Phase II safety and clinical comparison with single-photon emission computed tomography myocardial perfusion imaging for detection of coronary artery disease: flurpiridaz F 18 positron emission tomography

OBJECTIVES

This was a phase II trial to assess flurpiridaz F 18 for safety and compare its diagnostic performance for positron emission tomography (PET) myocardial perfusion imaging (MPI) with Tc-99m single-photon emission computed tomography (SPECT) MPI with regard to image quality, interpretative certainty, defect magnitude, and detection of coronary artery disease (CAD) (≥50% stenosis) on invasive coronary angiography (ICA).

BACKGROUND

In pre-clinical and phase I studies, flurpiridaz F 18 has shown characteristics of an essentially ideal MPI tracer.

METHODS

One hundred forty-three patients from 21 centers underwent rest-stress PET and Tc-99m SPECT MPI. Eighty-six patients underwent ICA, and 39 had low-likelihood of CAD. Images were scored by 3 independent, blinded readers.

RESULTS

A higher percentage of images were rated as excellent/good on PET versus SPECT on stress (99.2% vs. 88.5%, p < 0.01) and rest (96.9% vs. 66.4, p < 0.01) images. Diagnostic certainty of interpretation (percentage of cases with definitely abnormal/normal interpretation) was higher for PET versus SPECT (90.8% vs. 70.9%, p < 0.01). In 86 patients who underwent ICA, sensitivity of PET was higher than SPECT (78.8% vs. 61.5%, respectively, p = 0.02). Specificity was not significantly different (PET: 76.5% vs. SPECT: 73.5%). Receiver-operating characteristic curve area was 0.82 ± 0.05 for PET and 0.70 ± 0.06 for SPECT (p = 0.04). Normalcy rate was 89.7% with PET and 97.4% with SPECT (p = NS). In patients with CAD on ICA, the magnitude of reversible defects was greater with PET than SPECT (p = 0.008). Extensive safety assessment revealed that flurpiridaz F 18 was safe in this cohort.

CONCLUSIONS

In this phase 2 trial, PET MPI with flurpiridaz F 18 was safe and superior to SPECT MPI for image quality, interpretative certainty, and overall CAD diagnosis.

Association of epicardial fat, hypertension, subclinical coronary artery disease, and metabolic syndrome with left ventricular diastolic dysfunction

Epicardial fat is a metabolically active fat depot that is strongly associated with obesity, metabolic syndrome, and coronary artery disease (CAD). The relation of epicardial fat to diastolic function is unknown. We sought to (1) understand the relation of epicardial fat volume (EFV) to diastolic function and (2) understand the role of EFV in relation to potential risk factors (hypertension, subclinical CAD, and metabolic syndrome) of diastolic dysfunction in apparently healthy subjects with preserved systolic function and no history of CAD. We studied 110 consecutive subjects (65% men, 55 ± 13 years old, mean body mass index 28 ± 5 kg/m(2)) who underwent cardiac computed tomography and transthoracic echocardiography within 6 months as part of a self-referred health screening program. Exclusion criteria included history of CAD, significant valvular disease, systolic dysfunction (left ventricular ejection fraction <50%). Diastolic function was defined according to American Society of Echocardiography guidelines. EFV was measured using validated cardiac computed tomographic software by 2 independent cardiologists blinded to clinical and echocardiographic data. Hypertension and metabolic syndrome were present in 60% and 45%, respectively. Subclinical CAD was identified in 20% of the cohort. Diastolic dysfunction was present in 45 patients. EFV was an independent predictor of diastolic dysfunction, mean peak early diastolic mitral annular velocity, and ratio of early diastolic filling to peak early diastolic mitral annular velocity (p = 0.01, <0.0001, and 0.001, respectively) with incremental contribution to other clinical factors. In conclusion, EFV is an independent predictor of impaired diastolic function in apparently healthy overweight patients even after accounting for associated co-morbidities such as metabolic syndrome, hypertension, and subclinical CAD.

Prognostic value of quantitative high-speed myocardial perfusion imaging

BACKGROUND

We studied the prognostic value of fully automated quantitative analysis software applied to new solid-state, high-speed (HS) SPECT-myocardial perfusion imaging (MPI).

METHODS

1,613 consecutive patients undergoing exercise or adenosine HS-MPI were followed for 2.6 ± 0.5 years for all-cause mortality (ACM). Automated quantitative software was used to compute stress total perfusion deficit (sTPD) and was compared to semi-quantitative visual analysis. MPI was characterized as 0% (normal), 1%-4% (minimal perfusion defect), 5%-10% (mildly abnormal), and >10% (moderately/severely abnormal).

RESULTS

During follow-up, 79 patients died (4.9%). Annualized ACM increased with progressively increasing sTPD; 0% (0.87%), 1%-4% (1.94%), 5%-10% (3.10%), and >10% (5.33%) (log-rank P < .0001). While similar overall findings were observed with visual analysis, only sTPD demonstrated increased risk in patients with minimal perfusion defects. In multivariable analysis, sTPD > 10% was a mortality predictor (HR 3.03, 95% CI 1.30-7.09, P = .01). Adjusted mortality rate was substantial in adenosine MPI, but low in exercise MPI (9.0% vs 1.0%, P < .0001).

CONCLUSIONS

By quantitative analysis, ACM increases with increasing perfusion abnormality among patients undergoing stress HS-MPI. These findings confirm previous results obtained with visual analysis using conventional Anger camera imaging systems.

Reproducibility of myocardial perfusion reserve - variations in measurements from post processing using commercially available software

PURPOSE

Adenosine stress first pass cardiac magnetic resonance imaging (CMRI) is a rapidly evolving tool in the diagnosis of ischemic heart disease (IHD). The rest and stress first pass myocardial perfusion data may be interpreted using commercially available software for calculation of time intensity curves in order to generate a numeric value of the segmental or whole heart myocardial perfusion reserve index (MPRI). The objective of this study was to determine the inter- and intra-observer reliability of the data generated by standard commercially available software.

METHODS

Data from 20 adenosine stress CMRI (1.5 T) studies were analyzed using commercially available CAAS MRV 3.3 software (Pie Medical Imaging B.V., Netherlands) for calculation of the MPRI. The stress CMRI was performed using a standardized protocol in 20 women including 10 women with angina and the absence of obstructive CAD and 10 healthy volunteers. MPRI calculation was made in a standardized manner on separate occasions by two independent observers. A single observer repeated the calculation of MPRI three months later, without reference to the prior data. Basal, mid, and apical segments, for the whole myocardium, sub-endocardium, and sub-epicardium were analyzed. Intra-class correlation coefficients (ICC), repeatability coefficients (RC), and coefficients of variation (CoV) were determined.

RESULTS

The MPRI results by repeated software measurements were highly correlated, with potentially important variations in measurement observed. The myocardial inter-observer ICC was 0.80 (95% CI, 0.57, 0.92) with a CoV of 7.5%, and intra-observer ICC was 0.89 (95% CI, 0.77, 0.95) with a CoV of 3.6%. The mid-ventricular level MPRI was most reproducible, with intra-observer ICC at 0.91 (95% CI, 0.77, 0.97); intra-observer measurement was more reproducible than inter-observer measurement.

CONCLUSIONS

There is variation in measurement of MPRI observed in post processing of perfusion data when using a standardized approach and commercially available software. This has implications in the interpretation of data obtained for clinical and research purposes.

Coronary computed tomographic angiography as a gatekeeper to invasive diagnostic and surgical procedures: results from the multicenter CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: an International Multicenter) registry

OBJECTIVES

This study sought to examine patterns of follow-up invasive coronary angiography (ICA) and revascularization (REV) after coronary computed tomography angiography (CCTA).

BACKGROUND

CCTA is a noninvasive test that permits direct visualization of the extent and severity of coronary artery disease (CAD). Post-CCTA patterns of follow-up ICA and REV are incompletely defined.

METHODS

We examined 15,207 intermediate likelihood patients from 8 sites in 6 countries; these patients were without known CAD, underwent CCTA, and were followed up for 2.3 ± 1.2 years for all-cause mortality. Coronary artery stenosis was judged as obstructive when ≥50% stenosis was present. A multivariable logistic regression was used to estimate ICA use. A Cox proportional hazards model was used to estimate all-cause mortality.

RESULTS

During follow-up, ICA rates for patients with no CAD to mild CAD according to CCTA were low (2.5% and 8.3%), with similarly low rates of REV (0.3% and 2.5%). Most ICA procedures (79%) occurred ≤3 months of CCTA. Obstructive CAD was associated with higher rates of ICA and REV for 1-vessel (44.3% and 28.0%), 2-vessel (53.3% and 43.6%), and 3-vessel (69.4% and 66.8%) CAD, respectively. For patients with <50% stenosis, early ICA rates were elevated; over the entirety of follow-up, predictors of ICA were mild left main, mild proximal CAD, respectively, or higher coronary calcium scores. In patients with <50% stenosis, the relative hazard for death was 2.2 (p = 0.011) for ICA versus no ICA. Conversely, for patients with CAD, the relative hazard for death was 0.61 for ICA versus no ICA (p = 0.047).

CONCLUSIONS

These findings support the concept that CCTA may be used effectively as a gatekeeper to ICA.

All-cause mortality benefit of coronary revascularization vs. medical therapy in patients without known coronary artery disease undergoing coronary computed tomographic angiography: results from CONFIRM (COronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multicenter Registry)

AIMS

To date, the therapeutic benefit of revascularization vs. medical therapy for stable individuals undergoing invasive coronary angiography (ICA) based upon coronary computed tomographic angiography (CCTA) findings has not been examined.

METHODS AND RESULTS

We examined 15 223 patients without known coronary artery disease (CAD) undergoing CCTA from eight sites and six countries who were followed for median 2.1 years (interquartile range 1.4-3.3 years) for an endpoint of all-cause mortality. Obstructive CAD by CCTA was defined as a ≥50% luminal diameter stenosis in a major coronary artery. Patients were categorized as having high-risk CAD vs. non-high-risk CAD, with the former including patients with at least obstructive two-vessel CAD with proximal left anterior descending artery involvement, three-vessel CAD, and left main CAD. Death occurred in 185 (1.2%) patients. Patients were categorized into two treatment groups: revascularization (n = 1103; 2.2% mortality) and medical therapy (n = 14 120, 1.1% mortality). To account for non-randomized referral to revascularization, we created a propensity score developed by logistic regression to identify variables that influenced the decision to refer to revascularization. Within this model (C index 0.92, χ2 = 1248, P < 0.0001), obstructive CAD was the most influential factor for referral, followed by an interaction of obstructive CAD with pre-test likelihood of CAD (P = 0.0344). Within CCTA CAD groups, rates of revascularization increased from 3.8% for non-high-risk CAD to 51.2% high-risk CAD. In multivariable models, when compared with medical therapy, revascularization was associated with a survival advantage for patients with high-risk CAD [hazards ratio (HR) 0.38, 95% confidence interval 0.18-0.83], with no difference in survival for patients with non-high-risk CAD (HR 3.24, 95% CI 0.76-13.89) (P-value for interaction = 0.03).

CONCLUSION

In an intermediate-term follow-up, coronary revascularization is associated with a survival benefit in patients with high-risk CAD by CCTA, with no apparent benefit of revascularization in patients with lesser forms of CAD.

Diagnostic accuracy of fractional flow reserve from anatomic CT angiography

CONTEXT

Coronary computed tomographic (CT) angiography is a noninvasive anatomic test for diagnosis of coronary stenosis that does not determine whether a stenosis causes ischemia. In contrast, fractional flow reserve (FFR) is a physiologic measure of coronary stenosis expressing the amount of coronary flow still attainable despite the presence of a stenosis, but it requires an invasive procedure. Noninvasive FFR computed from CT (FFR(CT)) is a novel method for determining the physiologic significance of coronary artery disease (CAD), but its ability to identify ischemia has not been adequately examined to date.

OBJECTIVE

To assess the diagnostic performance of FFR(CT) plus CT for diagnosis of hemodynamically significant coronary stenosis.

DESIGN, SETTING, AND PATIENTS

Multicenter diagnostic performance study involving 252 stable patients with suspected or known CAD from 17 centers in 5 countries who underwent CT, invasive coronary angiography (ICA), FFR, and FFR(CT) between October 2010 and October 2011. Computed tomography, ICA, FFR, and FFR(CT) were interpreted in blinded fashion by independent core laboratories. Accuracy of FFR(CT) plus CT for diagnosis of ischemia was compared with an invasive FFR reference standard. Ischemia was defined by an FFR or FFR(CT) of 0.80 or less, while anatomically obstructive CAD was defined by a stenosis of 50% or larger on CT and ICA.

MAIN OUTCOME MEASURES

The primary study outcome assessed whether FFR(CT) plus CT could improve the per-patient diagnostic accuracy such that the lower boundary of the 1-sided 95% confidence interval of this estimate exceeded 70%.

RESULTS

Among study participants, 137 (54.4%) had an abnormal FFR determined by ICA. On a per-patient basis, diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of FFR(CT) plus CT were 73% (95% CI, 67%-78%), 90% (95% CI, 84%-95%), 54% (95% CI, 46%-83%), 67% (95% CI, 60%-74%), and 84% (95% CI, 74%-90%), respectively. Compared with obstructive CAD diagnosed by CT alone (area under the receiver operating characteristic curve [AUC], 0.68; 95% CI, 0.62-0.74), FFR(CT) was associated with improved discrimination (AUC, 0.81; 95% CI, 0.75-0.86; P < .001).

CONCLUSION

Although the study did not achieve its prespecified primary outcome goal for the level of per-patient diagnostic accuracy, use of noninvasive FFR(CT) plus CT among stable patients with suspected or known CAD was associated with improved diagnostic accuracy and discrimination vs CT alone for the diagnosis of hemodynamically significant CAD when FFR determined at the time of ICA was the reference standard.

Statins use and coronary artery plaque composition: results from the International Multicenter CONFIRM Registry

OBJECTIVE

The effect of statins on coronary artery plaque features beyond stenosis severity is not known. Coronary CT angiography (CCTA) is a novel non-invasive method that permits direct visualization of coronary atherosclerotic features, including plaque composition. We evaluated the association of statin use to coronary plaque composition type in patients without known coronary artery disease (CAD) undergoing CCTA.

METHODS

From consecutive individuals, we identified 6673 individuals (2413 on statin therapy and 4260 not on statin therapy) with no known CAD and available statin use status. We studied the relationship between statin use and the presence and extent of specific plaque composition types, which was graded as non-calcified (NCP), mixed (MP), or calcified (CP) plaque.

RESULTS

The mean age was 59 ± 11 (55% male). Compared to the individuals not taking statins, those taking statins had higher prevalence of risk factors and obstructive CAD. In multivariable analyses, statin use was associated with increased the presence of MP [odds ratio (OR) 1.46, 95% confidence interval (CI) 1.27-1.68), p < 0.001] and CP (OR 1.54, 95% CI 1.36-1.74, p < 0.001), but not NCP (OR 1.11, 95% CI 0.96-1.29, p = 0.1). Further, in multivariable analyses, statin use was associated with increasing numbers of coronary segments possessing MP (OR 1.52, 95% CI 1.34-1.73, p < 0.001) and CP (OR 1.52, 95% CI 1.36-1.70, p < 0.001), but not coronary segments with NCP (OR 1.09, 95% CI 0.94-1.25, p = 0.2).

CONCLUSION

Statin use is associated with an increased prevalence and extent of coronary plaques possessing calcium. The longitudinal effect of statins on coronary plaque composition warrants further investigation.

Body mass index and the prevalence, severity, and risk of coronary artery disease: an international multicentre study of 13,874 patients

AIMS

Obesity is associated with the presence of coronary artery disease (CAD) risk factors and cardiovascular events. We examined the relationship between body mass index (BMI) and the presence, extent, severity, and risk of CAD in patients referred for coronary computed tomographic angiography (CCTA).

METHODS AND RESULTS

We evaluated 13,874 patients from a prospective, international, multicentre registry of individuals without known CAD undergoing CCTA. We compared risk factors, CAD findings, and risk of all-cause mortality and non-fatal myocardial infarction (MI) amongst individuals with underweight (18.5-20.0 kg/m(2)), normal (20.1-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), and obese (≥30 kg/m(2)) BMI. The mean follow-up was 2.4 ± 1.2 years with 143 deaths and 193 MIs. Among underweight, normal weight, overweight, and obese individuals, there was increasing prevalence of diabetes (7 vs.10% vs. 12 vs. 19%), hypertension (37 vs. 40% vs. 46 vs. 59%), and hyperlipidaemia (48 vs. 52% vs. 56 vs. 56%; P < 0.001 for trend). After multivariable adjustment, BMI was positively associated with the prevalence of any CAD [odds ratio (OR) 1.25 per +5 kg/m(2), 95% confidence interval (CI): 1.20-1.30, P < 0.001] and obstructive (≥50% stenosis) CAD (OR: 1.13 per +5 kg/m(2), 95% CI: 1.08-1.19, P < 0.001); a higher BMI was also associated with an increased number of segments with plaque (+0.26 segments per +5 kg/m(2), 95% CI: 0.22-0.30, P < 0.001). Larger BMI categories were associated with an increase in all-cause mortality (P = 0.004), but no difference in non-fatal MI. After multivariable adjustment, a higher BMI was independently associated with increased risk of MI (hazards ratio: 1.28 per +5 kg/m(2), 95% CI: 1.12-1.45, P < 0.001).

CONCLUSIONS

Amongst patients with suspected CAD referred for CCTA, individuals with increased BMI have greater prevalence, extent, and severity of CAD that is not fully explained by the presence of traditional risk factors. A higher BMI is independently associated with increased risk of intermediate-term risk of myocardial infarction.

Cardiologist concordance with the American College of Cardiology appropriate use criteria for cardiac testing in patients with coronary artery disease

The American College of Cardiology Appropriate Use Criteria (AUC) were developed to guide use of myocardial perfusion single-photon emission computed tomography (MPS), stress echocardiography, and cardiac computed tomographic angiography (CCTA). To date, cardiologist application of AUC from a patient-based multiprocedure perspective has not been evaluated. A Web-based survey of 15 clinical vignettes spanning a wide spectrum of indications for MPS, STE, and CCTA in coronary artery disease was administered to cardiologists who rated the ordered test as appropriate, inappropriate, or uncertain by AUC application and suggested a preferred alternative imaging procedure, if any. In total 129 cardiologists responded to the survey (mean age 49.5 years, board certification for MPS 65%, echocardiography 39%, CCTA 32%). Cardiologists agreed with published AUC ratings 65% of the time, with differences in all categories (appropriate, 50% vs 53%; inappropriate, 42% vs 20%; uncertain, 9% vs 27%, p <0.0001 for all comparisons). Physician age, practice type, or board certification in MPS or echocardiography had no effect on concordance with AUC ratings, with slightly higher agreement for those board certified in CCTA (68% vs 64%, p = 0.04). Cardiologist procedure preference was positively associated with active clinical interpretation of MPS and CCTA (p = 0.03 for the 2 comparisons) but not for ownership of the respective imaging equipment. In conclusion, cardiologist agreement with published AUC ratings is generally high, although physicians classify more uncertain indications as inappropriate. Active clinical interpretation of a procedure contributes most to increased procedure preference.

Baseline stress myocardial perfusion imaging results and outcomes in patients with stable ischemic heart disease randomized to optimal medical therapy with or without percutaneous coronary intervention

BACKGROUND

The COURAGE trial reported similar clinical outcomes for patients with stable ischemic heart disease (SIHD) receiving optimal medical therapy (OMT) with or without percutaneous coronary intervention (PCI). The current post hoc substudy analysis examined the relationship between baseline stress myocardial ischemia and clinical outcomes based on randomized treatment assignment.

METHODS

A total of 1,381 randomized patients (OMT n = 699, PCI + OMT n = 682) underwent baseline stress myocardial perfusion single-photon emission computed tomographic imaging. Site investigators interpreted the extent of ischemia by the number of ischemic segments using a 6-segment myocardial model. Patients were divided into those with no to mild (<3 ischemic segments) and moderate to severe ischemia (≥ 3 ischemic segments). Cox proportional hazards models were calculated to assess time to the primary end point of death or myocardial infarction.

RESULTS

At baseline, moderate to severe ischemia occurred in more than one-quarter of patients (n = 468), and the incidence was comparable in both treatment groups (P = .36). The primary end point, death or myocardial infarction, was similar in the OMT and PCI + OMT treatment groups for no to mild (18% and 19%, P = .92) and moderate to severe ischemia (19% and 22%, P = .53, interaction P value = .65). There was no gradient increase in events for the overall cohort with the extent of ischemia.

CONCLUSIONS

From the COURAGE trial post hoc substudy, the extent of site-defined ischemia did not predict adverse events and did not alter treatment effectiveness. Currently, evidence supports equipoise as to whether the extent and severity of ischemia impact on therapeutic effectiveness.

Differences in prevalence, extent, severity, and prognosis of coronary artery disease among patients with and without diabetes undergoing coronary computed tomography angiography: results from 10,110 individuals from the CONFIRM (COronary CT Angiography EvaluatioN For Clinical Outcomes): an InteRnational Multicenter Registry

OBJECTIVE

We examined the prevalence, extent, severity, and prognosis of coronary artery disease (CAD) in individuals with and without diabetes (DM) who are similar in CAD risk factors.

RESEARCH DESIGN AND METHODS

We identified 23,643 consecutive individuals without known CAD undergoing coronary computed tomography angiography. A total of 3,370 DM individuals were propensity matched in a 1-to-2 fashion to 6,740 unique non-DM individuals. CAD was defined as none, nonobstructive (1-49% stenosis), or obstructive (≥ 50% stenosis). All-cause mortality was assessed by risk-adjusted Cox proportional hazards models.

RESULTS

At a 2.2-year follow-up, 108 (3.2%) and 115 (1.7%) deaths occurred among DM and non-DM individuals, respectively. Compared with non-DM individuals, DM individuals possessed higher rates of obstructive CAD (37 vs. 27%) and lower rates of having normal arteries (28 vs. 36%) (P < 0.0001). CAD extent was higher for DM versus non-DM individuals for obstructive one-vessel disease (19 vs. 14%), two-vessel disease (9 vs. 7%), and three-vessel disease (9 vs. 5%) (P < 0.0001 for comparison), with higher per-segment stenosis in the proximal and mid-segments of every coronary artery (P < 0.001 for all). Compared with non-DM individuals with no CAD, risk of mortality for DM individuals was higher for those with no CAD (hazard ratio 3.63 [95% CI 1.67-7.91]; P = 0.001), nonobstructive CAD (5.25 [2.56-10.8]; P < 0.001), one-vessel disease (6.39 [2.98-13.7]; P < 0.0001), two-vessel disease (12.33 [5.622-27.1]; P < 0.0001), and three-vessel disease (13.25 [6.15-28.6]; P < 0.0001).

CONCLUSIONS

Compared with matched non-DM individuals, DM individuals possess higher prevalence, extent, and severity of CAD. At comparable levels of CAD, DM individuals experience higher risk of mortality compared with non-DM individuals.

What have we learned from CONFIRM? Prognostic implications from a prospective multicenter international observational cohort study of consecutive patients undergoing coronary computed tomographic angiography

Coronary computed tomographic angiography (CCTA) employing CT scanners of 64-detector rows or greater represents a novel non-invasive method for detection of coronary artery disease (CAD), providing excellent diagnostic information when compared to invasive angiography. In addition to its high diagnostic performance, prior studies have shown that CCTA can provide important prognostic information, although these prior studies have been generally limited to small cohorts at single centers. The Coronary CT Angiography EVALUATION FOR CLINICAL OUTCOMES: An International Multicenter registry, or CONFIRM, is a large, prospective, multinational, dynamic observational cohort study of patients undergoing CCTA. This registry currently represents more than 32,000 consecutive adults suspected of having CAD who underwent ≥ 64-detector row CCTA at 12 centers in 6 countries between 2005 and 2009. Based on its large sample size and adequate statistical power, the data derived from CONFIRM registry have and will continue to provide key answers to many important topics regarding CCTA. Based on its multisite international national design, the results derived from CONFIRM should be considered as more generalizable than prior smaller single-center studies. This article summarizes the current status of several studies from CONFIRM registry.

Coronary computed tomographic angiography and risk of all-cause mortality and nonfatal myocardial infarction in subjects without chest pain syndrome from the CONFIRM Registry (coronary CT angiography evaluation for clinical outcomes: an international multicenter registry)

BACKGROUND

The predictive value of coronary computed tomographic angiography (cCTA) in subjects without chest pain syndrome (CPS) has not been established. We investigated the prognostic value of coronary artery disease detection by cCTA and determined the incremental risk stratification benefit of cCTA findings compared with clinical risk factor scoring and coronary artery calcium scoring (CACS) for individuals without CPS.

METHODS AND RESULTS

An open-label, 12-center, 6-country observational registry of 27 125 consecutive patients undergoing cCTA and CACS was queried, and 7590 individuals without CPS or history of coronary artery disease met the inclusion criteria. All-cause mortality and the composite of all-cause mortality and nonfatal myocardial infarction were measured. During a median follow-up of 24 months (interquartile range, 18-35 months), all-cause mortality occurred in 136 individuals. After risk adjustment, compared with individuals without evidence of coronary artery disease by cCTA, individuals with obstructive 2- and 3-vessel disease or left main coronary artery disease experienced higher rates of death and composite outcome (P<0.05 for both). Both CACS and cCTA significantly improved the performance of standard risk factor prediction models for all-cause mortality and the composite outcome (likelihood ratio P<0.05 for all), but the incremental discriminatory value associated with their inclusion was more pronounced for the composite outcome and for CACS (C statistic for model with risk factors only was 0.71; for risk factors plus CACS, 0.75; for risk factors plus CACS plus cCTA, 0.77). The net reclassification improvement resulting from the addition of cCTA to a model based on standard risk factors and CACS was negligible.

CONCLUSIONS

Although the prognosis for individuals without CPS is stratified by cCTA, the additional risk-predictive advantage by cCTA is not clinically meaningful compared with a risk model based on CACS. Therefore, at present, the application of cCTA for risk assessment of individuals without CPS should not be justified.

Automatic alignment of myocardial perfusion PET and 64-slice coronary CT angiography on hybrid PET/CT

BACKGROUND

Hybrid PET/CT allows for acquisition of cardiac PET and coronary CT angiography (CCTA) in one session. However, PET and CCTA are acquired with differing breathing protocols and require software registration. We aimed to validate automatic correction for breathing misalignment between PET and CCTA acquired on hybrid scanner.

METHODS

Single-session hybrid PET/CT studies of rest/stress (13)N-ammonia PET and CCTA in 32 consecutive patients were considered. Automated registration of PET left ventricular (LV) surfaces with CCTA volumes was evaluated by comparing with expert manual alignment by two observers.

RESULTS

The average initial misalignments between the position of LV on PET and CCTA were 27.2 ± 11.8, 13.3 ± 11.5, and 14.3 ± 9.1 mm in x, y, and z axes on rest, and 26.3 ± 10.2, 11.1 ± 9.5, and 11.7 ± 7.1 mm in x, y, and z axes on stress, respectively. The automated PET-CCTA co-registration had 95% agreement as judged visually. Compared with expert manual alignment, the translation errors of the algorithm were 5.3 ± 2.8 mm (rest) and 6.0 ± 3.5 mm (stress). 3D visualization of combined coronary vessel anatomy and hypoperfusion from PET could be made without further manual adjustments.

CONCLUSION

Software co-registration of CCTA and PET myocardial perfusion imaging on hybrid PET/CT scanners is necessary, but can be performed automatically, facilitating integrated 3D display on PET/CT.