Myocardial Flow Reserve and Coronary Calcification in Prognosis of Patients With Suspected Coronary Artery Disease

Prognostic value of myocardial flow reserve by PET imaging in patients with suspected coronary artery disease: A systematic review and meta-analysis

Purpose

We performed a systematic review and meta-analysis of published studies evaluating the value of myocardial flow reserve (MFR) assessed by positron emission tomography (PET) imaging in predicting adverse cardiovascular events in patients with suspected coronary artery disease (CAD).

Material and methods

Studies published until December 2024 were identified by database search. We included studies evaluating MFR by PET imaging with data on adjusted hazard ratio (HR) for the occurrence of adverse cardiovascular events.

Results

We identified 8 eligible articles including 12.087 patients with a mean follow-up of 2.98 ± 0.69 years. The pooled HR for the occurrence of events was 2.19 (95 % CI 1.80-2.68) and no heterogeneity was observed. The pooled incidence rate ratio (IRR) was 3.26 (95 % CI 2.43-4.37) and the heterogeneity was 37.7 %. At meta-regression analysis no significant association was found between HR for adverse events and demographic and clinical variables considered.

Conclusion

MFR assessed by PET imaging is a valuable noninvasive prognostic indicator in the evaluation of patients with suspected CAD.

Correlation Analysis of Gut Microbiota Derivatives with Coronary Artery Disease Severity and Prognosis

Background

Previous research has highlighted a connection between gut microbiota derivatives and atherosclerosis. This study assesses the association between gut microbiota derivatives and coronary artery disease (CAD) to enhance CAD prevention and treatment strategies.

Methods

Patients presenting with suspected CAD were categorized into CAD and non-CAD groups. A propensity score matching analysis was performed to exclude confounding factors. Key differences in general characteristics and gut microbiota derivatives between these groups were also assessed. Additionally, the study explored the correlation between significant differences in the Gensini score and coronary flow reserve. Moreover, the potential of significant indicators to predict the diagnosis of coronary artery disease was analyzed.

Results

After propensity score matching, the concentrations of interleukin-6 (IL-6) (47.23 ± 7.45 vs. 39.56 ± 7.37; p < 0.001), lipopolysaccharide (LPS) (12.79 ± 2.07 vs. 11.71 ± 1.88; p = 0.031), high-sensitivity C-reactive protein (hs-CRP) (13.58 ± 2.62 vs. 11.57 ± 2.49; p = 0.002), phenylacetyl glutamine (PAGIn) (619.20 ± 119.33 vs. 555.64 ± 109.29; p = 0.029), and trimethylamine-N-oxide (TMAO) (13.01 ± 2.19 vs. 11.70 ± 1.78; p = 0.011) in the CAD group were significantly elevated compared to those in the non-CAD group. Conversely, the serum levels of glucagon-like peptide-1 (GLP-1) (7.74 ± 2.07 vs. 9.06 ± 2.11; p = 0.012) were notably lower in the CAD group than in the non-CAD group. A positive association was observed between the serum concentrations of IL-6 (r = 0.410; p < 0.001), hs-CRP (r = 0.317; p < 0.007), TMAO (r = 0.311; p < 0.008), and coronary Gensini score. Moreover, IL-6 (b = 1.769, 95% confidence interval (CI): 0.256-3.282; p = 0.023) and TMAO (b = 10.735, 95% CI: 4.883-16.588; p < 0.001) had a direct positive impact on the coronary Gensini score. The highest diagnostic value for CAD was observed when the IL-6 cut-off value was 45.17 (sensitivity 69.6%, specificity 73.1%, area under curve 0.770; 95% CI: 0.662-0.879; p < 0.001). Meanwhile, the highest diagnostic value for CAD was noted when the TMAO cut-off value was 12.44 (sensitivity 65.2%, specificity 76.9%, the area under the curve 0.689; 95% CI: 0.564-0.814; p = 0.008). Serum TMAO was negatively correlated with coronary flow reserve (CFR) in CAD patients (r = -0.593; p = 0.009).

Conclusions

These findings suggest that serum IL-6, LPS, hs-CRP, PAGIn, TMAO, and GLP-1 levels can be used as clinical markers for predicting CAD severity. Among these, IL-6, hs-CRP, and TMAO are identified as independent risk factors influencing the severity of CAD-elevated levels of IL-6 and TMAO exhibit predictive utility for CAD diagnosis. Furthermore, serum TMAO is a potential clinical marker for forecasting a CAD prognosis.

Hybrid cardiovascular imaging. A clinical consensus statement of the european association of nuclear medicine (EANM) and the european association of cardiovascular imaging (EACVI) of the ESC

Hybrid imaging consists of a combination of two or more imaging modalities, which equally contribute to image information. To date, hybrid cardiovascular imaging can be performed by either merging images acquired on different scanners, or with truly hybrid PET/CT and PET/MR scanners. The European Association of Nuclear Medicine (EANM), and the European Association of Cardiovascular Imaging (EACVI) of the European Society of Cardiology (ESC) aim to review clinical situations that may benefit from the use of hybrid cardiac imaging and provide advice on acquisition protocols providing the most relevant information to reach diagnosis in various clinical situations.

Reassessing the Role of Ischemia Imaging: Insights from the ISCHEMIA Trial

Ischemia imaging plays an important role in prognostication as well as guiding decision for revascularization with known CAD, as shown in multiple observational registries. However, results from the ISCHEMIA trial (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches) presented conflicting results, hinting at no survival benefit after revascularization in patients with moderate to severe ischemia on nuclear imaging. More recent analysis from the trial did, however, show decrease in cardiac mortality and increase in non-cardiac mortality following early revascularization. However, the ISCHEMIA trial has several limitations; most importantly, the trial design does not support a comparison between imaging modalities. Additionally, results of the trial do not apply to patients with previous CABG or ACS as they are exclusion criteria, which affects the diagnostic accuracy of nuclear stress imaging. Observational imaging registries offer better evidence about the accuracy of single-photon emission computed tomography (SPECT) and positron emission tomography (PET) in guiding revascularization for patients with ischemia. Results from ISCHEMIA trial can be used to guide management of patients with severe to moderate ischemia, provided they meet inclusion criteria. For those who do, shared decision-making is important to decide between invasive management or optimal medical therapy only.

Hybrid Imaging: Calcium Score and Myocardial Perfusion Imaging

Coronary heart disease (CHD) remains the top cause of death due to cardiovascular conditions worldwide, with someone suffering a myocardial infarction every 40 seconds. This highlights the importance of non-invasive imaging technologies like myocardial perfusion imaging (MPI), which are crucial for detecting coronary artery disease (CAD) early, even before symptoms appear. However, the reliance solely on MPI has shifted due to its limitations in definitively ruling out atherosclerosis, leading to the adoption of hybrid imaging techniques. Hybrid imaging combines computed tomography (CT) with MPI techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT). This integration, often within a single gantry system, enhances the diagnostic accuracy by allowing for attenuation correction (AC), acquisition of the coronary artery calcium score (CACS), and more precise tracing of radiotracer uptake. The built-in CT in modern MPI systems assists in these functions, which is essential for better diagnosis and risk assessment in patients. The addition of CACS to MPI, a method involving the assessment of calcified plaque in coronary arteries, notably enhances diagnostic and prognostic capabilities. CACS helps in identifying atherosclerosis and predicting potential cardiac events, facilitating personalized risk management and the initiation of tailored interventions like statins and aspirin. Such comprehensive imaging strategies not only improve the accuracy of detecting CAD but also help in stratifying patient risk more effectively. In this paper, we discuss how the incorporation of CAC into MPI protocols enhances the diagnostic sensitivity for detecting obstructive CAD, as evidenced by several studies where the addition of CAC to MPI has led to improved outcomes in diagnosing CAD. Moreover, CAC has been shown to unmask silent coronary atherosclerosis in patients with normal MPI results, highlighting its incremental diagnostic value. We will discuss the evolving role of hybrid imaging in guiding therapeutic decisions, particularly the use of statins for cardiovascular prevention. The integration of CAC assessment with MPI not only aids in the early detection and management of CAD but also optimizes therapeutic strategies, enhancing patient care through a more accurate and personalized approach. Such advancements underscore the need for further research to fully establish the benefits of combining CAC with MPI in the clinical assessment of cardiovascular risk.

The role of cardiac PET in diagnosis and prognosis of patients with ischemia with no obstructive coronary arteries (INOCA)

Chest pain, a common symptom in cardiovascular care, often leads to the investigation of obstructive coronary artery disease (CAD). However, many patients experience chest pain without obstructive CAD, termed INOCA (Ischemia with Non-Obstructive Coronary Arteries) or CMD (Coronary Microvascular Dysfunction). INOCA can be attributed to endothelial dysfunction, vascular smooth muscle dysfunction, or both, affecting about 20-30 % of patients with nonobstructive CAD. The diagnostic approach for INOCA includes both invasive and non-invasive methods, with cardiac PET (Positron Emission Tomography) playing a significant role in risk stratification and management. PET evaluates various parameters like myocardial blood flow under stress and rest, myocardial flow reserve, and myocardial ischemia. Such comprehensive assessment is essential in accurately diagnosing and managing INOCA, considering the complexity of this condition.

Coronary artery calcium score and pre-test probabilities as gatekeepers to predict and rule out perfusion defects in positron emission tomography

BACKGROUND

Little is known about the gatekeeper performance of coronary artery calcium score (CACS) before myocardial perfusion positron emission tomography (PET), compared with updated pre-test probabilities from American and European guidelines (pre-test-AHA/ACC, pre-test-ESC).

METHODS

We enrolled participants without known coronary artery disease undergoing CACS and Rubidium-82 PET. Abnormal perfusion was defined as summed stress score ≥ 4. Using Bayes' formula, pre-test probabilities and CACS were combined into post-test probabilities.

RESULTS

We included 2050 participants (54% male, mean age 64.6 years) with median CACS 62 (IQR 0-380), pre-test-ESC 17% (11-26), pre-test-AHA/ACC 27% (16-44), and abnormal perfusion in 437 participants (21%). To predict abnormal perfusion, area under the curve of CACS was 0.81, pre-test-AHA/ACC 0.68, pre-test-ESC 0.69, post-test-AHA/ACC 0.80, and post-test-ESC 0.81 (P < 0.001 for CACS vs. each pre-test, and each post-test vs. pre-test). CACS = 0 had 97% negative predictive value (NPV), pre-test-AHA/ACC ≤ 5% 100%, pre-test-ESC ≤ 5% 98%, post-test-AHA/ACC ≤ 5% 98%, and post-test-ESC ≤ 5% 96%. Among participants, 26% had CACS = 0, 2% pre-test-AHA/ACC ≤ 5%, 7% pre-test-ESC ≤ 5%, 23% post-test-AHA/ACC ≤ 5%, and 33% post-test-ESC ≤ 5% (all P < 0.001).

CONCLUSIONS

CACS and post-test probabilities are excellent predictors of abnormal perfusion and can rule it out with very high NPV in a substantial proportion of participants. CACS and post-test probabilities may be used as gatekeepers before advanced imaging. Coronary artery calcium score (CACS) predicted abnormal perfusion (SSS ≥ 4) in myocardial positron emission tomography (PET) better than pre-test probabilities of coronary artery disease (CAD), while pre-test-AHA/ACC and pre-test-ESC performed similarly (left). Using Bayes' formula, pre-test-AHA/ACC or pre-test-ESC were combined with CACS into post-test probabilities (middle). This calculation reclassified a substantial proportion of participants to low probability of CAD (0-5%), not needing further imaging, as shown for AHA/ACC probabilities (2% with pre-test-AHA/ACC to 23% with post-test-AHA/ACC, P < 0.001, right). Very few participants with abnormal perfusion were classified under pre-test or post-test probabilities 0-5%, or under CACS 0. AUC: area under the curve. Pre-test-AHA/ACC: Pre-test probability of the American Heart Association/American College of Cardiology. Post-test-AHA/ACC: Post-test probability combining pre-test-AHA/ACC and CACS. Pre-test-ESC: Pre-test probability of the European Society of Cardiology. SSS: Summed stress score.

Combined evaluation of CAC score and myocardial perfusion imaging in patients at risk of cardiovascular disease: where are we and what do the data say

Advances in the prevention and treatment of cardiovascular disease (CVD) over the last decades have led to a marked reduction in mortality for CVD. Nevertheless, atherosclerosis leading to coronary artery disease and stroke remains one of the most common causes of death in the world. The usefulness of imaging tests in the early identification of disease led to identify subjects at major risk of poor outcomes, suggesting risk factor modification. The aim of this article is to analyze the state of art of combined imaging in patients at risk of CVD referred to MPI evaluation, to highlight the present and potential features able to provide incremental prognostic information to help clinicians in patient management and to reduce adverse events.

Coronary microvascular health in symptomatic patients with prior COVID-19 infection: an updated analysis

AIMS

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with endothelial dysfunction. We aimed to determine the effects of prior coronavirus disease 2019 (COVID-19) on the coronary microvasculature accounting for time from COVID-19, disease severity, SARS-CoV-2 variants, and in subgroups of patients with diabetes and those with no known coronary artery disease.

METHODS AND RESULTS

Cases consisted of patients with previous COVID-19 who had clinically indicated positron emission tomography (PET) imaging and were matched 1:3 on clinical and cardiovascular risk factors to controls having no prior infection. Myocardial flow reserve (MFR) was calculated as the ratio of stress to rest myocardial blood flow (MBF) in mL/min/g of the left ventricle. Comparisons between cases and controls were made for the odds and prevalence of impaired MFR (MFR < 2). We included 271 cases matched to 815 controls (mean ± SD age 65 ± 12 years, 52% men). The median (inter-quartile range) number of days between COVID-19 infection and PET imaging was 174 (58-338) days. Patients with prior COVID-19 had a statistically significant higher odds of MFR <2 (adjusted odds ratio 3.1, 95% confidence interval 2.8-4.25 P < 0.001). Results were similar in clinically meaningful subgroups. The proportion of cases with MFR <2 peaked 6-9 months from imaging with a statistically non-significant downtrend afterwards and was comparable across SARS-CoV-2 variants but increased with increasing severity of infection.

CONCLUSION

The prevalence of impaired MFR is similar by duration of time from infection up to 1 year and SARS-CoV-2 variants, but significantly differs by severity of infection.

Myocardial Flow Reserve, an Independent Prognostic Marker of All-Cause Mortality Assessed by 82Rb PET Myocardial Perfusion Imaging: A Danish Multicenter Study

BACKGROUND

Rubidium-82 positron emission tomography (82Rb PET) myocardial perfusion imaging is used in clinical practice to quantify regional perfusion defects. Additionally, 82Rb PET provides a measure of absolute myocardial flow reserve (MFR), describing the vasculature state of health. We assessed whether 82Rb PET-derived MFR is associated with all-cause mortality independently of the extent of perfusion defects.

METHODS

We conducted a multicenter clinical registry-based study of patients undergoing 82Rb PET myocardial perfusion imaging on suspicion of chronic coronary syndromes. Patients were followed up in national registries for the primary outcome of all-cause mortality. Global MFR ≤2 was considered reduced.

RESULTS

Among 7169 patients studied, 38.1% were women, the median age was 69 (IQR, 61-76) years, and 39.0% had MFR ≤2. A total of 667 (9.3%) patients died during a median follow-up of 3.1 (IQR, 2.6-4.0) years, more in patients with MFR ≤2 versus MFR >2 (15.7% versus 5.2%; P<0.001). MFR ≤2 was associated with all-cause mortality across subgroups defined by the extent of perfusion defects (all P<0.05). In a Cox survival regression model adjusting for sex, age, comorbidities, kidney function, left ventricular ejection fraction, and perfusion defects, MFR ≤2 was a robust predictor of mortality with a hazard ratio of 1.62 (95% CI, 1.31-2.02; P<0.001). Among patients with no reversible perfusion defects (n=3101), MFR ≤2 remained strongly associated with mortality (hazard ratio, 1.86 [95% CI, 1.26-2.73]; P<0.01). The prognostic value of impaired MFR was similar for cardiac and noncardiac death.

CONCLUSIONS

MFR ≤2 predicts all-cause mortality independently of the extent of perfusion defects. Our results support the inclusion of MFR when assessing the prognosis of patients suspected of chronic coronary syndromes.

The Role of Cardiac PET in Diagnosis and Prognosis of Ischemic Heart Disease: Optimal Modality Across Different Patient Populations

PURPOSE OF REVIEW

Despite single-photon emission computerized tomography (SPECT) being the most used nuclear imaging technique for diagnosis of coronary artery disease (CAD), many now consider positron emission tomography (PET) as a superior modality. This review will focus on the advances of cardiac PET in recent years and its advantages compared to SPECT in diagnosis and prognosis of CAD.

RECENT FINDINGS

PET's higher resolution and enhanced diagnostic accuracy, as well as lower radiation exposure, all help explain the rationale for its wider spread and use. PET also allows for measurement of myocardial blood flow (MBF) and myocardial flow reserve (MFR), which aids in several different clinical scenarios, such as diagnosing multivessel disease or identifying non-responders. PET has also been shown to be useful in diagnosing CAD in various specific populations, such as patients with prior COVID-19 infection, cardiac transplant, and other comorbidities.

Incremental prognostic value of positron emission tomography derived left ventricular mass

BACKGROUND

Left ventricular hypertrophy has been shown to be an independent predictor of outcomes in patients with coronary artery disease (CAD). We aimed to determine the incremental prognostic value of positron emission tomography (PET) derived left ventricular mass (LVM) to clinical variables and myocardial flow reserve (MFR).

METHODS

We included consecutive patients who had clinically indicated PET myocardial perfusion imaging for suspected or established CAD. Patients were followed from the date of PET imaging for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention/coronary artery bypass grafting 90 days after imaging).

RESULTS

A total of 2357 patients underwent PET MPI during the study period (47% female, mean age 66 ± 12 years, 87% hypertensive, 47% diabetic, 79% dyslipidemia). After a mean follow-up of 11.6 ± 6.6 months, 141 patients (6.0%, 5.1 per 1000 person-year) experienced MACE (86 D/24 MI/39 PCI/9 CABG). In nested multivariable Cox models, LVM was not independently associated with outcomes (HR 1.00, P = .157) and had no incremental prognostic value (C index: 0.75, P = .571) over MFR and clinical variables.

CONCLUSION

Our analysis shows that LVM provides no independent and incremental prognostic value over MFR and clinical variables.

Direct Risk Assessment From Myocardial Perfusion Imaging Using Explainable Deep Learning

BACKGROUND

Myocardial perfusion imaging (MPI) is frequently used to provide risk stratification, but methods to improve the accuracy of these predictions are needed.

OBJECTIVES

The authors developed an explainable deep learning (DL) model (HARD MACE [major adverse cardiac events]-DL) for the prediction of death or nonfatal myocardial infarction (MI) and validated its performance in large internal and external testing groups.

METHODS

Patients undergoing single-photon emission computed tomography MPI were included, with 20,401 patients in the training and internal testing group (5 sites) and 9,019 in the external testing group (2 different sites). HARD MACE-DL uses myocardial perfusion, motion, thickening, and phase polar maps combined with age, sex, and cardiac volumes. The primary outcome was all-cause mortality or nonfatal MI. Prognostic accuracy was evaluated using area under the receiver-operating characteristic curve (AUC).

RESULTS

During internal testing, patients with normal perfusion and elevated HARD MACE-DL risk were at higher risk than patients with abnormal perfusion and low HARD MACE-DL risk (annualized event rate, 2.9% vs 1.2%; P < 0.001). Patients in the highest quartile of HARD MACE-DL score had an annual rate of death or MI (4.8%) 10-fold higher than patients in the lowest quartile (0.48% per year). In external testing, the AUC for HARD MACE-DL (0.73; 95% CI: 0.71-0.75) was higher than a logistic regression model (AUC: 0.70), stress total perfusion deficit (TPD) (AUC: 0.65), and ischemic TPD (AUC: 0.63; all P < 0.01). Calibration, a measure of how well predicted risk matches actual risk, was excellent in both groups (Brier score, 0.079 for internal and 0.070 for external).

CONCLUSIONS

The DL model predicts death or MI directly from MPI, by estimating patient-level risk with good calibration and improved accuracy compared with traditional quantitative approaches. The model incorporates mechanisms to explain to the physician which image regions contribute to the adverse event prediction.

Incremental prognostic value of digital positron emission tomography derived myocardial flow reserve: A prospective cohort study

BACKGROUND

Positron Emission Tomography (PET) Myocardial Perfusion Imaging (MPI) is a robust diagnostic and prognostic test in patients with suspected or known coronary artery disease (CAD). We aimed to assess the incremental prognostic value of myocardial flow reserve (MFR) using the latest generation of digital PET scanners.

METHODS

Consecutive patients with clinically indicated PET MPI for suspected or known CAD were included. Myocardial blood flow (MBF) in ml/min/g was obtained from dynamic images at rest and peak hyperemia, and the myocardial flow reserve (MFR) was calculated as the ratio of stress to rest MBF. Patients were followed from the date of PET imaging for the occurrence of the primary outcome (composite of all-cause death, myocardial infarction, and Percutaneous Coronary Intervention or Coronary Artery Bypass Graft occurring >90 days after imaging). Nested multivariable Cox regression models were used to assess the incremental prognostic role of MFR over traditional risk factors and PET relative perfusion parameters.

RESULTS

The final cohort consisted of 3534 patients (mean age 67 ± 12 years, 48% female, 67% Caucasian, 53% obese, 55% hypertension, 32% diabetes, 42% dyslipidemia). During a median follow-up of 8.5 (3.0-15.4) months, 229 patients (6.5%, 6.4 per 1000 person-years) experienced the primary outcome. In nested multivariable Cox models, impaired MFR (MFR < 2) was significantly associated with the primary outcome (HR 2.9, 95% CI 2.0-4.1, p < 0.001) and significantly improved discrimination (Harrell's C 0.77, p = 0.002).

CONCLUSION

MFR derived from digital PET scanners has an independent and incremental prognostic role in patients with suspected or known CAD.

Insights into Myocardial Perfusion PET Imaging: the Coronary Flow Capacity

Purpose of Review

The present work summarizes the clinical relevance of coronary flow capacity (CFC) with an eye on future perspectives.

Recent findings

CFC concept has been recently introduced providing a comprehensive framework for coronary physiology evaluation.

Summary

It has been widely demonstrated that coronary artery disease (CAD) is a complex disease with a multifactorial etiology resulting from different pathogenic mechanisms. Cardiac positron emission tomography (PET) currently represents the gold standard for CAD assessment, providing absolute myocardial perfusion data including coronary flow reserve (CFR), calculated as the ratio of hyperemic to rest absolute myocardial blood flows. CFC can be obtained from dynamic PET images by plotting the primary stress perfusion data and CFR values for each pixel on a graph of predefined exact ranges. The routine evaluation of this parameter may add diagnostic and prognostic value to clinical and conventional imaging data.

Added prognostic value of plaque burden to computed tomography angiography and myocardial perfusion imaging

BACKGROUND AND AIMS

Cardiac computed tomographic angiography (CCTA) - derived measures of coronary artery disease (CAD) burden have been shown to independently predict incident cardiovascular events. We aimed to compare the added prognostic value of plaque burden to CCTA anatomic assessment and single photon emission computed tomography (SPECT) physiologic assessment in a cohort with high prevalence of risk factors undergoing both tests.

METHODS

Consecutive patients who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected CAD were included. Stenosis severity and segment involvement score (SIS - number of segments with plaque irrespective of stenosis) were determined from CCTA, and presence of ischemia was determined from SPECT. Patients were followed for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention or coronary artery bypass grafting 90-days after imaging test.) RESULTS: A total of 956 patients were included (mean age 61.1 ± 14.2 years, 54% men, 89% hypertension, 81% diabetes, 84% dyslipidemia). Obstructive stenosis (left main ≥50%, all other coronary segments ≥70%) and ischemia were observed in a similar number of patients (14%). In multivariable Cox regression models, SIS significantly predicted outcomes and improved risk discrimination in models with CCTA obstructive stenosis (HR 1.15, p ≤ 0.001; Harrel's C 0.74, p = 0.008) and SPECT ischemia (HR 1.14, p < 0.001; Harrel's C 0.76, p = 0.019).

CONCLUSIONS

Our results suggest that in patients with suspected CAD and a high prevalence of risk-factors, plaque burden adds incremental prognostic value over established CCTA and SPECT measures to predict incident cardiovascular outcomes.