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Beta-blockers for the treatment of angina pectoris: indications in relation to pathophysiological mechanisms
S Chierchia1, S Gerosa, J J Glazier
1Cardiovascular Unit, Royal Postgraduate Medical School, Hammersmith Hospital, London, U.K.
Insights
Beta-blockers effectively manage myocardial ischemia in mixed angina patients by reducing transient perfusion reductions. These agents decrease the frequency, severity, and duration of ischemic episodes during daily activities.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Therapeutic strategies for ischemic heart disease depend on underlying pathophysiology.
- Coronary vasoconstriction suggests calcium channel blockers/nitrates; fixed atheroma suggests beta-blockers/revascularization.
Purpose of the Study:
- To investigate the efficacy of beta-blockers in patients with "mixed" angina.
- To explore the mechanisms underlying myocardial ischemia in "mixed" angina.
Main Methods:
- Analysis of recent studies from the laboratory.
- Observation of myocardial ischemia episodes during everyday life in patients with "mixed" angina.
Main Results:
- Beta-blockers significantly reduce the number, severity, and duration of myocardial ischemia episodes.
- Ischemic events in "mixed" angina are linked to transient reductions in myocardial perfusion.
Conclusions:
- Beta-blockers are effective in managing "mixed" angina, even when ischemia is not solely due to increased cardiac work.
- Transient reductions in myocardial perfusion, influenced by cardiac metabolic demand, are key triggers for ischemia in "mixed" angina.
Abstract:
In patients with ischaemic heart disease, therapeutic options should be selected on the basis of pathophysiological considerations. Classically, whereas calcium channel blockers and nitrates should be used in patients whose symptoms are more likely to result from coronary vasoconstriction, beta-blockers and revascularisation procedures should be considered when coronary flow reserve is severely limited by "fixed" atheroma. However, recent studies from our laboratory indicate that in patients with "mixed" angina whose symptoms are thought to be at least partially consequent to coronary vasoconstriction superimposed on atheromatous lesions of different severity, beta-blockers can also be effective in preventing episodes of myocardial ischaemia which occur during everyday life. Although most of these episodes are not apparently caused by an excessive increase in cardiac work, their number, severity, and duration are markedly reduced by beta-blocking agents. From these observations it is argued that, in patients with "mixed" angina, most ischaemic events are likely to be caused by transient reduction of regional myocardial perfusion, occurring for different levels of cardiac metabolic demand. The higher the latter, the more likely the former will be to precipitate clinical ischaemia.