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Prevention of reinfarction subsequent to non-Q-wave infarction
1Bugher Foundation Center for Molecular Biology in the Cardiovascular System, Baylor College of Medicine, Houston, Texas 77030.
Insights
Diltiazem significantly reduced recurrent myocardial infarction by 51.2% in patients with non-Q-wave infarction. This cardioprotective drug also lessened angina, demonstrating safety and efficacy in early reinfarction prevention.
Area of Science:
- Cardiology
- Clinical Pharmacology
- Cardiovascular Research
Background:
- Acute non-Q-wave myocardial infarction (MI) poses a risk for early reinfarction and angina.
- Identifying effective cardioprotective strategies is crucial for improving patient outcomes.
Purpose of the Study:
- To evaluate the cardioprotective effects of diltiazem in patients with acute non-Q-wave MI.
- To assess the efficacy of diltiazem in preventing recurrent myocardial infarction and severe angina.
Main Methods:
- A multicenter, double-blind, randomized study involving 576 patients with MB creatine kinase-confirmed acute non-Q-wave MI.
- Patients received either diltiazem (90 mg every 6 h) or placebo for up to 14 days, initiated 24-72 h post-infarction.
- Recurrent MI was defined by elevated MB creatine kinase levels; angina incidence was also monitored.
Main Results:
- Diltiazem reduced the reinfarction rate by 51.2% (5.2% vs. 9.3% in placebo, p=0.0297).
- The drug significantly decreased refractory postinfarction angina by 49.7% (p=0.0345) and angina with ST-T changes by 28% (p=0.0057).
- Adverse events like atrioventricular block and bradycardia were more common with diltiazem, but overall tolerability was good.
Conclusions:
- High-dose diltiazem is safe and well-tolerated in patients with non-Q-wave MI.
- Diltiazem effectively prevents early reinfarction and reduces severe angina in this patient population.
- The findings support diltiazem as a valuable therapeutic option for non-Q-wave MI management.
Abstract:
A multicenter, double-blind, randomized study was performed to evaluate the cardioprotective effects of diltiazem administered to patients with MB creatine kinase-confirmed acute non-Q-wave myocardial infarction. Nine centers enrolled a total of 576 patients, with 287 receiving diltiazem and 289 receiving placebo (90 mg every 6 h). Treatment was started 24-72 h after onset of clinical infarction and continued for up to 14 days. The primary endpoint was recurrent myocardial infarction, which was defined as an abnormal reelevation in plasma MB creatine kinase during the 14-day study period. MB creatine kinase samples were obtained every 12 h after randomization and were assayed by a central core laboratory using the glass bead adsorption method. Recurrent myocardial infarction was documented in 27 patients in the placebo group (9.3%) versus 15 patients in the diltiazem group (5.2%)--reflecting a reduction of 51.2% in the cumulative life-table reinfarction rate (p = 0.0297). The significance of this difference for treatment effect remained at a comparable alpha-level after individual adjustments (Cox model) for age, gender, previous infarction, obesity, site of qualifying infarction, Killip Class at entry, and concurrent use of beta-blocking agents. Diltiazem also reduced the incidence of refractory postinfarction angina necessitating study withdrawal, and angina associated with transient ST-T changes by 49.7% (p = 0.0345) and by 28% (p = 0.0057), respectively. Atrioventricular block, bradycardia, hypotension, and sinus pauses were more common in patients receiving diltiazem, but the drug was well tolerated overall despite the fact that 61% of diltiazem patients were also taking beta-blockers. These results indicate that high-dose diltiazem is well tolerated, safe, and effective in the prevention of early reinfarction and severe angina after non-Q-wave infarction.