COMPARISON OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITORS AND CALCIUM-ANTAGONISTS IN THE TREATMENT OF MILD TO MODERATE SYSTEMIC HYPERTENSION, ACCORDING TO BASE-LINE AMBULATORY BLOOD-PRESSURE LEVEL

This study was aimed at determining whether baseline ambulatory blood pressure (BP) levels influence the efficacy of angiotensin-converting enzyme inhibitors and calcium antagonists in the same manner. Accordin gly, the ambulatory BP recordings of 236 mild to moderate hypertensive patients who had previously entered a clinical trial and had received either a calcium antagonist (n = 121) or an angiotensin-converting en zyme inhibitor (n = 115) were reviewed. The inclusion criterion was a clinic diastolic BP between 95 and 115 mm Hg at the end of the placebo period. Patients were classified according to the difference between their observed and predicted ambulatory BP (the latter assessed by reg ressing the observed ambulatory BP on the clinic BP). Reduction in amb ulatory systolic and diastolic BP seemed to be greater (p < 0.0001, p = 0.01) in patients receiving an angiotensin-converting enzyme inhibit or than in those who were given a calcium antagonist. However, analysi s of variance showed (1) there was a significant interaction (F = 6.37 p = 0.01) between the pharmacologic class and the baseline systolic a mbulatory BP; and (2) the difference in diastolic ambulatory BP reduct ion between both classes was no longer significant when adjusted for b aseline diastolic ambulatory BP. In patients with higher than predicte d ambulatory BP levels, angiotensin-converting enzyme inhibitors and c alcium antagonists had roughly a similar effect (reduction in systolic BP, 9 +/- 8% vs 7 +/- 6%, p = not significant; reduction in diastolic BP, 11 +/- 8% vs 8 +/- 6%, p = not significant). By contrast, in pati ents with lower than predicted ambulatory BP, angiotensin-converting e nzyme inhibitors decreased ambulatory BP more than calcium antagonists did (systolic BP, 8 +/- 7% vs 1 +/- 7%, p < 0.0001; diastolic BP, 5 /- 8% vs 2 +/- 7%, p = 0.04). Finally, further analysis found the thre shold of efficacy to be 120/80 mm Hg in patients receiving an angioten sin-converting enzyme inhibitor and 135/85 mm Hg in those receiving a calcium antagonist.