Prognostic Value of Regadenoson Stress Perfusion CMR

Background/Objectives: Regadenoson is increasingly used as a vasodilator stress agent for perfusion cardiac magnetic resonance (CMR) imaging due to its favorable pharmacologic profile. However, its long-term prognostic value in patients with myocardial ischemia remains insufficiently established. Methods: We retrospectively analyzed all regadenoson stress-CMR studies performed at our institution between May 2017 and July 2020, including patients with follow-up longer than three months. Inducible ischemia and late gadolinium enhancement (LGE) were assessed using standardized criteria. The primary composite endpoint included cardiovascular death, non-fatal myocardial infarction, late coronary revascularization (≥3 months after CMR), or hospitalization for unstable angina. Event-free survival was analyzed with Kaplan-Meier curves, and prognostic factors were evaluated using a Fine-Gray competing-risks model. Results: Of 705 examinations, 698 were eligible, and 517 patients (78.5%) completed follow-up over a median of 1.93 years (IQR 1.37-2.79). Inducible ischemia was identified in 142 patients (27.5%). During follow-up, 38 composite events occurred. Event incidence was significantly higher in patients with ischemia (109.6 events/1000 person-years; 95% CI 75.7-158.7) than in those without (13.3 events/1000 person-years; 95% CI 7.2-24.7; RR 8.25; 95% CI 4.01-16.98; p < 0.001). In multivariable analysis, inducible ischemia independently predicted adverse outcomes (HR 4.50; 95% CI 1.86-10.9; p = 0.001), whereas LGE was not independently associated (HR 1.28; 95% CI 0.46-3.57; p = 0.63). Conclusions: Regadenoson stress-CMR provides robust medium-term risk stratification in patients with suspected or known coronary artery disease. Detection of inducible ischemia strongly predicts major cardiovascular events, underscoring its prognostic and clinical relevance.