Prediction of 9-year cardiovascular outcomes by myocardial perfusion imaging in patients with normal exercise electrocardiographic testing

Abstract

Exercise myocardial perfusion imaging (MPI) is widely used, but the long-term prognostic value of this test in patients with normal exercise electrocardiographic testing is not defined. A consecutive group of 650 patients (428 men, mean age: 56 ± 11 years) with known or suspected coronary artery disease underwent exercise electrocardiographic testing and MPI. Follow-up endpoints were mortality and major adverse cardiac events (MACE). Predictors of outcome were identified by multivariate logistic regression analysis using clinical, exercise electrocardiographic testing and single-photon emission computed tomography (SPECT) variables. A total of 324 (50%) patients had an abnormal SPECT, and 131 (20%) had completely or partially reversible perfusion defects. During a mean follow-up of 9.2 ± 2.0 years, 107 (23%) patients died, 69 (11%) had a non-fatal myocardial infarction, 90 (14%) underwent coronary artery bypass surgery, and 142 (22%) percutaneous coronary intervention. Multivariate analysis demonstrated that the summed rest score was an independent predictor of mortality [hazard ratio (HR): 1.15, 95% confidence interval (CI): (1.08-1.22], P < 0.001). The summed stress score was an independent predictor of MACE [HR: 1.09, 95% CI: (1.04-1.13), P < 0.001]. The addition of SPECT variables to clinical and exercise electrocardiographic testing data provided incremental prognostic information for the prediction of mortality and MACE (both P < 0.001). Approximately 20% of patients with known or suspected coronary artery disease and normal exercise electrocardiographic testing have completely or partially reversible myocardial perfusion defects. MPI provides additional information for the prediction of 9-year cardiovascular outcomes in these patients.