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Echocardiographic Prediction of Left Ventricular Dysfunction After Mitral Valve Repair for Mitral Regurgitation as an Indicator to Decide the Optimal Timing of RepairMatsumura T, et al. J Am Coll Cardiol 2003; 42: 458-63Reviewed by: KW Park, MD
Background: Early surgical repair of the mitral valve (MV) for a patient with severe mitral regurgitation (MR) is recommended, even when the patient may be asymptomatic, because deferring surgery until the patient becomes symptomatic or develops left ventricular (LV) dysfunction often leads to irreversible postoperative LV dysfunction. According to the American College of Cardiology/American Heart Association (ACC/AHA) guidelines (1), class I indications for MV surgery in nonischemic, asymptomatic severe MR are (a) patients with mild LV dysfunction (EF 50 - 60 %) and end-systolic LV dimension (LVDs) of 45 - 50 mm and (b) patients with moderate LV dysfunction (EF 30 - 50 %) and/or LVDs of 50 - 55 mm. This study was conducted to determine useful echocardiographic predictors of long-term LV dysfunction after MV repair, which may be useful in deciding when to operate on these patients. Methods & Results: 171 patients who underwent MV repair for MR due to degenerative pathology between 1991 and 2000 and who had a follow-up echocardiography at least 6 months after surgery were included in the study. Their mean age was 54 ñ 13 years and 63 % were men. Preoperatively, 43 patients were asymptomatic (NYHA classification I), 84 patients were in NYHA class II, 40 were in NYHA class III, and 4 were in class IV. Repair was performed for prolapse of the posterior leaflet or the anterior leaflet. Some (# not specified) required chordal replacement with expanded polytetrafluoroethylene sutures. Most (# not specified) also had a ring annuloplasty. Echocardiographic examinations were followed for a period of 3.9 ñ 2.4 years. The survival rate after MV repair was 97 % at one year and 92 % at 5 years. Survival free of reoperation was 99 % at one year and 94 % at 5 years. After MV repair, both the systolic and diastolic dimensions of LV (LVDs and LVDd) decreased significantly, LVDd decreasing from 61 ñ 7 mm to 51 ñ 7 mm (P < 0.0001) and LVDs decreasing from 38 ñ 7 mm to 33 ñ 8 mm (P < 0.0001). Because of the relatively smaller decrease of LVDs compared to LVDd, the LV EF also decreased from 66 ñ 10 % to 63 ñ 11 %. Postoperative LV dysfunction (defined as LV EF < 50 % after Enriquez-Sarano et al. (2)) was infrequent with an incidence of 12 % and was predicted by preoperative LV EF and LVDs. Patients with preoperative LVEF of 50-55 % had a 25 % incidence of postoperative LV dysfunction and those with preoperative LVEF < 50 % had a 56 % incidence of postoperative LV dysfunction, whereas those with preoperative LVEF > 55 % had an 8 % incidence of postoperative LV dysfunction. For LVDs, the major increase in the incidence of postoperative LV dysfunction occurred at LVDs of 40 mm. Those with preoperative LVDs < 40 mm had a 6 % incidence of postoperative LV dysfunction, whereas those with preoperative LVDs > 40 mm had a 27 % incidence. Discussion and Comments: The findings of this study are consistent with earlier studies (2-6), which also found that preoperative LV EF (< 50-60 %) and LVDs (> 40-45 mm) were predictive of postoperative LV dysfunction. As argued by Wisenbaugh in an editorial accompanying this paper (7), such findings speak for an aggressive early surgical correction of severe mitral regurgitation, whenever repair is surgically feasible, even if the patient is asymptomatic. Asymptomatic patients with severe MR should be on echocardiographic surveillance, so that their mitral valves may be repaired before LVDs increases > 40 mm or LV EF falls below 55 % and the risk for postoperative LV dysfunction jumps significantly. Echocardiographic surveillance should elucidate the anatomy of the valve, LV EF and dimensions, and the feasibility of valve repair. With advances in surgical techniques and anesthetic management, reported early mortality from such surgery ranges from 1.4 - 2.9 % (7) and the 20-year survival rate is similar (48 %) to that for a normal population with the same age distribution (56 ñ 10 years) (8). Whereas the ACC/AHA guidelines list asymptomatic patients with chronic MR with preserved LV function in whom repair is highly likely as having a class IIb indication for MV surgery (1), Wisenbaugh argues that they should be considered to have a class I indication. Conversely, whereas patients with severe MR with moderate LV dysfunction (EF 30-50 %) and/or LVDs 50-55 mm are said to have a class I indication for MV surgery (1), such patients incur a very high risk of postoperative LV dysfunction (56 % incidence if preoperative LV EF < 50 % in the present study). Wisenbaugh argues that one may need to be more selective in taking such patients to MV surgery. It is notable also that the LV dimensions decreased significantly after MV repair. This would imply decreased afterload, increased contractility, or both. Classically, it has been taught that LV afterload increases following correction of MR, because the low-impedance outflow back to the left atrium is no longer available. Data such as Matsumura et al.'s would imply that after MV repair for degenerative mitral valve disease, either there is no increase in LV afterload or there is a significant increase in contractility to decrease the LV dimensions despite an increase in afterload. References:
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