Many investigators have reported the results of percutaneous mitral valvuloplasty (PMV) using the Inoue or double-balloon technique, but to date, the immediate and long-term follow-up results of the 2 different procedures have not been compared in a prospective study. Therefore, a prospective, randomized trial was performed in 120 consecutive patients who underwent PMV using Inoue (n = 59; group I) or double (n = 61; group D) balloons. The success rate was 83% in group I, and 89% in group D. The magnitude of changes in mitral valve area and hemodynamic variables was the same in both groups. Immediately after dilation, the long diameter changes of the mitral orifice was greater in group D, and the increase in ejection fraction slope was significantly greater in group D. The duration of the total procedure, and the fluoroscopic time was significantly shorter in group I. The incidence of left-to-right shunt at the atrial level (Qp/Qs > 1.5) was 3.4% in group I and 4.9% in group D. Severe mitral regurgitation (grade > or = 3) occurred in 2 patients in each group. At follow-up, the mitral valve area had significantly decreased at 6 months, but no further changes occurred at 1-year follow-up in both groups. The long diameter of the mitral orifice was greater in group D until 6 months after PMV, but the difference was not apparent at 1-year follow-up. In conclusion, the Inoue and double-balloon techniques obtained equivalent results in the success rate and frequency of complications.(ABSTRACT TRUNCATED AT 250 WORDS)