Percutaneous transvenous mitral balloon valvotomy (PTMV) optimal results are usually achieved when echocardiographic Wilkins score (WS) is ≤8. WS from 9 to 11 represent a gray zone in which only some patients have good results.

The aim of this study was to determine the early and long term results of this procedure in patients with WS 8 or less and at the gray WS zone.

Retrospective review of clinical records of patients with rheumatic MS submitted to PTMV from January 1990 to December 2010. Follow-up was obtained by clinical records when available. Procedure was considered unsuccessful when post-procedure MV area (MVA) was <1.5cm².

We analyzed data for 378 patients with a WS ≤11, 80.5% were women. Mean age at the time of repair was 33 years [10 to 76 years] and the mean follow up time was 74 months. Before the procedure, 33.9% had a WS in the gray zone. They were older (36 years vs. 31 years, p<0.001) with a frequent history of mitral valvuloplasty (34.4% vs. 12%, p <0.001). Males presented more in the gray zone (25.8% vs 16.8%, p = 0.038) while pregnant women had a WS ≤8 (20.4% vs. 11.7%, p= 0.035). Patients in the gray zone presented more frequently with atrial fibrillation (39.1% vs. 21.2%, p< 0.001). There was no differences regarding the functional status or the baseline echocardiographic MVA measurement by planimetry (1.07cm² vs 1.05cm², p=0.26).

PTMV was safe in the two groups with same rates of success but a lower mitral surface gain in the gray zone group (0.88cm² vs. 1.05cm², p<0.001).

During follow up, patients in the gray zone had significantly lower event free survival (freedom from death, systemic embolism and restenosis) (58.6% vs. 69.2%, p<0.001) and had a higher mortality (3.9% vs 0.8%, 0.023), higher rates of restenosis (33.6% vs. 17.8%, p<0.001) and required more frequently a mitral valve replacement (16.4% vs. 8.9%, p= 0.005)

PTMV was a safe procedure in both WS groups. Optimal results patients with a WS≤8 zone. Patients with a WS 9-11 experienced worse outcomes during follow up.