Comparison of results of percutaneous double balloon mitral valvotomy with open surgical valvotomy. The results in 85 patients with mitral stenosis who had successful balloon mitral valvotomy, using 20 + 20 mm diameter balloon catheters, were compared with the results achieved in a group of 85 patients who had elective open mitral valvotomy. Both groups were of similar age. The mean mitral valve area increased from 0.9 +/- 0.2 to 2.0 +/- 0.3 cm2 (p less than 0.001) after balloon valvotomy. The mean mitral valve area increased from 0.9 +/- 0.3 to 2.2 +/- 0.6 cm2 (p less than 0.001) following surgical open valvotomy. Overall, results of balloon mitral valvotomy are comparable to open surgical mitral valvotomy.