Stable Coronary Artery Disease: Prognostic Value of Myocardial Perfusion SPECT in Relation to Coronary Calcium Scoring—Long-term Follow-up

Abstract

To evaluate the incremental prognostic value of coronary artery calcification (CAC) scoring over single photon emission computed tomographic (SPECT) myocardial perfusion imaging in long-term prognosis and survival of patients with stable coronary artery disease (CAD). All patients provided written informed consent to undergo CAC scoring according to a protocol that was approved by the local clinical institutional review board. Over a median follow-up time of 5.4 years, 260 patients with stable CAD were followed up for severe cardiac events (cardiac death or nonfatal myocardial infarction). CAC scanning and SPECT myocardial perfusion imaging were performed at enrollment. Patients were stratified on the basis of well-established cutoff points for CAC score, summed stress score (SSS), and summed rest score (SRS). Kaplan-Meier survival curves and the Cox proportional hazards model were used. CAC score and SRS were identified as the only independent predictors of event-free survival. Patients with perfusion abnormalities at rest (SRS > or = 2), a CAC score greater than 400, or severe perfusion abnormalities under stress (SSS > or = 13) were identified as having significantly increased risk for subsequent severe cardiac events (P = .023, .0095, and .007, respectively). In addition, a CAC score greater than 400 offered incremental prognostic value over the scintigraphic scores alone (P = .028 with an SSS > 8; P = .008 with an SRS > or = 2). CAC score and SRS were identified as independent predictors of severe cardiac events during long-term follow-up of patients with known CAD. CAC scores imparted superior risk stratification information as compared with SPECT myocardial perfusion imaging results alone.