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Effect of diltiazem on symptomatic and asymptomatic episodes of ST segment depression occurring during daily life and
Insights
Diltiazem significantly reduced silent myocardial ischemia in patients with coronary artery disease. This treatment decreased the frequency and severity of asymptomatic ST depression, improving prognostic markers.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Silent myocardial ischemia is a poor prognostic indicator in coronary artery disease.
- Limited controlled data exist on treatment efficacy for silent ischemia.
- The relationship between ST depression, drug effectiveness, and heart rate is not well understood.
Purpose of the Study:
- To evaluate the efficacy of diltiazem in reducing silent myocardial ischemia in patients with stable coronary artery disease.
- To investigate the effect of diltiazem on ST segment depression and heart rate.
Main Methods:
- A multicenter, double-blind, placebo-controlled, cross-over trial involving 60 patients.
- Patients received sustained-release diltiazem (180 mg b.i.d.) or placebo for two 2-week periods.
- Treadmill exercise tests and 72-hour ambulatory ECG monitoring were performed.
Main Results:
- Diltiazem reduced asymptomatic ST depression by over 50% in 70% of patients (p=0.0001).
- The cumulative duration of ST depression significantly decreased with diltiazem (p=0.001).
- Ischemic ST depression occurrence was linked to heart rate changes, not absolute heart rate.
Conclusions:
- Diltiazem effectively reduces the frequency and severity of ischemic ST depression in stable coronary artery disease.
- The drug demonstrated efficacy without circadian variation.
- Diltiazem improved exercise test endpoints and increased the time to ST depression.
Background:
Silent myocardial ischemia is an adverse prognostic marker in patients with coronary disease; however, controlled data on the effect of treatment are sparse and contradictory, and the relations among the occurrence of ST segment depression, drug efficacy, and heart rate are unclear.
Methods And Results:
Sixty patients with stable coronary artery disease, a positive treadmill exercise test and asymptomatic ST segment depression on ambulatory electrocardiographic recording were assessed in a multicenter, double-blind, placebo-controlled, cross-over trial. Treadmill exercise tests and 72-hour electrocardiographic recordings were obtained at the end of two 2-week treatment periods with sustained-release diltiazem 180 mg b.i.d. or equivalent placebo. Episodes of asymptomatic ST depression decreased by 50% or more in 70% of the patients from a median number of 4.5 (range, 0-19) to 1.5 (range, 0-13) (p = 0.0001); their cumulative duration also decreased from 78.5 (range, 0-60) to 24.5 (range, 0-411) minutes (p = 0.001). No circadian variation was found in the efficacy of diltiazem. The occurrence of ischemic type ST segment depression was modulated by changes in heart rate rather than by absolute heart rate. Diltiazem also improved exercise test end points but to a lesser extent. Time to ST segment depression increased to 341 +/- 148 from 296 +/- 154 seconds (p = 0.005). Although less frequent with diltiazem administration (45 versus 54 patients, p less than 0.03), exercise-induced ST depression was more often asymptomatic (98% versus 72% of patients, p less than 0.0001).
Conclusions:
Diltiazem reduces the frequency and severity of ischemic type ST depression in patients with stable coronary artery disease.