Related Experiment Videos
[Myocardial infarction beyond the 48 first hours: treatment with calcium channel antagonists]
F Delahaye1, G de Gevigney, M Ovize
1Hôpital cardiovasculaire et pneumologique Louis-Pradel, Lyon.
Insights
Calcium channel blockers reduce cardiac workload and improve blood flow. Clinical trials show mixed results for reducing mortality and reinfarction after myocardial infarction, with some benefits observed for verapamil.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Calcium channel blockers (CCBs) reduce myocardial oxygen demand by decreasing blood pressure, heart rate, and contractility.
- CCBs improve coronary perfusion by relieving vasospasm and dilating collateral vessels, potentially aiding ischemic zones.
Purpose of the Study:
- To evaluate the efficacy of calcium channel blockers in reducing mortality and reinfarction rates following myocardial infarction.
- To synthesize findings from multiple clinical trials investigating CCBs in post-myocardial infarction patients.
Main Methods:
- Review of clinical trials including Myocardial Infarction Study (lidoflazine), Danish Verapamil Infarction Trial I & II (verapamil), and Secondary Prevention Reinfarction Israeli Nifedipine Trial (nifedipine).
- Analysis of patient data from trials involving verapamil, nifedipine, and diltiazem compared against placebo groups.
- Follow-up periods ranged from 6 months to 5 years, with interventions initiated at varying times post-infarction.
Main Results:
- The Myocardial Infarction Study found no significant difference in mortality with lidoflazine.
- Danish Verapamil Infarction Trials showed non-significant reductions in mortality and reinfarction with verapamil.
- DAVIT II demonstrated a statistically significant reduction in recurrences (p=0.04) with verapamil.
- Nifedipine trials (SPRINT, Israeli trial) reported similar mortality and reinfarction rates between nifedipine and placebo groups.
Conclusions:
- Clinical trial results for calcium channel blockers in post-myocardial infarction secondary prevention are inconsistent.
- While some trials suggest potential benefits for specific agents like verapamil in reducing reinfarction, overall mortality benefits are not consistently demonstrated.
- Further research may be needed to clarify the role of different CCBs in managing patients post-myocardial infarction.
Abstract:
Calcium channel blocking agents prevent calcium entering cardiac and smooth muscle cells. With reduction of the blood pressure, heart rate and myocardial contractility, they reduce myocardial oxygen demand. By relieving spasm and coronary constriction, and dilating the collateral coronary vessels, they improve perfusion of the ischemic zones. The results in experimental infarction are contradictory: the reduction in the infarct size and ischaemia is not constant. In the Myocardial Infarction Study, a trial of lidoflazine in 1792 subjects followed up for an average of 5 years, there was no significant difference between the mortality rates of the two groups. In the Danish Verapamil Infarction Trial I, which included 436 subjects receiving 360 mg/day of verapamil or placebo, the 6 months mortality was less (NS) in the verapamil group (12.8%) than in the placebo group (13.9%) as was the reinfarction rate (7.8% versus 9.2%; NS). In the DAVIT II trial of 1775 subjects, treatment was introduced 9 +/- 2.7 days after admission. Mortality was lower (NS) in the verapamil group (11.1%) than in the placebo group (13.8%) and the recurrences were less common (p = 0.04) in the treatment group (11.0%) than with placebo (13.2%). The Secondary Prevention Reinfarction Israeli Nifedipine Trial is a comparison of Nifedipine 30 mg/day and placebo introduced 7-21 days after infarction in 2276 subjects. After 10 months, the mortality and reinfarction rate were similar in both groups, as in the SPRINT II trial (60 mg/day of nifedipine or placebo) at 6 months. In the Multicenter Diltiazem Postinfarction Trial of 2466 patients, Diltiazem 240 mg/day or placebo was administered 3 to 15 days after infarction.(ABSTRACT TRUNCATED AT 250 WORDS)