右心室機能の僧帽弁手術後：英国ミニ僧帽弁試験からの洞察

Right ventricular (RV) function is frequently reduced following cardiac surgery, with persistent impairment associated with increased mortality. This study aimed to compare RV function following mitral valve repair via right minithoracotomy versus sternotomy.

In the UK Mini Mitral Trial, patients were randomized to mitral valve repair via right minithoracotomy (small lateral pericardial incision) or sternotomy. Prespecified secondary outcomes included assessment of cardiac function via blinded echocardiography pre-operatively, at early (12 weeks) and late (52 weeks) time points. RV function was assessed via tricuspid annular plane systolic excursion (TAPSE). RV to pulmonary artery coupling was determined by the TAPSE to systolic pulmonary artery pressure ratio.

Of 330 patients randomized, 224 had suitable echocardiographic data for analysis. Baseline demographic, clinical, and echocardiographic data were comparable between groups. Cross-clamp and bypass times were significantly longer in the minithoracotomy group. At 12 weeks, there was a significant reduction in TAPSE from baseline in both groups (TAPSE minithoracotomy -7.52mm, 95% confidence interval (CI) -8.52 - -6.53, P<0.001, versus sternotomy -8.75mm, -9.80 - -7.71, P<0.001), which recovered, however not to pre-operative levels by 52 weeks. The degree of RV impairment was significantly less in the minithoracotomy group at both early (between group difference in TAPSE 1.47mm, 95% CI 0.37 - 2.56, P=0.009) and late time points (1.37mm, 95% CI 0.29 - 2.45, P=0.013).

Despite longer cross-clamp and bypass times, mitral valve repair via minithoracotomy, was superior to sternotomy at preserving RV function (measured by TAPSE), at 12 weeks and one year.