The effect of the vasodilator prazosin vs placebo on exercise duration until marked dyspnea, and on left ventricular function measured by echocardiography, was evaluated in a double-blind, randomized study in 24 patients with chronic left ventricular failure despite digitalis and diuretic therapy. Compared with the double-blind placebo, prazosin reduced resting systolic and diastolic blood pressure and systolic blood pressure times heart rate, improved clinical symptoms, decreased cardiothoracic ratio measured by chest roentgenography, decreased left ventricular and left atrial dimensions, improved ejection fraction and Vcf measured by echocardiography, and improved treadmill exercise duration. All 12 patients taking prazosin had greater than or equal to 20% improved treadmill exercise duration; none of 12 receiving placebo improved. In six of 12 patients taking prazosin, roentgenographic evidence of pulmonary venous congestion disappeared compared with none of the patients on placebo. These data suggest that prazosin may be effective in treating chronic left ventricular failure.

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The effect of timolol vs placebo on the frequency of anginal episodes, nitroglycerin consumption and exercise performance was investigated in a double-blind, randomized, crossover study in 23 patients with angina pectoris. The optimal dose of timolol (10-30 mg twice daily) for each patient was titrated by exercise studies. Compared with placebo, timolol decreased the weekly number of anginal attacks and the weekly number of nitroglycerin tablets consumed, reduced the resting heart rate, systolic and diastolic blood pressure, and product of systolic blood pressure times heart rate, decreased the heart rate, systolic and diastolic blood pressure, and product of systolic blood pressure times heart rate at the onset of angina pectoris or marked fatigue, prolonged exercise duration, and diminished electrocardiographic evidence of myocardial ischemia. Timolol is an excellent antianginal agent when prescribed twice daily, with the optimal dose titrated by exercise studies.

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