A review of the long-term effects of prazosin and hydralazine in chronic congestive heart failure

In the last two years, six studies using prazosin in doses of 3-32 mg/day for two and 16 months have shown a persistent but variable benefit in 50-80% of those who initially responded favorably. However, serious side-effects occurred in up to 40% and, in many cases, tolerance developed. Mortality was 25-38% in 3-6 months, 50% by one year. In five studies using hydralazine (sometimes combined with long acting nitrates), 150 patients observed from six up to 29 months showed sustained benefit in 26 to 59%, while in many cases hemodynamic values returned to pretreatment values. Again side-effects were considerable, with worsening of angina, fluid retention, gastrointestinal symptomatology and, rarely, lupus erythematodes. Mortality was 28-41% in 10-12 months, higher in non-responders than in responders. Although exercise capacity increased in responders, no data are available today to prove that these vasodilators allow heart failure patients to live longer. Prudence is indicated in patients with congestive heart failure due to coronary artery disease. Furthermore, tolerance development, which only may be surmountable if discontinuation for a few weeks or switching to another drug is possible, is a serious problem limiting chronic vasodilator application.