Immediate and Late Results of Repeat Percutaneous Mitral Balloon Valvuloplasty for Mitral Restenosis following Previous Percutaneous Mitral Balloon Commissurotomy

This study was a retrospective assessment at Rajaie Cardiovascular, Medical and Research Center, Tehran, Iran, between April 2005 and March 2011, comparing the immediate and late results of initial percutaneous mitral balloon valvuloplasty (PMBV) with repeat PMBV. Totally, 204 patients (mean age= 46±11 years, 85% women) (Group A) who had undergone MBV as an initial procedure were compared with 162 patients (mean age= 43±10 years, 94% women) (Group B) who had undergone repeat MBV due to symptomatic mitral restenosis following previous balloon commissurotomy. The mean follow-up was 47 ± 19 months. The Inoue technique was used in all the patients. Patients in Group B were younger (43.8±10.7 vs. 46.08±11.8 years; P 0.05) and had higher MES (9.09 ± 0.89 vs. 8.54 ± 1; P<0.001) with more subvalvular thickening (2.40 ± 0.49 vs. 2.21±0.44; P<0.001), indicating unfavorable valve anatomy being more pronounced in this group. The immediate outcome regarding hemodynamic results (≥50% decrease of mean transmitral gradient) was satisfactory in both Group A (98%) and Group B (96.3%) (P=0.310). However, the immediate outcome with regard to postprocedural MVA (≥40% increase in preprocedural MVA and mitral regurgitation ≤2/4) was suboptimal in both groups compared to previous studies, especially in Group B which was significantly inferior to Group A (55.6% vs. 76.5%; P=0.001). This difference was still observed when patients with favorable valve morphology (MES≤8) in both groups were compared (56.8% vs. 81.2%; P =0.003). The following are proposed as reasons for the unsatisfactory final MVAs in both groups, especially Group B: 1) greater extent of valve pathology, including leaflet and/or sub-valvular rigidity as the mechanism of restenosis instead of commissural fusion; 2) effect of “commissural calcification grade” on final MVA in mitral valves with an echo score of ≤8; 3) increase in MVA improving leaflet mobility only within limits; 4) not having calculated MVA via Gorlin’s Formula alongside planimetry (which would have been more accurate, especially in those with a history of commissurotomy); 5) occasional inadequacy of the conventional balloon sizing method based on height; and 6) diversity of MBV operators and echocardiography fellows, with different levels of experience. No baseline variables were found to be the independent predictors of the immediate outcome of PMBV. There were no in-hospital deaths, and the incidence in periprocedural and postprocedural complications was low in both groups with insignificant difference. Late clinical outcome (FC<3), although significantly better in Group A (95.1% vs. 88.9%; P=0.027), was favorable in both groups. Loss of valve area, compared with postprocedural MVA, was greater in Group B than in Group A, but the difference was not significant (0.16±0.21 vs. 0.11 ± 0.19 cm2; P=0.1). Late echocardiographic outcome (≤50% decrease of the initial increase in MVA by valvuloplasty) was relatively satisfactory in Group A (77.9%) and just acceptable in Group B (67.3%). Restenosis (a loss of > 50% of the original increase in MVA) was significantly less frequent in Group A (22.1% vs. 32.7%; P=0.022). Logistic regression analysis identified preprocedural mitral echo score (P =0.004), postprocedural mitral valve area (P =0.003), and age (P =0.003) as the independent predictors of restenosis. The patients having undergone re intervention (repeat MBV or MVR) were significantly more in Group B (36.4% vs. 18.6%; P=0.001); however, an acceptable proportion of the patients in this group showed no significant symptomatic deterioration. This study supports repeat PMBV as a feasible procedure in patients with symptomatic restenosis after a first balloon commissurotomy, which can be performed with low risk and can produce acceptable immediate results, mainly a significant decrease in the mean transmitral gradient. It can provide favorable functional improvement and acceptable freedom from restenosis on follow-up in patients with low echo scores and satisfactory postprocedural MVAs and, thus, defer operation (MVR). Considering that repeat MBV is low risk, it can be suggested as a palliative procedure in patients with high risk for surgery.