Percutaneous mitral valvuloplasty in surgical high risk patients. Among 126 consecutive patients undergoing percutaneous mitral valvuloplasty, 34 were judged to be at high risk for surgery on the basis of age greater than 70 years (n = 13), New York Heart Association functional class IV (n = 11), ejection fraction less than or equal to 35% (n = 3), severe pulmonary hypertension (n = 7), need for associated coronary bypass (n = 4) or additional valve surgery (n = 20) or severe pulmonary disease (n = 3). Baseline features of the high risk group were substantially worse than those of the other patients: age (65 +/- 11 versus 49 +/- 12 years; p = 0.0001) and echocardiographic score (9.4 +/- 1.8 versus 8.2 +/- 1.5; p = 0.005) were higher, whereas cardiac output (2.9 +/- 0.9 versus 4.1 +/- 1.2 liters/min; p = 0.0001) and mitral valve area (0.9 +/- 0.4 versus 1.1 +/- 0.3 mm2; p = 0.002) were lower. Three high risk patients experienced technical failures and three others had major complications. Among the remaining 28 patients, 18 (65%) had a complete hemodynamic success, 4 (14%) an incomplete success and 6 (21%) hemodynamic failure. Stepwise logistic regression analysis retained echocardiographic score as the only factor independently predictive of success. The percent increase in mitral valve area also correlated with echocardiographic score (r = 0.51, p less than 0.01). 