Thirteen studies were identified (n=2,113 participants) from which 268 participants met the inclusion criteria and were included in the synthesis. All studies were single-centre retrospective cohort studies and all were considered to be poor quality. Sample sizes ranged from 27 to 848 patients and from these between five and 76 patients met review criteria. Mean follow-up with echocardiography ranged from 19 days to 3.5 years postoperatively.
Of the 268 patients with preoperative functional mitral regurgitation, 164 (61%) improved, 103 remained the same (38%) and one worsened at the most recent postoperative echocardiography follow-up. Two out of four studies reported significantly poorer survival in patients with moderate to severe mitral regurgitation compared to mild and/or none.
Additional prognostic factors for survival and progression of mitral regurgitation were reported.