Incremental value of right ventricular free-wall strain in ventricular functional mitral regurgitation: insights from a multicentre study

Background Ventricular functional mitral regurgitation (VFMR) is a heterogeneous condition with widely variable outcomes, yet current risk stratification relies predominantly on left ventricular (LV) indices. Purpose To evaluate the added value of right ventricular free-wall longitudinal strain (RVfwLS) beyond conventional LV parameters and LV longitudinal strain (LVLS) in an unselected VFMR population. Methods This multicentre retrospective cohort included consecutive patients with ≥moderately-severe VFMR diagnosed between 2010 and 2022. RVfwLS and apical four-chamber LVLS (A4C-LVLS) were quantified using automated software. The primary endpoint was cardiovascular death or death equivalent (LV assist device implantation or heart transplantation) during the longest available follow-up. Optimal cutoff for RVfwLS was derived from regression tree analysis and maximal selective rank statistics. Results Among 608 patients included, 201 patients (33%) experienced the primary endpoint over a median follow-up of 2.2 (IQR 0.7–5.7) years. Compared with event-free patients, those with events had larger LV volumes, but lower LV ejection fraction, A4C-LVLS, RV fractional area change (RVFAC), and RVfwLS (all P ≤0.031). Older age, male sex, and RVfwLS were independently associated with the primary endpoint on top of conventional LV indices, A4C-LVLS, and RVFAC (all P ≤0.046). Patients with concomitant A4C-LVLS <8.7% and RVfwLS <14% exhibited markedly worse 6-year event-free survival (48%) compared with those with preserved biventricular strain (A4C-LVLS ≥8.7% and RVfwLS ≥14%; 72%; P <0.001)(Figure 1). Moreover, RVfwLS provided incremental prognostic value beyond A4C-LVLS, conventional LV indices, and RVFAC (all P ≤0.046; Figure 2). Conclusions RVfwLS is a robust determinant for adverse outcomes beyond conventional LV indices and A4C-LVLS in VFMR. A cutoff near 14% reliably identified the highest-risk subgroup. These results may support incorporating RVfwLS into routine evaluation and staging to improve risk stratification.Figure 1Figure 2