Undersized annuloplasty for functional mitral regurgitation: is it responsible for clinically relevant mitral stenosis during exercise?

BACKGROUND AND AIM OF THE STUDY: The study aim was to assess if an undersized mitral annuloplasty for functional mitral regurgitation (FMR) in dilated cardiomyopathy can determine a clinically relevant mitral stenosis during exercise. METHODS: Both, rest and stress echocardiography were performed in 12 patients submitted to an undersized ring annuloplasty for FMR in dilated cardiomyopathy. The mean ring size was 27 +/- 1.3 mm. All patients were in NYHA functional classes I-II, were in stable sinus rhythm, and without significant residual mitral regurgitation (grade < or = 2/4). RESULTS: At peak exercise (mean 81 +/- 12 W), the main cardiac performance indices were significantly improved, including systolic blood pressure (121 +/- 5.6 versus 169 +/- 14 mmHg, p < 0.001), stroke volume (63 +/- 15 versus 77 +/- 14 ml, p < 0.001), left ventricular ejection fraction (43 +/- 9% versus 47 +/- 9%, p = 0.001), and systolic right ventricular function (pulsed tissue Doppler index peak systolic velocity: 8.6 +/- 1.7 versus 11.1 +/- 3.2 cm/s, p = 0.004). A mild increase in planimetric mitral valve area was observed at peak exercise (2.12 +/- 0.4 versus 2.17 +/- 0.3 cm2, p = 0.05). Although the transmitral mean gradient was increased from 3.2 +/- 1.2 to 6.3 +/- 2.3 mmHg (p < 0.0001), the systolic pulmonary artery pressure did not change significantly (27 +/- 2.8 versus 30.1 +/- 6.4 mmHg, p = 0.3), thus revealing a preserved cardiac adaptation to exercise. CONCLUSION: In these preliminary data, postoperative clinically relevant mitral stenosis was not observed in patients submitted to mitral repair for FMR. Stress echocardiography represents a valuable tool to assess an appropriate cardiac response to exercise and to detect a significant exercise-induced pulmonary hypertension after undersized annuloplasty ring surgery.