Follow-up of patients with low output, low gradient hemodynamics after percutaneous balloon aortic valvuloplasty: the Mansfield Scientific Aortic Valvuloplasty Registry. Symptomatic patients with a low cardiac output and low aortic valve gradient have a poor prognosis but are at high risk for aortic valve surgery. The outcome of percutaneous balloon aortic valvuloplasty in this subgroup of patients is unclear. Therefore, 67 patients (group 1) underwent percutaneous balloon aortic valvuloplasty between December 1, 1986 and November 1, 1987 who had a low cardiac index (less than 2.5 liters/min per m2) and a low aortic valve gradient (less than or equal to 40 mm Hg) before the procedure. The results were compared with 200 patients (group 2) who had a low cardiac index but not a low aortic valve gradient (greater than 40 mm Hg) before the procedure and who had similar baseline presenting symptoms. After balloon aortic valvuloplasty, there was a greater decrease in aortic valve gradient in patients in group 2 than in patients in group 1 (mean +/- SD -33.0 +/- 16.7 mm Hg and -14.6 +/- 6.9 mm Hg, respectively; p less than 0.001) although there was no significant difference in improvement in estimated aortic valve area (0.31 +/- 0.21 and 0.31 +/- 0.22 cm2, respectively; p = NS). In-hospital mortality was 11.9% for patients in group 1 which was not significantly different from the 7.5% mortality for patients in group 2. However, the actuarial probability of survival at 12 months for patients who survived the initial hospitalization was 46% in group 1 and 64% in group 2 (p less than 0.05). Moreover, at follow-up (mean 8.8 months) 64% of surviving group 1 patients displayed clinical improvement, compared with 70% of surviving group 2 patients. 