Disparate cardiovascular response to stress tests during isradipine and fosinopril therapy

Abstract

Optimal antihypertensive therapy should control blood pressure at rest and during stress while preserving the physiologic hemodynamic response. In patients with mild to moderate hypertension, the hemodynamic profile and catecholamine response at rest, during isometric, mental, and orthostatic stresses were compared before and 12 weeks after angiotensin-converting enzyme inhibition or calcium channel blockade. Antihypertensive therapy was titrated either with the angiotensin-converting enzyme inhibitor fosinopril (10 to 40 mg; n = 9) or with the calcium antagonist isradipine (5 to 20 mg; n = 10) until diastolic blood pressure <90 mm Hg was achieved. Groups were comparable in race, sex, body mass index, pretreatment mean arterial pressure and response to isometric stress (25% increase in mean arterial pressure) before treatment. At rest, total peripheral resistance was reduced to the same extent (18%) in both groups. After fosinopril, the percent increase in stroke volume was higher and heart rate lower than with isradipine. During isometric stress, the percent increase in mean arterial pressure and cardiac output was higher, with isradipine (p < 0.05) reaching pretreatment levels. Plasma catecholamines were also higher with isradipine (p < 0.05), increasing by 100% with plasma norepinephrine compared with 16% before treatment. During orthostatic stress significant reductions in mean arterial pressure and stroke volume were observed after isradipine but not after fosinopril. Neither medication significantly modified the response to mental stress. Our data suggest that despite a comparable reduction in total peripheral resistance at rest, fosinopril preserves a more physiologic hemodynamic response to isometric and orthostatic stress than isradipine. Moreover, isometric stress may uncover enhanced sympathetic nervous system stimulation during treatment with isradipine but not with fosinopril.