Comparison of subgroups assigned to medical regimens used to suppress cardiac ischemia (the Asymptomatic Cardiac Ischemia Pilot [ACIP] Study)

Abstract

This report focuses on the subset of 235 patients from the Asymptomatic Cardiac Ischemia Pilot (ACIP) study receiving randomly assigned medical therapy to treat angina and suppress ischemia detected on ambulatory electrocardiography: 121 patients received the sequence of atenolol and nifedipine, and 114 diltiazem and isosorbide dinitrate. After 12 weeks of therapy, the primary end point (absence of ambulatory electrocardiographic (ECG) ischemia and no clinical events) was reached in 47% of atenolol/nifedipine- versus 31% of diltiazem/isosorbide dinitrate-treated patients (adjusted p = 0.03). A trend to increased exercise time to ST depression was seen in the atenolol and nifedipine versus diltiazem and isosorbide dinitrate regimens (median treadmill duration 5.8 vs 4.8 minutes; p = 0.04). However, when adjusted for baseline imbalances in ambulatory ECG ischemia, the 2 medical combinations were similar in suppression of ambulatory ECG ischemia. In both medication regimens, an association between mean heart rate and ischemia on ambulatory electrocardiography after 12 weeks of treatment was observed so that patients on either regimen with a mean heart rate > 80 beats/min had ischemia detectable almost twice as often as those with a mean heart rate < 70 beats/min (p < 0.001).