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

Abstract

BackgroundWe evaluated the warranty period of a normal stress myocardial perfusion single-photon emission computed tomography (MPS) in hypertensive patients. Methods and ResultsA 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. ConclusionsIn 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.