Impact of residual mitral valve regurgitation following septal myectomy for obstructive hypertrophic cardiomyopathy.

OBJECTIVE

To evaluate the impact of residual mitral valve (MV) regurgitation (MR) in patients with obstructive hypertrophic cardiomyopathy immediately after myectomy on late survival and the risk of MV reintervention.

METHODS

From October 2001 to February 2024, 3061 patients with hypertrophic cardiomyopathy and dynamic left ventricular outflow tract obstruction underwent septal myectomy. A 1:1 propensity score matching was performed between patients with mild or trivial/no residual MR immediately after cardiopulmonary bypass and patients with moderate or greater residual MR. Long-term survival, MR progression, and the incidence of MV reintervention were analyzed.

RESULTS

Postbypass moderate or greater residual MR was present in 398 patients (13.9%). Matching yielded 398 pairs, with no differences in age (62.1 years vs 61.9 years, P = .397), nor in median peak left ventricular outflow tract gradient on predismissal echocardiography (3 [0-9] mm Hg vs 3 [0-10] mm Hg, P = .585). Late incidence of moderate-severe or greater MR was greater in those with residual MR (15 years: 48.0% vs 11.9%, P = .002), and the incidence of subsequent MV intervention at 15 years was 3-fold greater in those with intraoperative residual MR (14.0% vs 3.9%, P = .007). However, the overall survival of the 2 groups was similar (P = .48).

CONCLUSIONS

Residual MR after septal myectomy is not associated with early or late mortality. However, beyond 5 years' postoperatively, patients with moderate or greater residual MR experience accelerated rates of recurrent MR and require MV reintervention. Residual MR may be attributable to unrecognized mild intrinsic MV disease that progresses late postoperatively.