Warranty period of normal stress myocardial perfusion imaging in hypertensive patients: A parametric survival analysis

Background We evaluated the warranty period of a normal stress myocardial perfusion single-photon emission computed tomography (MPS) in hypertensive patients. Methods and Results A total of 471 consecutive hypertensive patients with suspected coronary artery disease and normal perfusion at stress MPS were followed for a mean of 76 +/- 21 months. Endpoint events were cardiac death or nonfatal myocardial infarction. With Cox analysis, age (hazard ratio 1.1, P < .005) and stress test type (hazard ratio 2.7, P < .005) were independent predictors of events. With parametric Weibull analysis, patients <= 60 years old undergoing exercise stress test remained at low risk for the entire length of follow-up, while the highest probability of events and the major risk acceleration were observed in those > 60 years old who underwent pharmacologic stress test. In patients undergoing exercise test, peak systolic blood pressure (BP; hazard ratio 1.1, P < .005) emerged as predictor of events, and only subjects with peak systolic BP < 160 mmHg remained at low risk for the entire length of follow-up. In contrast, for patients with peak systolic BP >= 180 mmHg, the time to achieve a cumulative cardiac risk level of 3% was 18 months. Conclusions In hypertensive patients, the warranty period of a normal stress MPS varies according to stress type and peak systolic BP. A normal stress MPS can be considered reassuring in subjects <= 60 years old who performed exercise stress test and a peak systolic BP < 160 mmHg.