Direct comparison of echocardiography speckle tracking and cardiac magnetic resonance feature tracking for quantification of right ventricular strain: a prospective intermodality study in functional mitral regurgitation

BACKGROUND: Functional mitral regurgitation (FMR) is a known risk factor for right ventricular dysfunction (RV(DYS)). RV global longitudinal strain (GLS) is an emerging index of RV function; however, the magnitude of agreement between RV GLS by echocardiography (echo) and cardiac magnetic resonance (CMR) and the relative utility of each modality for both the diagnosis of RV(DYS) and prognostication of all-cause mortality and heart failure hospitalization remain unknown. RESULTS: 32% of patients had RV(DYS) (EF < 50%) on CMR, among whom there was more advanced NYHA class and lower LV and RV ejection fraction (all p < 0.05). RV GLS was impaired in patients with RV(DYS) whether quantified via STE or FT-CMR, with strong correlation between modalities (r = 0.81). Both STE and FT-CMR derived GLS yielded excellent detection of RV(DYS) (AUC 0.94 for both), paralleling similar performance for free wall strain by both modalities (FT-CMR AUC 0.94, STE AUC 0.92) with lower accuracy demonstrated by STE derived septal strain (STE AUC 0.78 and FT-CMR AUC 0.92). RV S’ and TAPSE showed lower diagnostic accuracy (RV S’ AUC 0.77 and TAPSE AUC 0.81). During median follow up of 51 months (IQR 42, 60 months), all-cause mortality or HF hospitalization occurred in 25% (n = 25). Both STE and FT-CMR derived RV GLS stratified risk for adverse prognosis (STE p = 0.007, FT-CMR p = 0.005) whereas conventional RV indices, TAPSE and RV S’, did not (TAPSE p = 0.30, S’ p = 0.69). CONCLUSION: RV GLS is a robust marker of RV(DYS) irrespective of modality which provides incremental diagnostic value and improves risk stratification for event free survival beyond conventional RV indices.