AUC to detect severe CAC was 0.71 (p < 0.0001) and 0.71 (p < 0.0001) for ARCS and ARCV, respectively. ARCS (0.67, p < 0.0001) and ARCV (0.68, p < 0.0001) showed discriminatory power for predicting obstructive CAD, yielding sensitivities 61 and 78% and specificities of 62 and 80%, respectively.

Conclusion

ARC markers are associated with and independently predict the presence of CAC and obstructive CAD. Further testing is required in patients with severe ARC and significant CAD in order to reliably obtain these markers from thoracic-CT or X-ray for proper risk classification.

     

First validation of myocardial flow reserve assessed by dynamic <Superscript>99m</Superscript>Tc-sestamibi CZT-SPECT camera: head to head comparison with <Superscript>15</Superscript>O-water PET and fractional flow reserve in patients with suspected coronary artery disease. The WATERDAY study

Purpose

We assessed the feasibility of myocardial blood flow (MBF) and flow reserve (MFR) estimation using dynamic SPECT with a novel CZT camera in patients with stable CAD, in comparison with ¹⁵O–water PET and fractional flow reserve (FFR).

Methods

Thirty patients were prospectively included and underwent FFR measurements in the main coronary arteries (LAD, LCx, RCA). A stenosis ≥50% was considered obstructive and a FFR abnormal if ≤0.8. All patients underwent a dynamic rest/stress ^99mTc-sestamibi CZT-SPECT and ¹⁵O–water PET for MBF and MFR calculation. Net retention kinetic modeling was applied to SPECT data to estimate global uptake values, and MBF was derived using Leppo correction. Ischemia by PET and CZT-SPECT was considered present if MFR was lower than 2 and 2.1, respectively.

Results

CZT-SPECT yielded higher stress and rest MBF compared to PET for global and LAD and LCx territories, but not in RCA territory. MFR was similar in global and each vessel territory for both modalities. The sensitivity, specificity, accuracy, positive and negative predictive value of CZT-SPECT were, respectively, 83.3, 95.8, 93.3, 100 and 85.7% for the detection of ischemia and 58.3, 84.6, 81.1, 36.8 and 93% for the detection of hemodynamically significant stenosis (FFR?≤?0.8).

Conclusions

Dynamic ^99mTc-sestamibi CZT-SPECT was technically feasible and provided similar MFR compared to ¹⁵O–water PET and high diagnostic value for detecting impaired MFR and abnormal FFR in patients with stable CAD.

     

Prognostic value of coronary computed tomography angiography in diabetic patients without chest pain syndrome

Aims

Diabetic patients with coronary artery disease (CAD) are often free of chest pain syndrome. A useful modality for non-invasive assessment of CAD is coronary computed tomography angiography (CTA). However, the prognostic value of CAD on coronary CTA in diabetic patients without chest pain syndrome is relatively unknown. Therefore, the aim was to investigate the long-term prognostic value of coronary CTA in a large population diabetic patients without chest pain syndrome.

Methods

Between 2005 and 2013, 525 diabetic patients without chest pain syndrome were prospectively included to undergo coronary artery calcium (CAC)-scoring followed by coronary CTA. During follow-up, the composite endpoint of all-cause mortality, non-fatal myocardial infarction (MI), and late revascularization (>90 days) was registered.

Results

In total, CAC-scoring was performed in 410 patients and coronary CTA in 444 patients (431 interpretable). After median follow-up of 5.0 (IQR 2.7-6.5) years, the composite endpoint occurred in 65 (14%) patients. Coronary CTA demonstrated a high prevalence of CAD (85%), mostly non-obstructive CAD (51%). Furthermore, patients with a normal CTA had an excellent prognosis (event-rate 3%). An incremental increase in event-rate was observed with increasing CAC-risk category or coronary stenosis severity. Finally, obstructive (50-70%) or severe CAD (>70%) was independently predictive of events (HR 11.10 [2.52;48.79] (P = .001), HR 15.16 [3.01;76.36] (P = .001)). Obstructive (50-70%) or severe CAD (>70%) provided increased value over baseline risk factors.

Conclusion

Coronary CTA provided prognostic value in diabetic patients without chest pain syndrome. Most importantly, the prognosis of patients with a normal CTA was excellent.

     

Quantitation of left ventricular ejection fraction reserve from early gated regadenoson stress Tc-99m high-efficiency SPECT

Background

Ejection fraction (EF) reserve has been found to be a useful adjunct for identifying high risk coronary artery disease in cardiac positron emission tomography (PET). We aimed to evaluate EF reserve obtained from technetium-99m sestamibi (Tc-99m) high-efficiency (HE) SPECT.

Methods

Fifty patients (mean age 69 years) undergoing regadenoson same-day rest (8-11 mCi)/stress (32-42 mCi) Tc-99m gated HE SPECT were enrolled. Stress imaging was started 1 minute after sequential intravenous regadenoson .4 mg and Tc-99m injections, and was composed of five 2 minutes supine gated acquisitions followed by two 4 minutes supine and upright images. Ischemic total perfusion deficit (ITPD) ≥5 % was considered as significant ischemia.

Results

Significantly lower mean EF reserve was obtained in the 5th and 9th minute after regadenoson bolus in patients with significant ischemia vs patients without (5th minute: ?4.2 ± 4.6% vs 1.3 ± 6.6%, P = .006; 9th minute: ?2.7 ± 4.8% vs 2.0 ± 6.6%, P = .03).

Conclusions

Negative EF reserve obtained between 5th and 9th minutes of regadenoson stress demonstrated best concordance with significant ischemia and may be a promising tool for detection of transient ischemic functional changes with Tc-99m HE-SPECT.

     

Relationship Between Coronary Contrast-Flow Quantitative Flow Ratio and Myocardial Ischemia Assessed by SPECT MPI

Purpose

A new method has been developed to calculate fractional flow reserve (FFR) from invasive coronary angiography, the so-called “contrast-flow quantitative flow ratio (cQFR)”. Recently, cQFR was compared to invasive FFR in intermediate coronary lesions showing an overall diagnostic accuracy of 85%. The purpose of this study was to investigate the relationship between cQFR and myocardial ischemia assessed by single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI).

Methods

Patients who underwent SPECT MPI and coronary angiography within 3 months were included. The cQFR computation was performed offline, using dedicated software. The cQFR computation was based on 3-dimensional quantitative coronary angiography (QCA) and computational fluid dynamics. The standard 17-segment model was used to determine the vascular territories. Myocardial ischemia was defined as a summed difference score ≥2 in a vascular territory. A cQFR of ≤0.80 was considered abnormal.

Results

Two hundred and twenty-four coronary arteries were analysed in 85 patients. Overall accuracy of cQFR to detect ischemia on SPECT MPI was 90%. In multivariable analysis, cQFR was independently associated with ischemia on SPECT MPI (OR per 0.01 decrease of cQFR: 1.10; 95% CI 1.04-1.18, p = 0.002), whereas clinical and QCA parameters were not. Furthermore, cQFR showed incremental value for the detection of ischemia compared to clinical and QCA parameters (global chi square 48.7 to 62.6; p <0.001).

Conclusions

A good relationship between cQFR and SPECT MPI was found. cQFR was independently associated with ischemia on SPECT MPI and showed incremental value to detect ischemia compared to clinical and QCA parameters.