Arterial dilators in mitral regurgitation: effects on rest and exercise hemodynamics and long-term clinical follow-up.

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Abstract
Sixteen patients with severe mitral regurgitation were studied to determine the acute effects of hydralazine on cardiac performance at rest and during exercise and to assess the long-term clinical response to therapy. At rest, optimal-dose hydralazine (range 50-225 mg) reduced systemic vascular resistance from 1385 .+-. 88 to 964 .+-. 76 dyn-s-cm5 (mean .+-. SEM [standard error of the mean]) (P < 0.001). As a result, pulmonary artery wedge pressure decreased from 18 .+-. 2 to 15 .+-. 2 mm Hg (P < 0.025), cardiac index from 2.5 .+-. 0.1 to 3.7 .+-. 0.2 l/min per m2 (P < 0.001) and stroke volume index increased from 30 .+-. 2 to 39 .+-. 2 ml per m2 (P < 0.001). The effects of hydralazine on exercise hemodynamics were evaluated in 12 patients. Before treatment, the patients exercised at increasing work loads until limited by symptoms. After hydralazine therapy, exercise was repeated at identical work loads. Although exercise alone resulted in a reduction in systemic vascular resistance, from 1385 .+-. 88 to 1111 .+-. 118 dyn-s-cm5, the addition of hydralazine caused a further reduction in resistance, from 1111 .+-. 118 to 755 .+-. 72 dyn-s-cm5 (P < 0.005). Hydralazine reduced pulmonary artery wedge pressure during exercise from 27 .+-. 2 to 21 .+-. 1 mm Hg and increased cardiac index from 3.7 .+-. 0.3 to 4.9 .+-. 0.3/min per m2 (both P < 0.001) and stroke volume index from 36 .+-. 3 to 45 .+-. 2 ml per m2 (P < 0.005). All 16 patients were discharged on hydralazine therapy and their clinical course was followed. A marked improvement in symptoms from New York Heart Association functional class III-VI to class I-II, which was sustained for at least 6 mo., occurred in 7 patients (44%). One patient improved from class IV to class III. The mean follow-up in these 8 patients was 13 .+-. 4 mo. In 4 of the 8 remaining patients, hydralazine was discontinued because of intolerable side effects. Mitral valve surgery was performed in 3 of these patients as well as in 4 patients who demonstrated an initial hemodynamic response to therapy but failed to experience symptomatic improvement. Hydralazine therapy results in substantial improvement in cardiac performance in patients with mitral regurgitation. The beneficial effects seen at rest are maintained during exercise. The acute improvement in hemodynamics resulted in sustained clinical improvement in 1/2 the patients with mitral regurgitation; the other 1/2 needed valve surgery. Arterial dilator therapy is beneficial for some patients with severe mitral regurgitation.