Ischemia Mediated Contractile Dysfunction Modulates Functional Mitral Regurgitation - Multiparametric Strain and Tissue Characterization Data from the Society of Cardiovascular Magnetic Resonance (scmr) Registry

Introduction: LV ischemia has been linked to functional mitral regurgitation (FMR) but ischemia is present many pts without FMR. CMR concomitantly assesses MR, ischemia and LV function but has not been used to test factors modifying impact of ischemia on FMR. Methods: Vasodilator stress CMR was performed in CAD pts in a multicenter registry, in whom advanced (≥moderate) FMR was confirmed by core lab. LV ischemia was categorized by subpapillary involvement (subtending mitral apparatus). To test mechanism by which ischemia impacts FMR, LV strain was measured in pts with ischemia and <5% LV infarct, with and without (1:2) FMR, matched for ischemia extent/distribution. Followup was done for mortality. Results: 2639 pts were studied; 7% had advanced FMR. While FMR pts had more ischemia in subpapillary (21.8 ± 28.3 vs 13.4 ± 21.9%) and nonpapillary (19.2 ± 25.5 vs 13.0 ± 22.2%) regions (p<0.001), multivariate analysis showed only subpapillary ischemia (OR 1.13 per 5% LV [1.05, 1.21] p=0.001) to be associated with FMR (nonpapillary p=NS). Wall motion scores in ischemic subpapillary segments were higher in pts with FMR (1.7±0.9 vs 0.8±0.9, p<0.001) paralleling strain subgroup data (n=114): FMR prevalence increased stepwise with impaired radial and circumferential strain ( Figure ). Adverse mitral remodeling associated with impaired strain; mitral tenting area (OR -0.01 per % [-0.02, -0.004] p<0.01) and papillary fractional shortening (OR 0.36 per % [0.26, 0.47] p<0.001) each associated with subpapillary radial strain controlling for nonpapillary strain (p=NS). On follow up (median 4.7 [2.2, 7.7] yr), FMR, age, subpapillary ischemia and infarction each independently predicted death (p<0.001): When categorized as dysfunctional or non-dysfunctional, only ischemic/dysfunctional myocardium (HR 1.15 per 5% LV [1.05, 1.14] p<0.001) associated with death. Conclusions: Ischemia mediated LV dysfunction on multiparametric CMR modulates likelihood of FMR and adverse prognosis.