Stress CMR Perfusion Imaging in the Medicare-Eligible Population: Insights From the SPINS Study

Abstract

Background: Patients aged ≥65 years account for a disproportionately large portion of cardiovascular (CV) events and pose a challenge for noninvasive detection of coronary artery disease. Objectives: This study sought to determine the prognostic value of stress cardiac magnetic resonance (CMR) in a Medicare-eligible group of patients in a multicenter setting in the United States. Methods: From a multicenter U.S. registry, the study identified patients aged ≥65 years who were referred for stress CMR for evaluation of myocardial inducible ischemia. The primary outcome was defined as CV death or nonfatal myocardial infarction, whereas the secondary outcome was defined as any primary outcome, hospitalization for unstable angina, hospitalization for congestive heart failure, and unplanned late coronary artery bypass grafting. The associations of CMR findings with CV outcomes adjusted to clinical risk markers and health care cost spending were determined. Results: Among 1,780 patients (aged 73 ± 5.7 years; 46% female), study investigators observed 144 primary events and 323 secondary events, over a median follow-up of 4.8 years. The presence of inducible ischemia and late gadolinium enhancement (LGE) was associated with incrementally higher event rates. Patients with neither inducible ischemia nor LGE experienced a <1% annualized rate of primary outcome. In a multivariable model adjusted for CV risk factors, inducible ischemia and LGE maintained an independent association with primary (HR: 2.80 [95% CI: 1.93-4.05]; P < 0.001; and HR: 1.85 [95% CI: 1.21-2.82]; P = 0.004, respectively) and secondary (HR: 2.46 [95% CI: 1.90-3.19]; P < 0.001; and HR: 1.72 [95% CI: 1.30-2.27]; P < 0.001, respectively) outcomes. Rates of revascularization, as well as downstream costs for patients without CMR-detected inducible ischemia, remained low throughout the follow-up period. Conclusions: In a multicenter cohort of Medicare-eligible older patients, stress CMR was effective in providing risk stratification. (Stress CMR Perfusion Imaging in the United States [SPINS] study; NCT03192891)