Effect of mitral valve surgery on exercise capacity, ventricular ejection fraction and neurohormonal activation in patients with severe mitral regurgitation

OBJECTIVES The purpose of this study was to prospectively investigate the effects of surgical correction of mitral regurgitation (MR) on exercise performance, cardiac function and neurohormonal activation. BACKGROUND Little is known about the effect of surgical correction of MR on functional status or on neurohormonal activation. METHODS Cardiopulmonary exercise test, radionuclide angiography and blood samples for assessment of neurohormonal status were obtained in 40 patients with nonischemic MR before and within one year (216 ± 80 days) after surgery. Twenty-four patients underwent mitral valve repair (MVr), and 16 underwent valve replacement (VR) with anterior chordal transection. RESULTS Despite an improvement in New York Heart Association functional class, exercise performance did not change (peak oxygen consumption: 19.3 ± 6.1 to 18.5 ± 5.6 ml/kg/min, percentage of maximal predicted oxygen consumption: 79.5 ± 18.2% to 76.8 ± 16.9%). After surgery, left ventricular (LV) ejection fraction (EF) decreased (64.2 ± 10.3% to 59.9 ± 11.4%, P = 0.003) while right ventricular (RV) EF increased (41.4 ± 9.6% to 44.7 ± 9.5%, P = 0.03). Left ventricular EF did not change after MVr (64.3 ± 11.5% to 61.5 ± 12.2%), but RVEF improved (40.4 ± 9.2% to 46.0 ± 10.0%, P = 0.02). In contrast, VR was associated with an impairment of LV function in the apicolateral area and a decrease in LVEF (64.1 ± 8.5% to 57.4 ± 10.0%, P = 0.01), whereas RVEF did not change (42.9 ± 10.3% to 42.8 ± 8.6%). Moreover, there was only a slight decrease in neurohormonal activation after surgery. CONCLUSIONS Despite an improvement in symptomatic status, exercise performance was not improved seven months after either MVr or VR for MR, and neurohormonal activation persisted. Compared with MVr, VR resulted in a significant impairment of cardiac function in this study.