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New concepts in ischemia prevention
1Department of Internal Medicine, Karl Franzens University, Graz, Austria.
Insights
Calcium channel blockers effectively reduce myocardial ischemia in coronary heart disease patients. However, caution is advised for those with postinfarction left ventricular dysfunction, with specific agents requiring combination therapy for optimal results.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Transient myocardial ischemia stems from coronary artery obstruction or diminished flow reserve.
- Calcium channel blockers are used for stress-induced ischemia in coronary heart disease.
- Concerns exist regarding calcium antagonists in postinfarction left ventricular systolic dysfunction.
Purpose of the Study:
- To evaluate the efficacy of calcium antagonists in managing myocardial ischemia.
- To compare different classes of calcium antagonists and their effects on ischemic burden.
- To explore the role of ACE inhibitors in ischemia and hypertrophy.
Main Methods:
- Review of existing studies on calcium antagonists and ACE inhibitors in myocardial ischemia.
- Analysis of drug effects based on heart rate changes and combination therapy.
- Consideration of ischemic threshold for individualized treatment strategies.
Main Results:
- Calcium antagonists reduce stress-induced ischemia in patients with normal or reduced left ventricular function.
- Diltiazem (rate-reducing) effectively reduces ischemic burden as monotherapy.
- Dihydropyridines (rate-increasing) require beta-blocker combination for similar effects.
- ACE inhibitors show no significant benefit in stress-induced ischemia but may reduce total burden.
- Calcium blockers and ACE inhibitors may regress left ventricular and vascular hypertrophy, but ischemia reduction is unproven.
Conclusions:
- Calcium channel blockers are beneficial for stress-induced ischemia, with specific considerations for heart rate effects and patient conditions.
- Individualized therapy based on ischemic threshold is crucial for 24-hour ischemia control.
- Further research is needed to confirm the anti-ischemic effects of ACE inhibitors and calcium blockers in specific hypertrophic conditions.
Abstract:
Transient myocardial ischemia may result from obstruction to flow in the large epicardial coronary arteries or diminished flow reserve due to small vessel disease or left ventricular hypertrophy. In patients with coronary heart disease, calcium blockers have proven to reduce stress induced ischemia in patients with normal left ventricular function and in those with ischemic cardiomyopathy. However, recent studies indicate a need for caution when giving calcium antagonists to patients with postinfarction left ventricular systolic dysfunction. Moreover, calcium antagonists that reduce heart rate (diltiazem) are able as a monotherapy to reduce total ischemic burden. Calcium antagonists that may increase rate (dihydropiridines) have to be combined with beta-blockers to achieve this goal. For 24-h control of ischemia the ischemic threshold should be determined for a differentiated therapy in the individual patient. Is the ischemic threshold of the majority of episodes lower than the exercise threshold, a calcium blocker should work. Angiotensin-converting enzyme (ACE) inhibitors are not effective in stress-induced ischemia, but may reduce total ischemic burden, although this effect is not significant. In patients with left ventricular hypertrophy and/or small vessel disease, calcium blockers and ACE inhibitors are probably effective in regression of left ventricular hypertrophy and vascular hypertrophy. However, it remains to be shown that ischemia is reduced by these drugs.