Predictability of antihypertensive efficacy of selective β1 blockers

The possibility that hemodynamic and biohumoral factors may help predict the antihypertensive effectiveness of selective α₁ blockers was investigated. The effects of 3 wk of treatment with two selective β₁ blockers, metoprolol and atenolol, were observed in 54 patients with mild or moderate essential hypertension. No significant difference between the hemodynamic effects of the two drugs was found. The percent fall in systolic blood pressure induced by the two correlated strongly with the pretreatment values of the chronotropic response to isoproterenol and with the pretreatment values of cardiac output, heart rate, and plasma renin activity (PRA). There was no correlation between the decrease in systolic blood pressure induced and initial 24-hr urinary catecholamine output, total peripheral resistance, and plasma aldosterone. Percent fall in diastolic blood pressure correlated only with the pretreatment levels of PRA. Our results support the view that the hypotensive effect of β₁ blockers are predictable on the basis of the pretreatment values of chronotropic response to isoproterenol, PRA, heart rate, and cardiac output.