Does the Result of Mitral Valve Repair Depend on the Severity of Mitral Valve Disease?

Introduction:
The prognosis of severe mitral valve disease (MVD) is poor despite medical management. We have reported the good results of mitral valve repair (MVR). However, the optimal period for MVR is not clear. We investigated whether the results of mitral valve repair depend on the severity of MVD.

Materials and methods:
All dogs underwent MVR at our hospital between August 2014 to August 2015. Clinical staging, survival rates and data comparison pre and post-surgery were analyzed.

Results:
111 dogs underwent MVR during the study period. According to the ACVIM/ECVIM classification, 68 were diagnosed with stage C, 23 were Stage B2, 18 were Stage D, and 1 was Stage B1. 102 out of 111 patients were discharged and the overall hospital discharge rate was 92%. Postoperative recovery rates for each cardiac staging were: Stage B1: 100% (1/1), Stage B2: 100% (23/23), Stage C: 89.7% (61/68), Stage D: 88.9% (16/18). Three months postoperative echocardiographic measurements of the left atrial diameter (LAD) and left ventricular diameter (LVD) for dogs in Stage B2 (n=11) and Stage C (n=47) have reduced to almost normal range. The LAD in Stage D (n=8) patients reduced in size but did not return to normal size and the LVD reduction was also limited.

Discussion:
Patients with severe MVD at Stage D showed reduced mitral valve regurgitation but minimal reverse remodeling was observed. MVR offers a good prognosis for early stages of mitral valve insufficiency compared to end-stage disease patients that are refractory to medical therapy.