Beneficial effects of afterload reduction therapy in patients with congestive heart failure and moderate aortic stenosis.

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Abstract
Patients with congestive heart failure have improved cardiac performance when afterload is reduced by drugs that lower systemic vascular resistance. In the presence of mild-to-moderate aortic stenosis, the response to such drugs is uncertain because the major impedance to left ventricular emptying may occur at the level of the aortic valve. To determine whether vasodilator therapy is useful in this setting, the response to afterload reduction in 11 patients with severe congestive heart failure and reduced aortic valve area was evaluated. All patients underwent catheterization to document the severity of stenosis before study. Reduced valve area was due to native valve stenosis in 3 patients and to the presence of aortic prostheses in 8 patients. A transvalvular gradient was measured in all patients. The peak gradient was 17 .+-. 3 mm Hg (mean .+-. standard error of the mean), and the aortic valve area index was 0.7 .+-. 0.1 cm2/m2. After optimal doses of hydralazine (9 patients) or prazosin (2 patients), cardiac index increased from 2.2 .+-. 0.1 to 3.3 .+-. 0.2 l/min per m2 (P < 0.001) and stroke volume index increased from 28 .+-. 2 to 38 .+-. 2 ml/m2 (P < 0.001). Systemic vascular resistance fell from 1649 .+-. 94 to 1061 .+-. 68 dyn-s/cm5 (P < 0.001), and mean arterial pressure decreased from 93 .+-. 4 to 88 .+-. 4 mm Hg (P < 0.01). Hemodynamics were improved in all 11 patients regardless of valve area. Patients with heart failure and mild-to-moderate aortic stenosis evidently respond favorably to drugs that lower systemic vascular resistance. In such patients, resistance to ventricular emptying is determined predominantly by systemic vascular resistance rather than by aortic valve area.