Determinants of left ventricular dysfunction after repair of chronic asymptomatic mitral regurgitation

Background: The evidence supporting early surgical intervention in patients with chronic asymptomatic mitral regurgitation (MR) is steadily accumulating. Although left ventricular (LV) enlargement and preoperative pulmonary hypertension are considered when deciding on surgical intervention, the threshold above which these factors influence clinical outcomes remains poorly defined.

Methods: One-hundred fifty asymptomatic patients of aged 59.3 ± 13.4 years underwent mitral valve repair of severe MR caused by myxomatous degeneration between 2001 and 2012. Mean preoperative left atrial diameter, LV end-systolic diameter (LVESD), and right ventricular systolic pressure were 41.2 ± 6.9 mm, 34.6 ± 5.4 mm, and 38.4 ± 11.8 mm Hg, respectively. Preoperative LV ejection fraction (LVEF) was greater than 60% in 136 (91%) patients, and none had preoperative atrial fibrillation. Clinical and echocardiographic follow-up averaged 3.3 years and extended to 9.1 years.

Results: There were no perioperative deaths. Five-year survival and freedom from recurrent MR greater than or equal to 2+ were 93.4% ± 3.2% and 94.0% ± 3.2%, respectively. A threshold LVESD indexed to body surface area greater than 19 mm/m(2) (hazard ratio [HR], 3.5 ± 2.0; p = 0.03) and a preoperative right ventricular systolic pressure greater than 45 mm Hg (HR, 3.8 ± 12.1; p = 0.01) were independently associated with postoperative LV dysfunction, defined as a LVEF less than 60%.

Conclusions: Mitral valve repair can be performed with favorable early and late outcomes in patients with asymptomatic severe MR. The presence of minimal LV enlargement and preoperative pulmonary hypertension were associated with postoperative LV dysfunction in this otherwise healthy population. Mitral valve repair may be considered in asymptomatic patients with an indexed LVESD (ILVESD) greater than 19 mm/m(2) or preoperative right ventricular systolic pressure greater than 45 mm Hg.