DISPARATE CARDIOVASCULAR-RESPONSE TO STRESS TESTS DURING ISRADIPINE AND FOSINOPRIL THERAPY

Optimal antihypertensive therapy should control blood pressure at rest and during stress while preserving the physiologic hemodynamic respon se. In patients with mild to moderate hypertension, the hemodynamic pr ofile and catecholamine response at rest, during isometric, mental, an d orthostatic stresses were compared before and 12 weeks after angiote nsin-converting enzyme inhibition or calcium channel blockade. Antihyp ertensive therapy was titrated either with the angiotensin-converting enzyme inhibitor fosinopril (10 to 40 mg; n = 9) or with the calcium a ntagonist isradipine (5 to 20 mg; n = 10) until diastolic blood pressu re < 90 mm Hg was achieved. Groups were comparable in race, sex, body mass index, pretreatment mean arterial pressure and response to isomet ric stress (25% increase in mean arterial pressure) before treatment. At rest, total peripheral resistance was reduced to the same extent (1 8%) in both groups. After fosinopril, the percent increase in stroke v olume was higher and heart rate lower than with isradipine. During iso metric stress, the percent increase in mean arterial pressure and card iac 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 isradipin e but not after fosinopril. Neither medication significantly modified the response to mental stress. Our data suggest that despite a compara ble reduction in total peripheral resistance at rest, fosinopril prese rves a more physiologic hemodynamic response to isometric and orthosta tic stress than isradipine. Moreover, isometric stress may uncover enh anced sympathetic nervous system stimulation during treatment with isr adipine but not with fosinopril.