Does stringent restrictive annuloplasty for functional mitral regurgitation cause functional mitral stenosis and pulmonary hypertension?

BACKGROUND: It remains controversial whether restrictive mitral annuloplasty (RMA) for functional mitral regurgitation (MR) can induce functional mitral stenosis (MS) that may cause postoperative residual pulmonary hypertension (PH). METHODS AND
RESULTS: One hundred eight patients with left ventricular (LV) dysfunction and severe MR underwent RMA with stringent downsizing of the mitral annulus. Systolic pulmonary artery pressure (PAP) and mitral valve performance variables were determined by Doppler echocardiography prospectively and 1 month after RMA. Fifty-eight patients underwent postoperative hemodynamic measurements. Postoperative echocardiography showed a mean pressure half-time of 92 ± 14 ms, a transmitral mean gradient of 2.9 ± 1.1 mm Hg, and a mitral valve effective orifice area of 2.4 ± 0.4 cm(2), consistent with functional MS. Doppler-derived systolic PAP was 32 ± 8 mm Hg, which correlated weakly with the transmitral mean gradient (ρ=0.23, P=0.02). Postoperative cardiac catheterization also showed significant improvements in LV volume and systolic function, pulmonary capillary wedge pressure, cardiac index, and systolic PAP; the latter was associated with LV end-diastolic pressure [standardized partial regression coefficient (SPRC)=0.51], pulmonary vascular resistance (SPRC=0.47), cardiac index (SPRC=0.37), and transmitral pressure gradient (SPRC=0.20). In a multivariate Cox proportional hazard model, postoperative PH (systolic PAP >40 mm Hg), but not mitral valve performance variables, was strongly associated with adverse cardiac events.
CONCLUSIONS: RMA for functional MR resulted in varying degrees of functional MS. However, our data were more consistent with the residual PH being caused by LV dysfunction and pulmonary vascular disease than by the functional MS. The residual PH, not functional MS, was the major predictor of post-RMA adverse cardiac events.