Impact of complete revascularization in the IschemiaTrial

BACKGROUND: Anatomic complete revascularization (ACR) and functional complete revascularization (FCR) have been associated with reduced death and myocardial infarction (MI) in some prior studies. The impact of complete revascularization (CR) in patients undergoing an invasive (INV) compared with a conservative (CON) management strategy has not been reported. OBJECTIVES: Among patients with chronic coronary disease without prior coronary artery bypass grafting randomized to INV vs CON management in the ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) trial, we examined the following: 1) the outcomes of ACR and FCR compared with incomplete revascularization; and 2) the potential impact of achieving CR in all INV patients compared with CON management. METHODS: ACR and FCR in the INV group were assessed at an independent core laboratory. Multivariable-adjusted outcomes of CR were examined in INV patients. Inverse probability weighted modeling was then performed to estimate the treatment effect had CR been achieved in all INV patients compared with CON management. RESULTS: ACR and FCR were achieved in 43.4% and 58.4% of 1,824 INV patients. ACR was associated with reduced 4-year rates of cardiovascular death or MI compared with incomplete revascularization. By inverse probability weighted modeling, ACR in all 2,296 INV patients compared with 2,498 CON patients was associated with a lower 4-year rate of cardiovascular death or MI (difference -3.5; 95% CI: -7.2% to 0.0%). In comparison, the event rate difference of cardiovascular death or MI for INV minus CON in the overall ISCHEMIA trial was -2.4%. Results were similar but less pronounced with FCR. CONCLUSIONS: The outcomes of an INV strategy may be improved if CR (especially ACR) is achieved. (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches [ISCHEMIA]; NCT01471522).

Handling missing values in machine learning to predict patient-specific risk of adverse cardiac events: Insights from REFINE SPECT registry.

BACKGROUND: Machine learning (ML) models can improve prediction of major adverse cardiovascular events (MACE), but in clinical practice some values may be missing. We evaluated the influence of missing values in ML models for patient-specific prediction of MACE risk. METHODS: We included 20,179 patients from the multicenter REFINE SPECT registry with MACE follow-up data. We evaluated seven methods for handling missing values: 1) removal of variables with missing values (ML-Remove), 2) imputation with median and unique category for continuous and categorical variables, respectively (ML-Traditional), 3) unique category for missing variables (ML-Unique), 4) cluster-based imputation (ML-Cluster), 5) regression-based imputation (ML-Regression), 6) missRanger imputation (ML-MR), and 7) multiple imputation (ML-MICE). We trained ML models with full data and simulated missing values in testing patients. Prediction performance was evaluated using area under the receiver-operating characteristic curve (AUC) and compared with a model without missing values (ML-All), expert visual diagnosis and total perfusion deficit (TPD). RESULTS: During mean follow-up of 4.7 ± 1.5 years, 3,541 patients experienced at least one MACE (3.7% annualized risk). ML-All (reference model-no missing values) had AUC 0.799 for MACE risk prediction. All seven models with missing values had lower AUC (ML-Remove: 0.778, ML-MICE: 0.774, ML-Cluster: 0.771, ML-Traditional: 0.771, ML-Regression: 0.770, ML-MR: 0.766, and ML-Unique: 0.766; p < 0.01 for ML-Remove vs remaining methods). Stress TPD (AUC 0.698) and visual diagnosis (0.681) had the lowest AUCs. CONCLUSION: Missing values reduce the accuracy of ML models when predicting MACE risk. Removing variables with missing values and retraining the model may yield superior patient-level prediction performance.

Outcomes in the ISCHEMIA Trial Based on Coronary Artery Disease and Ischemia Severity

BACKGROUND: The ISCHEMIA trial (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches) postulated that patients with stable coronary artery disease (CAD) and moderate or severe ischemia would benefit from revascularization. We investigated the relationship between severity of CAD and ischemia and trial outcomes, overall and by management strategy. METHODS: In total, 5179 patients with moderate or severe ischemia were randomized to an initial invasive or conservative management strategy. Blinded, core laboratory­interpreted coronary computed tomographic angiography was used to assess anatomic eligibility for randomization. Extent and severity of CAD were classified with the modified Duke Prognostic Index (n=2475, 48%). Ischemia severity was interpreted by independent core laboratories (nuclear, echocardiography, magnetic resonance imaging, exercise tolerance testing, n=5105, 99%). We compared 4-year event rates across subgroups defined by severity of ischemia and CAD. The primary end point for this analysis was all-cause mortality. Secondary end points were myocardial infarction (MI), cardiovascular death or MI, and the trial primary end point (cardiovascular death, MI, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest). RESULTS: Relative to mild/no ischemia, neither moderate ischemia nor severe ischemia was associated with increased mortality (moderate ischemia hazard ratio [HR], 0.89 [95% CI, 0.61­1.30]; severe ischemia HR, 0.83 [95% CI, 0.57­1.21]; P=0.33). Nonfatal MI rates increased with worsening ischemia severity (HR for moderate ischemia, 1.20 [95% CI, 0.86­1.69] versus mild/no ischemia; HR for severe ischemia, 1.37 [95% CI, 0.98­1.91]; P=0.04 for trend, P=NS after adjustment for CAD). Increasing CAD severity was associated with death (HR, 2.72 [95% CI, 1.06­6.98]) and MI (HR, 3.78 [95% CI, 1.63­8.78]) for the most versus least severe CAD subgroup. Ischemia severity did not identify a subgroup with treatment benefit on mortality, MI, the trial primary end point, or cardiovascular death or MI. In the most severe CAD subgroup (n=659), the 4-year rate of cardiovascular death or MI was lower in the invasive strategy group (difference, 6.3% [95% CI, 0.2%­12.4%]), but 4-year all-cause mortality was similar. CONCLUSIONS: Ischemia severity was not associated with increased risk after adjustment for CAD severity. More severe CAD was associated with increased risk. Invasive management did not lower all-cause mortality at 4 years in any ischemia or CAD subgroup.

Association of Cardiovascular Disease Risk Factor Burden With Progression of Coronary Atherosclerosis Assessed by Serial Coronary Computed Tomographic Angiography.

Importance: Several studies have reported that the progression of coronary atherosclerosis, as measured by serial coronary computed tomographic (CT) angiography, is associated with the risk of future cardiovascular events. However, the cumulative consequences of multiple risk factors for plaque progression and the development of adverse plaque characteristics have not been well characterized. Objectives: To examine the association of cardiovascular risk factor burden, as assessed by atherosclerotic cardiovascular disease (ASCVD) risk score, with the progression of coronary atherosclerosis and the development of adverse plaque characteristics. Design, Setting, and Participants: This cohort study is a subgroup analysis of participant data from the prospective observational Progression of Atherosclerotic Plaque Determined by Computed Tomographic Angiography Imaging (PARADIGM) study, which evaluated the association between serial coronary CT angiography findings and clinical presentation. The PARADIGM international multicenter registry, which includes 13 centers in 7 countries (Brazil, Canada, Germany, Italy, Portugal, South Korea, and the US), was used to identify 1005 adult patients without known coronary artery disease who underwent serial coronary CT angiography scans (median interscan interval, 3.3 years; interquartile range [IQR], 2.6-4.8 years) between December 24, 2003, and December 16, 2015. Based on the 10-year ASCVD risk score, the cardiovascular risk factor burden was classified as low (<7.5%), intermediate (7.5%-20.0%), or high (>20.0%). Data were analyzed from February 8, 2019, to April 17, 2020. Exposures: Association of baseline ASCVD risk burden with plaque progression. Main Outcomes and Measures: Noncalcified plaque, calcified plaque, and total plaque volumes (mm3) were measured. Noncalcified plaque was subclassified using predefined Hounsfield unit thresholds for fibrous, fibrofatty, and low-attenuation plaque. The percent atheroma volume (PAV) was defined as plaque volume divided by vessel volume. Adverse plaque characteristics were defined as the presence of positive remodeling, low-attenuation plaque, or spotty calcification. Results: In total, 1005 patients (mean [SD] age, 60 [8] years; 575 men [57.2%]) were included in the analysis. Of those, 463 patients (46.1%) had a low 10-year ASCVD risk score (low-risk group), 373 patients (37.1%) had an intermediate ASCVD risk score (intermediate-risk group), and 169 patients (16.8%) had a high ASCVD risk score (high-risk group). The annualized progression rate of PAV for total plaque, calcified plaque, and noncalcified plaque was associated with increasing ASCVD risk (r = 0.26 for total plaque, r = 0.23 for calcified plaque, and r = 0.11 for noncalcified plaque; P < .001). The annualized PAV progression of total plaque, calcified plaque, and noncalcified plaque was significantly greater in the high-risk group compared with the low-risk and intermediate-risk groups (for total plaque, 0.99% vs 0.45% and 0.58%, respectively; P < .001; for calcified plaque, 0.61% vs 0.23% and 0.36%; P < .001; and for noncalcified plaque, 0.38%vs 0.22% and 0.23%; P = .01). When further subclassified by noncalcified plaque type, the annualized PAV progression of fibrofatty and low-attenuation plaque was greater in the high-risk group (0.09% and 0.02%, respectively) compared with the low- to intermediate-risk group (n = 836; 0.02% [P = .02] and 0.001% [P = .008], respectively). The interval development of adverse plaque characteristics was greater in the high-risk group compared with the low-risk and intermediate-risk groups (for new positive remodeling, 73 patients [43.2%] vs 151 patients [32.6%] and 133 patients [35.7%], respectively; P = .02; for new low-attenuation plaque, 26 patients [15.4%] vs 44 patients [9.5%] and 35 patients [9.4%]; P = .02; and for new spotty calcification, 37 patients [21.9%] vs 52 patients [11.2%] and 54 patients [14.5%]; P = .002). The progression of noncalcified plaque subclasses and the interval development of adverse plaque characteristics did not significantly differ between the low-risk and intermediate-risk groups. Conclusions and Relevance: Progression of coronary atherosclerosis occurred across all ASCVD risk groups and was associated with an increase in 10-year ASCVD risk. The progression of fibrofatty and low-attenuation plaques and the development of adverse plaque characteristics was greater in patients with a high risk of ASCVD.

Myocardial viability and long-term outcomes in ischemic cardiomyopathy

BACKGROUND: The role of assessment of myocardial viability in identifying patients with ischemic cardiomyopathy who might benefit from surgical revascularization remains controversial. Furthermore, although improvement in left ventricular function is one of the goals of revascularization, its relationship to subsequent outcomes is unclear. METHODS: Among 601 patients who had coronary artery disease that was amenable to coronaryartery bypass grafting (CABG) and who had a left ventricular ejection fraction of 35% or lower, we prospectively assessed myocardial viability using single-photonemission computed tomography, dobutamine echocardiography, or both. Patients were randomly assigned to undergo CABG and receive medical therapy or to receive medical therapy alone. Left ventricular ejection fraction was measured at baseline and after 4 months of follow-up in 318 patients. The primary end point was death from any cause. The median duration of follow-up was 10.4 years. RESULTS: CABG plus medical therapy was associated with a lower incidence of death from any cause than medical therapy alone (182 deaths among 298 patients in the CABG group vs. 209 deaths among 303 patients in the medical-therapy group; adjusted hazard ratio, 0.73; 95% confidence interval, 0.60 to 0.90). However, no significant interaction was observed between the presence or absence of myocardial viability and the beneficial effect of CABG plus medical therapy over medical therapy alone (P=0.34 for interaction). An increase in left ventricular ejection fraction was observed only among patients with myocardial viability, irrespective of treatment assignment. There was no association between changes in left ventricular ejection fraction and subsequent death. CONCLUSIONS: The findings of this study do not support the concept that myocardial viability is associated with a long-term benefit of CABG in patients with ischemic cardiomyopathy. The presence of viable myocardium was associated with improvement in left ventricular systolic function, irrespective of treatment, but such improvement was not related to long-term survival. (Funded by the National Institutes of Health; STICH ClinicalTrials.gov number, NCT00023595.). (AU)

Quantification of Coronary Atherosclerosis in the Assessment of Coronary Artery Disease.

BACKGROUND: Diagnosis of coronary artery disease and management strategies have relied solely on the presence of diameter stenosis ≥50%. We assessed whether direct quantification of plaque burden (PB) and plaque characteristics assessed by coronary computed tomography angiography could provide additional value in terms of predicting rapid plaque progression. METHODS AND RESULTS: From a 13-center, 7-country prospective observational registry, 1345 patients (60.4±9.4 years old; 57.1% male) who underwent repeated coronary computed tomography angiography >2 years apart were enrolled. For conventional angiographic analysis, the presence of stenosis ≥50%, number of vessel involved, segment involvement score, and the presence of high-risk plaque feature were determined. For quantitative analyses, PB and annual change in PB (△PB/y) in the entire coronary tree were assessed. Clinical outcomes (cardiac death, nonfatal myocardial infarction, and coronary revascularization) were recorded. Rapid progressors, defined as a patient with ≥median value of △PB/y (0.33%/y), were older, more frequently male, and had more clinical risk factors than nonrapid progressors (all P<0.05). After risk adjustment, addition of baseline PB improved prediction of rapid progression to each angiographic assessment of coronary artery disease, and the presence of high-risk plaque further improved the predictive performance (all P<0.001). For prediction of adverse outcomes, adding both baseline PB and △PB/y showed best predictive performance (C statistics, 0.763; P<0.001). CONCLUSIONS: Direct quantification of atherosclerotic PB in addition to conventional angiographic assessment of coronary artery disease might be beneficial for improving risk stratification of coronary artery disease. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02803411.

Effects of Statins on Coronary Atherosclerotic Plaques: The PARADIGM Study.

OBJECTIVES: This study sought to describe the impact of statins on individual coronary atherosclerotic plaques. BACKGROUND: Although statins reduce the risk of major adverse cardiovascular events, their long-term effects on coronary atherosclerosis remain unclear. METHODS: We performed a prospective, multinational study consisting of a registry of consecutive patients without history of coronary artery disease who underwent serial coronary computed tomography angiography at an interscan interval of ≥2 years. Atherosclerotic plaques were quantitatively analyzed for percent diameter stenosis (%DS), percent atheroma volume (PAV), plaque composition, and presence of high-risk plaque (HRP), defined by the presence of ≥2 features of low-attenuation plaque, positive arterial remodeling, or spotty calcifications. RESULTS: Among 1,255 patients (60 ± 9 years of age; 57% men), 1,079 coronary artery lesions were evaluated in statin-naive patients (n = 474), and 2,496 coronary artery lesions were evaluated in statin-taking patients (n = 781). Compared with lesions in statin-naive patients, those in statin-taking patients displayed a slower rate of overall PAV progression (1.76 ± 2.40% per year vs. 2.04 ± 2.37% per year, respectively; p = 0.002) but more rapid progression of calcified PAV (1.27 ± 1.54% per year vs. 0.98 ± 1.27% per year, respectively; p < 0.001). Progression of noncalcified PAV and annual incidence of new HRP features were lower in lesions in statin-taking patients (0.49 ± 2.39% per year vs. 1.06 ± 2.42% per year and 0.9% per year vs. 1.6% per year, respectively; all p < 0.001). The rates of progression to >50% DS were not different (1.0% vs. 1.4%, respectively; p > 0.05). Statins were associated with a 21% reduction in annualized total PAV progression above the median and 35% reduction in HRP development. CONCLUSIONS: Statins were associated with slower progression of overall coronary atherosclerosis volume, with increased plaque calcification and reduction of high-risk plaque features. Statins did not affect the progression of percentage of stenosis severity of coronary artery lesions but induced phenotypic plaque transformation. (Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography Imaging [PARADIGM]; NCT02803411).

Myocardial viability and impact of surgical ventricular reconstructionon outcomes of patients with severe left ventricular dysfunctionundergoing coronary artery bypass surgery: results of the surgical treatment for ischemic heart failure trial

Objectives: In the Surgical Treatment for Ischemic Heart Failure trial, surgical ventricular reconstruction pluscoronary artery bypass surgery was not associated with a reduction in the rate of death or cardiac hospitalizationcompared with bypass alone. We hypothesized that the absence of viable myocardium identifies patients withcoronary artery disease and left ventricular dysfunction who have a greater benefit with coronary artery bypassgraft surgery and surgical ventricular reconstruction compared with bypass alone.Methods: Myocardial viability was assessed by single photon computed tomography in 267 of the 1000 patientsrandomized to bypass or bypass plus surgical ventricular reconstruction in the Surgical Treatment for IschemicHeart Failure. Myocardial viability was assessed on a per patient basis and regionally according to prespecifiedcriteria.Results: At 3 years, there was no difference in mortality or the combined outcome of death or cardiachospitalization between those with and without viability, and there was no significant interaction between thetype of surgery and the global viability status with respect to mortality or death plus cardiac hospitalization.Furthermore, there was no difference in mortality or death plus cardiac hospitalization between those withand without anterior wall or apical scar, and no significant interaction between the presence of scar in theseregions and the type of surgery with respect to mortality.Conclusions: In patients with coronary artery disease and severe regional left ventricular dysfunction,assessment of myocardial viability does not identify patients who will derive a mortality benefit from addingsurgical ventricular reconstruction to coronary artery bypass graft surgery.

Myocardial viability and impact of surgical ventricular reconstruction on outcomes of patients with severe left ventricular dysfunction undergoing coronary artery bypass surgery: results of the surgical treatment for ischemic heart failure trial

In the Surgical Treatment for Ischemic Heart Failure trial, surgical ventricular reconstruction plus coronary artery bypass surgery was not associated with a reduction in the rate of death or cardiac hospitalization compared with bypass alone. We hypothesized that the absence of viable myocardium identifies patients with coronary artery disease and left ventricular dysfunction who have a greater benefit with coronary artery bypass graft surgery and surgical ventricular reconstruction compared with bypass alone.MethodsMyocardial viability was assessed by single photon computed tomography in 267 of the 1000 patients randomized to bypass or bypass plus surgical ventricular reconstruction in the Surgical Treatment for Ischemic Heart Failure. Myocardial viability was assessed on a per patient basis and regionally according to prespecified criteria.ResultsAt 3 years, there was no difference in mortality or the combined outcome of death or cardiac hospitalization between those with and without viability, and there was no significant interaction between the type of surgery and the global viability status with respect to mortality or death plus cardiac hospitalization. Furthermore, there was no difference in mortality or death plus cardiac hospitalization between those with and without anterior wall or apical scar, and no significant interaction between the presence of scar in these regions and the type of surgery with respect to mortality.ConclusionsIn patients with coronary artery disease and severe regional left ventricular dysfunction, assessment of myocardial viability does not identify patients who will derive a mortality benefit from adding surgical ventricular reconstruction to coronary artery bypass graft surgery.

Myocardial viability and survival in ischemic left ventricular dysfunction

Background The assessment of myocardial viability has been used to identify patients withcoronary artery disease and left ventricular dysfunction in whom coronary-arterybypass grafting (CABG) will provide a survival benefit. However, the efficacy of thisapproach is uncertain. Methods In a substudy of patients with coronary artery disease and left ventricular dysfunctionwho were enrolled in a randomized trial of medical therapy with or withoutCABG, we used single-photon-emission computed tomography (SPECT), dobutamineechocardiography, or both to assess myocardial viability on the basis of prespecifiedthresholds.ResultsAmong the 1212 patients enrolled in the randomized trial, 601 underwent assessmentof myocardial viability. Of these patients, we randomly assigned 298 to receivemedical therapy plus CABG and 303 to receive medical therapy alone. A total of 178of 487 patients with viable myocardium (37%) and 58 of 114 patients without viablemyocardium (51%) died (hazard ratio for death among patients with viable myocardium,0.64; 95% confidence interval [CI], 0.48 to 0.86; P = 0.003). However, afteradjustment for other baseline variables, this association with mortality was notsignificant (P = 0.21). There was no significant interaction between viability statusand treatment assignment with respect to mortality (P = 0.53).ConclusionsThe presence of viable myocardium was associated with a greater likelihood ofsurvival in patients with coronary artery disease and left ventricular dysfunction,but this relationship was not significant after adjustment for other baseline variables.The assessment of myocardial viability did not identify patients with a differentialsurvival benefit from CABG, as compared with medical therapy alone.(Funded by the National Heart, Lung, and Blood Institute; STICH ClinicalTrials.govnumber, NCT00023595.)

Functional impact of coronary stenosis observed on coronary computed tomography angiography: Comparison with ¹³N-ammonia PET.

BACKGROUND AND AIMS: We undertook this study to evaluate the functional impact of coronary abnormalities in patients with suspected coronary artery disease (CAD) by means of integrated positron emission tomography (PET) and coronary computed tomography angiography (CCTA) scan obtained on a hybrid state-of-the-art PET/CT scanner. METHODS: We studied 29 consecutive, patients with a clinically suspected intermediate risk for CAD, using a hybrid PET/CT 64 slice scanner. During a single scanning session, CCTA was performed for coronary anatomy evaluation, and a rest/adenosine stress (13)N-ammonia PET was performed for myocardial perfusion assessment in 3D mode with CT attenuation correction. RESULTS: Twenty four (82.7%) patients had atherosclerosis detected by CCTA; 15 patients had significant (≥50%) coronary stenoses and all 15 patients showed ischemia by PET; moreover, 10/15 patients had a Summed Stress Score >12.20/24 and 83.3% patients with atherosclerosis detected by CCTA showed ischemia by PET. Two of five patients with normal coronary arteries showed ischemia by PET. CCTA agreement in positive identification of PET ischemia was 91% and agreement in ruling out ischemia was 43%; PET agreement in detecting CCTA atherosclerosis was 83%, and agreement in ruling it out was 60%. CONCLUSIONS: We found a strong relation between significant coronary stenosis identified by CCTA and ischemia by PET. However, in cases with low-grade stenosis, PET scan can assess the functional significance of atherosclerotic abnormalities.

Thoracic aorta calcification detected by electron beam tomography predicts all-cause mortality.

BACKGROUND: The presence of coronary artery calcium (CAC) is an independent marker of increased risk of cardiovascular disease (CVD) events and mortality. However, the predictive value of thoracic aorta calcification (TAC), which can be additionally identified without further scanning during assessment of CAC, is unknown. METHODS: We followed a cohort of 8401 asymptomatic individuals (mean age: 53+/-10 years, 69% men) undergoing cardiac risk factor evaluation and TAC and CAC testing with electron beam computed tomography. Multivariable Cox proportional hazards models were developed to predict all-cause mortality based on the presence of TAC. RESULTS: During a median follow-up period of 5 years, 124 (1.5%) deaths were observed. Overall survival was 96.9% and 98.9% for those with and without detectable TAC, respectively (p<0.0001). Compared to those with no TAC, the hazard ratio for mortality in the presence of TAC was 3.25 (95% CI: 2.28-4.65, p<0.0001) in unadjusted analysis. After adjusting for age, gender, hypertension, dyslipidemia, diabetes mellitus, smoking and family history of premature coronary artery disease, and presence of CAC the relationship remained robust (HR 1.61, 95% CI: 1.10-2.27, p=0.015). Likelihood ratio chi(2) statistics demonstrated that the addition of TAC contributed significantly in predicting mortality to traditional risk factors alone (chi(2)=13.62, p=0.002) as well as risk factors+CAC (chi(2)=5.84, p=0.02) models. CONCLUSION: In conclusion, the presence of TAC was associated with all-cause mortality in our study; this relationship was independent of conventional CVD risk factors as well as the presence of CAC.