The incidence and prognosis of unrecognized myocardial infarction in the Honolulu, Hawaii, Heart Program
1Honolulu, Hawaii, Heart Program, Kuakini Medical Center 98817.
Insights
Unrecognized myocardial infarctions are common and linked to a worse prognosis. Regular electrocardiogram (ECG) screenings can help detect these silent heart attacks, improving secondary prevention opportunities.
Area of Science:
- Cardiology
- Epidemiology
- Preventive Medicine
Background:
- Clinically unrecognized myocardial infarctions (MI) represent a significant portion of all MIs.
- The long-term prognosis of these silent MIs is not fully understood.
Purpose of the Study:
- To investigate the incidence and 10-year prognosis of unrecognized myocardial infarctions.
- To assess the role of electrocardiographic changes in identifying asymptomatic MIs.
Main Methods:
- Prospective study of 7331 Japanese-American men aged 45-68, free of coronary heart disease at baseline.
- Analysis of electrocardiographic changes over a 6-year follow-up period.
- Ascertainment of nonfatal MIs through repeated examinations and hospital surveillance.
Main Results:
- Asymptomatic MI accounted for 33% of transmural MIs and 22% of all nonfatal MIs.
- The 10-year prognosis for unrecognized MI was worse than recognized MI (risk ratios 1.5-1.7), though not statistically significant.
- Unrecognized MI patients showed increased mortality from all causes, cardiovascular disease, and coronary heart disease.
Conclusions:
- Regular health check-ups including electrocardiograms are important for detecting asymptomatic myocardial infarctions.
- Early detection allows for timely secondary preventive measures.
- Further intervention trials are needed to confirm the comparative effects of secondary prevention on recognized versus unrecognized MI prognosis.
Abstract:
The incidence of clinically unrecognized myocardial infarctions among 7331 Japanese-American men in Hawaii, aged 45 to 68 years and free of coronary heart disease at entry, was studied on the basis of electrocardiographic changes between successive examinations during 6 years of follow-up. The proportion of asymptomatic myocardial infarction accounted for 33% of transmural (Q-wave) myocardial infarctions identified by temporal changes on electrocardiogram and 22% of all nonfatal infarctions ascertained by either repeated examinations or hospital surveillance. The 10-year prognosis of unrecognized infarction, in terms of mortality from all causes, cardiovascular disease, and coronary heart disease, was worse (with risk ratios of 1.5 to 1.7) than that of recognized infarction, even after adjusting for age and other possible determinants, although the differences were not statistically significant. These findings suggest that regular health check-ups with an electrocardiogram would be important to detect asymptomatic myocardial infarction and to increase the opportunity of taking secondary preventive measures. However, the conclusion should await further studies based on intervention trials to determine the comparative effects of the secondary prevention on the prognosis of clinically recognized vs unrecognized infarction.
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