Incremental Value of Right Ventricular Free-Wall Strain in Ventricular Functional Mitral Regurgitation: Insights from a Multicenter Study.

BACKGROUND

Ventricular functional mitral regurgitation (VFMR) is a heterogeneous disease with widely variable outcomes, yet current risk stratification relies predominantly on left ventricular (LV) indices. This study aims to evaluate the incremental 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 multicenter retrospective cohort included consecutive patients with moderately severe or greater VFMR diagnosed between 2010 and 2022. Right ventricular free-wall longitudinal strain and apical 4-chamber LVLS (A4C-LVLS) were quantified using automated software. The primary end point 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. Incremental prognostic value was assessed using likelihood ratio tests comparing nested models.

RESULTS

Among the 487 patients included, 156 (32%) patients experienced the primary end point over a median follow-up of 2.6 (interquartle range, 0.85.9) 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 ≤ .005). Right ventricular free-wall longitudinal strain was independently associated with the primary end point on top of conventional LV indices, A4C-LVLS, and RVFAC (all P ≤ .047). Patients with A4C-LVLS < 8.7% and RVfwLS < 14% exhibited markedly worse 6-year event-free survival (48%) than those with higher biventricular strain (A4C-LVLS ≥ 8.7% and RVfwLS ≥ 14%; 72%; P < .001). Moreover, RVfwLS provided incremental prognostic value beyond A4C-LVLS, conventional LV indices, and RVFAC (all P ≤ .046).

CONCLUSIONS

Right ventricular free-wall longitudinal strain is a robust determinant of adverse outcomes beyond conventional LV indices and A4C-LVLS in VFMR. A cutoff near 14% reliably identified the highest-risk subgroup. These results might support incorporating RVfwLS into routine evaluation to improve risk stratification in VFMR.