Myocardial perfusion imaging and risk classification for coronary heart disease in diabetic patients. The IDIS study: a prospective, multicentre trial.

PURPOSE: To determine whether stress-rest myocardial perfusion single-photon emission (MPS) computed tomography improves coronary heart disease (CHD) risk classification in diabetic patients. METHODS: In 822 consecutive diabetic patients, risk estimates for a CHD event were categorized as 0% to <3%, 3% to <5%, and ≥5% per year using Cox proportional hazards models. Model 1 used traditional CHD risk factors and electrocardiography (ECG) stress test data and model 2 used these variables plus MPS imaging data. We calculated the net reclassification improvement (NRI) and compared the distribution of risk using model 2 vs. model 1. CHD death, myocardial infarction and unstable angina requiring coronary revascularization were the outcome measures. RESULTS: During follow-up (58 ± 11 months), 148 events occurred. Model 2 improved risk prediction compared to model 1 (NRI 0.25, 95% confidence interval, CI, 0.15-0.34; p < 0.001). Overall, 301 patients were reclassified to a higher risk category, with an event rate of 28%, and 26 to a lower risk category, with an event rate of 15%. Among patients at 3% to <5% risk, 53% were reclassified at higher risk and 25% at lower risk (NRI 0.42, 95% CI 0.07-0.76; p < 0.05). The cost per NRI was $880.80 for MPS imaging as compared to an outpatient visit with an ECG stress test. CONCLUSION: The addition of MPS imaging data to a prediction model based on traditional risk factors and ECG stress test data significantly improved CHD risk classification in patients with diabetes.

Incremental prognostic value of coronary flow reserve assessed with single-photon emission computed tomography.

BACKGROUND: We assessed the prognostic value of coronary flow reserve (CFR) estimated by single-photon emission computed tomography (SPECT) in patients with suspected myocardial ischemia. METHODS AND RESULTS: Myocardial perfusion and CFR were assessed in 106 patients using dipyridamole/rest Tc-99m sestamibi SPECT and follow-up was obtained in 103 (97%) patients. Four early revascularized patients were excluded and 99 were assigned to normal (summed stress score <3) vs abnormal myocardial perfusion and to normal (≥2.0) vs abnormal CFR. During the follow-up (5.8 ± 2.1 years), 28 patients experienced a cardiac event (cardiac death, nonfatal myocardial infarction, and late revascularization). Abnormal perfusion (P < .01) and abnormal CFR (P < .05) were independent predictors of cardiac events at Cox proportional hazard regression analysis. Also in patients with normal perfusion, abnormal CFR was associated with a higher annual event rate compared with normal CFR (5.2% vs 0.7%; P < .05). CFR data improved the prognostic power of the model including clinical and myocardial perfusion data increasing the global chi-square from 18.6 to 22.8 (P < .05). Finally, at parametric survival analysis, in patients with normal perfusion the time to achieve ≥2% risk of events was >60 months in those with normal and <12 months in those with abnormal CFR. CONCLUSIONS: Myocardial perfusion findings and CFR at SPECT imaging are both independent predictors of cardiac events. Estimated CFR provides incremental prognostic information over those obtained from clinical and myocardial perfusion data, particularly in patients with normal perfusion findings.

Effects of exercise training started within 2 weeks after acute myocardial infarction on myocardial perfusion and left ventricular function: a gated SPECT imaging study.

BACKGROUND: Several studies suggested that exercise training might improve myocardial perfusion by inducing coronary vascular adaptations or enhancing collateralization. However, these findings were obtained in patients with chronic coronary artery disease using thallium-201 myocardial perfusion scintigraphy. We evaluated whether a long-term exercise-based cardiac rehabilitation (CR) started early (9 ± 3 days) after ST elevation acute myocardial infarction (STEMI) improves myocardial perfusion and left ventricular (LV) function, evaluated by gated single-photon emission computed tomography (SPECT) imaging. DESIGN: Randomized controlled study. METHODS: Fifty patients with recent STEMI were randomized into two groups: 24 enrolled in a 6-month exercise-based CR programme (group T) and 26 discharged with generic instructions for maintaining physical activity and correct lifestyle (group C). All patients underwent cardiopulmonary exercise test and gated SPECT within 3 weeks after STEMI and at 6-month follow up. RESULTS: At follow up, group T showed a significant reduction of stress-induced ischaemia (p < 0.01) and an improvement in resting and post-stress wall motion (both p < 0.005) and resting (p < 0.05) and post-stress wall thickness (p < 0.005) score indexes. At follow up, group T showed an improvement in peak oxygen consumption (p < 0.0001), O(2) pulse (p < 0.05), and in the slope of increase in ventilation over carbon dioxide output (p < 0.001). No changes in myocardial perfusion parameters, LV function, and cardiopulmonary indexes were observed in group C at follow up. CONCLUSIONS: Six months of exercise training early after STEMI reduces stress-induced ischaemia and improves LV wall motion and thickness. Exercise-induced changes in myocardial perfusion and function were associated with the absence of unfavourable LV remodelling and with the improvement of cardiovascular functional capacity.

Prognostic value of coronary artery calcium score and coronary CT angiography in patients with intermediate risk of coronary artery disease.

The aim of this study was to compare the prognostic value of coronary calcium scoring and coronary computed tomography (CT) angiography in assessing the cardiac risk and its temporal characteristics in patients at intermediate pre-test likelihood of coronary artery disease (CAD). Cardiac CT was performed in 326 patients at intermediate (15-85%) pre-test likelihood of CAD to evaluate calcium score and presence and severity of the disease. Patients were followed-up for the occurrence of major cardiac events (cardiac death, myocardial infarction, and unstable angina requiring revascularization). During follow-up (26 ± 12 months) 34 events occurred. Calcium score, extent of CAD, and plaque extent and distribution were higher (all P < 0.001) in patients with events than in those without. No patients with calcium score of 0 had events at follow-up. Calcium score (P < 0.001), number of segments with non-calcified or mixed plaque (P < 0.05), and segments-at-risk-score (P < 0.005) were independent predictors of events. Cardiac risk was greater for all time intervals and accelerated more over time with worsening of calcium score. In presence of coronary calcium, significant CAD further increased the probability of failure for all time intervals. Therefore, patients at intermediate CAD risk without coronary calcium do not need further evaluation with longer and higher-radiation-dose protocols, while in the presence of coronary calcium CT angiography is useful to further stratify patients.