Stress CMR ischemic burden and long-term mortality in left ventricular systolic dysfunction: a multicenter registry study.
BACKGROUND Stress perfusion cardiovascular magnetic resonance (CMR) integrates assessment of myocardial ischemia, scar, and function. Its incremental prognostic value in patients with left ventricular (LV) systolic dysfunction remains uncertain. METHODS We analyzed a prospective multicenter registry of consecutive patients undergoing vasodilator stress perfusion CMR at three French centers (2008-2024). Patients with CMR-derived LVEF <50% were included. The primary end point was all-cause mortality. Associations were estimated with multivariable Cox models. Incremental prognostic value of ischemia and late gadolinium enhancement (LGE) beyond clinical factors and LVEF was assessed by likelihood-ratio χ2, continuous net reclassification improvement (NRI), and integrated discrimination improvement (IDI). RESULTS Among 5,977 patients (79% men; age 66±12 years, mean LVEF 42±7%), inducible ischemia was present in 19% (mean extent 2.4±1.2 segments). Over a median follow-up of 9 years, 1,343 patients (22%) died. Ischemic segment extent was independently associated with mortality (HR per segment 1.11; 95% CI, 1.06-1.15; p<0.001). Adding ischemia and LGE to clinical factors and LVEF improved model fit and reclassification (global χ2 increased from 707 to 728; NRI 0.217; IDI 0.004; all p<0.001). Findings were consistent across LVEF subgroups (40-50% and <40%). In secondary analyses among patients with ischemia, outcomes differed by subsequent revascularization status; these findings are observational and hypothesis-generating. CONCLUSIONS In patients with LVEF <50%, ischemic burden on stress-CMR is independently associated with long-term mortality beyond clinical factors, LVEF and LGE. Integrating ischemia and scar metrics provides incremental prognostic information that may aid risk stratification using stress-CMR in LV systolic dysfunction.