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Clinical evidence suggesting vasospastic cause of myocardial infarction
Insights
Coronary artery spasm may cause myocardial infarction (MI) in some individuals. Studies show rest angina before MI and postinfarction angina are linked to milder coronary stenosis and variant angina.
Area of Science:
- Cardiology
- Vascular Medicine
- Internal Medicine
Background:
- Myocardial infarction (MI) is a leading cause of mortality worldwide.
- The role of coronary artery spasm in MI pathogenesis remains an area of investigation.
- Variant angina, characterized by coronary vasospasm, is a potential trigger for ischemic events.
Purpose of the Study:
- To investigate the vasospastic etiology of myocardial infarction (MI).
- To analyze the incidence of rest angina preceding MI.
- To characterize clinical features of postinfarction angina and MI occurrence in variant angina patients.
Main Methods:
- Retrospective analysis of 178 MI patients for prior rest angina.
- Evaluation of clinical features and electrocardiographic changes in postinfarction angina.
- Assessment of MI incidence in 97 patients diagnosed with variant angina.
Main Results:
- 34% of MI patients reported prior rest angina, more common with milder coronary stenosis (50% vs. 30%).
- Postinfarction angina with ST elevation occurred in 9% of MI patients, significantly higher in those with milder stenosis (27% vs. 5%).
- MI developed in 9% of variant angina patients, often associated with anginal attacks and less responsive to antispastic agents.
Conclusions:
- Coronary artery spasm is a significant contributing factor to myocardial infarction in a subset of patients.
- Rest angina and postinfarction angina, particularly with ST elevation, suggest vasospastic mechanisms.
- Variant angina patients are at risk for MI, underscoring the importance of managing coronary vasospasm.
Abstract:
To examine the vasospastic cause of myocardial infarction (MI) we studied 1) the incidence of rest angina before MI, 2) clinical features of postinfarction angina and 3) the occurrence of MI in variant angina. 1) Of 178 patients with MI, 60 (34%) experienced rest angina for 1 day to 10 years before the onset of MI. The incidence of rest angina was significantly higher in patients having milder coronary stenosis of 75% or less (15/30, 50%) than in others having severe stenosis of 90% or more (45/148, 30%), p less than 0.05. 2) Postinfarction angina with ST elevation was observed in 16 patients (9%) and ST elevation developed in leads with pathological Q waves in all patients. The incidence of postinfarction angina was significantly higher in those having milder coronary stenosis than in others having severe stenosis, (27% versus 5%, p less than 0.005). Patients with postinfarction angina experienced rest angina before MI more frequently (81%) than others (29%, p less than 0.005). Sublingual nitroglycerin was effective in relieving postinfarction angina attacks and oral calcium antagonist prevented attacks in all patients. 3) MI developed in 9 of 97 patients with variant angina. Six patients had transmural and 3, non-transmural MI. Pathological Q waves and/or coronary T waves appeared in leads where ST elevation was observed during anginal attack. In 7 patients MI developed when antispastic agents were not used and in 2, when angina persisted even under treatment with calcium antagonist. These data strongly suggest that the coronary spasm can be a cause of MI in some patients.