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A prognostic comparison of asymptomatic left ventricular hypertrophy and unrecognized myocardial infarction: the
Insights
Electrocardiogram-left ventricular hypertrophy (ECG-LVH) and unrecognized myocardial infarction (ECG-MI) are similar subclinical conditions. Both increase the risk of future cardiovascular disease, including heart attack, stroke, and death.
Area of Science:
- Cardiology
- Preventive Medicine
- Epidemiology
Background:
- Subclinical electrocardiogram (ECG) abnormalities, such as left ventricular hypertrophy (ECG-LVH) and myocardial infarction (ECG-MI), may predict future cardiovascular events.
- The Framingham Heart Study provides long-term data on cardiovascular disease incidence and risk factors.
Purpose of the Study:
- To compare the incidence, predisposing characteristics, and prognostic implications of asymptomatic ECG-LVH and unrecognized ECG-MI.
- To assess the association of these subclinical ECG findings with subsequent clinical coronary heart disease, heart failure, stroke, and mortality.
Main Methods:
- Analysis of 30-year follow-up data from the Framingham Heart Study.
- Identification of subjects with incident ECG-LVH and unrecognized ECG-MI based on biennial ECG examinations.
- Comparison of event rates and risk factors between ECG-LVH and ECG-MI groups, and with the general population.
Main Results:
- ECG-LVH occurred approximately twice as frequently as unrecognized ECG-MI among subjects initially free of clinical coronary heart disease.
- Both ECG-LVH and ECG-MI were associated with increased risks of subsequent clinical coronary heart disease, cardiac failure, stroke, and all-cause mortality.
- ECG-LVH conferred a particularly higher risk for cardiovascular death in women compared to ECG-MI.
Conclusions:
- Asymptomatic ECG-LVH and unrecognized ECG-MI represent similar subclinical cardiovascular conditions with comparable adverse prognoses.
- These ECG abnormalities share similar predisposing factors, including male sex and hypertension.
- Both ECG-LVH and ECG-MI serve as important indicators for increased risk of overt cardiovascular disease and mortality.
Abstract:
In 30 years of follow-up in the Framingham study, routine biennial ECG examinations revealed 315 subjects with ECG-LVH and 164 with unrecognized ECG-MI without previous cardiac explanation. Among subjects initially free of clinically evident coronary heart disease and both ECG abnormalities, the incidence of ECG-LVH was about double that of ECG-MI. Both events exhibited a male predominance and hypertensive subjects were more vulnerable to each. In subjects with asymptomatic ECG-LVH and ECG-MI, the 10-year, age-adjusted incidence of clinical coronary heart disease was greater than the rate experienced by the general Framingham sample. Rates for ECG-LVH were almost as large as those for ECG-MI. Cardiac failure and stroke also occurred more frequently among subjects with either ECG abnormality, and rates for ECG-LVH exceeded those for ECG-MI. Death from coronary heart disease, and sudden death in particular, was also increased two- to fourfold with similar risks for ECG-LVH and ECG-MI. ECG-LVH carried a significantly greater risk than ECG-MI for cardiovascular deaths in women. These findings suggest that ECG-LVH and ECG-MI are similar subclinical events with respect to predisposing characteristics and prognosis for subsequent overt cardiovascular disease including clinical manifestations of coronary heart disease.