Incremental Prognostic Value of Cardiac MRI ‐Based Right‐to‐Left Ventricular Blood Pool T2 Ratio in Patients With Dilated Cardiomyopathy

BACKGROUND: Blood T2 is sensitive to blood oxygenation level, and right ventricular (RV) oxygenation abnormalities may be detected by the relative difference between T2 values of the left ventricular (LV) and RV blood pools. PURPOSE: To investigate the prognostic value of right-to-left ventricular blood pool T2 ratio (RV/LV T2 ratio) in patients with dilated cardiomyopathy (DCM). STUDY TYPE: Retrospective. POPULATION: Three hundred and eleven patients with DCM (mean age: 52 ± 14.5 years; 72% male) and 30 age- and sex-matched healthy controls. FIELD STRENGTH/SEQUENCE: 1.5 or 3.0 T, steady-state free precession cine sequence, T2-prepared fast low-angle shot T2 mapping sequence, and phase-sensitive inversion recovery late gadolinium enhancement (LGE) sequence. ASSESSMENT: Clinical characteristics, conventional cardiac MRI parameters (ventricular volumes, function, mass), LGE extent, native myocardial T2, LV and RV strain, and RV/LV T2 ratio were assessed. Patients were followed up for a median duration of 34 months (interquartile range 21-45 months). The primary outcome, major adverse cardiac events (MACE), includes all-cause mortality, heart failure-related hospitalization, heart transplantation, or aborted sudden cardiac death. The incremental prognostic value of RV/LV T2 ratio for MACE was assessed beyond traditional risk factors. STATISTICAL TESTS: The prognostic value of RV/LV T2 ratio was evaluated using multivariable Cox regression analysis and Kaplan-Meier curves. Incremental prognostic value was evaluated using C indices and likelihood ratio tests. A p value < 0.05 was considered significant. RESULTS: One hundred and twenty-four patients experienced MACE. RV/LV T2 ratio was significantly lower in participants with MACE, and was associated with MACE in patients with DCM, irrespective of LVEF and LGE extent (above or below median value). In Cox analysis, RV/LV T2 ratio was independently associated with MACE (hazard ratio: 1.32 per 0.1 decrease), and provided significant incremental prognostic value beyond traditional risk factors in patients with DCM. DATA CONCLUSIONS: RV/LV T2 ratio was independently associated with MACE among patients with DCM, providing incremental prognostic value when combined in a model with clinical and conventional MRI risk factors. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: 5.