Abstract 19425: Stress Perfusion Cardiac Magnetic Resonance Predicts Risk of Cardiac Events in Patients with Established Coronary Artery Disease

Abstract

BACKGROUND: Current prognostic risk assessment has limited sensitivity for identification of patients at high risk for cardiac events with established CAD. We evaluated the prognostic value of stress cardiac magnetic resonance (CMR) imaging to reclassify risk in patients with established CAD.

METHODS: We performed clinically indicated stress CMR imaging in 815 patients, with follow-up for cardiac death (CD) or acute myocardial infarction (AMI; primary outcome) over a median 1.9 years. Univariate and multivariate Cox regression models were used to determine clinical and imaging characteristics associated with risk. Annual event rates were calculated and stratified by presence and absence of prior CAD. Net reclassification improvement and ROC analysis were used for the addition of inducible ischemia by CMR beyond a best-overall clinical multivariate model of risk for discrimination and reclassification.

RESULTS: Of the 815 patients referred for stress CMR, 13 failed to complete CMR (2%), and 97% had interpretable image quality. Inducible ischemia (ISCH) strongly independently predicted primary outcome in CAD patients (HR = 8.17, 95% CI 2.9-23.1, p = 0.0001). No ISCH was associated significantly improved event-free survival in patients with and without CAD (p<0.001) and a <1% annual rate of CD, with lower annual rates of CD/AMI in patients with and without CAD. ISCH improved risk discrimination over a best-overall clinical risk model (p<0.0001). Addition of ISCH to the best-overall clinical model resulted in a net reclassification improvement of 0.229 (95% 0.063-0.391, p<0.05).

CONCLUSIONS: Inducible ischemia by stress CMR is a powerful, independent prognostic marker in patients with symptomatic, established CAD. A negative stress CMR is associated with a <1% rate of CD, and reclassifies risk of future cardiac events in patients otherwise considered at moderate or high risk by clinical assessment.