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Silent ischemia predicts infarction and death during 2 year follow-up of unstable angina
S O Gottlieb1, M L Weisfeldt, P Ouyang
1Department of Medicine, Francis Scott Key Medical Center, Baltimore, Maryland 21224.
Insights
Silent myocardial ischemia, detected via Holter electrocardiogram (ECG), indicates a higher risk of adverse outcomes in unstable angina patients. This condition predicts poor prognosis, including heart attack and revascularization needs, even with medical therapy.
Area of Science:
- Cardiology
- Internal Medicine
- Clinical Research
Background:
- Silent myocardial ischemia is common in unstable angina patients, affecting over 50% despite optimal medical treatment.
- The presence and extent of silent ischemia correlate with increased risks of myocardial infarction and need for revascularization.
- Holter electrocardiographic (ECG) monitoring is a key tool for detecting silent ischemia.
Purpose of the Study:
- To investigate the 2-year prognostic implications of silent myocardial ischemia in patients with unstable angina.
- To determine if silent ischemia, detected by Holter ECG, is a predictor of adverse cardiovascular events.
Main Methods:
- Seventy unstable angina patients were monitored using Holter ECG.
- Patients were divided into two groups: Group I (with silent ischemia) and Group II (without ischemic changes).
- Follow-up was conducted for 2 years to assess outcomes like myocardial infarction and revascularization.
Main Results:
- Silent ischemia was present in 37 patients (Group I), while 33 had no ischemic changes (Group II).
- Group I experienced significantly more myocardial infarctions (10 vs. 1, p<0.01) and revascularizations (11 vs. 5, p<0.05) over 2 years.
- Multivariate analysis identified silent ischemia as the strongest predictor of 2-year outcome.
Conclusions:
- Persistent silent myocardial ischemia in unstable angina patients, despite medical therapy, carries significant adverse prognostic implications.
- Holter ECG detection of silent ischemia is crucial for risk stratification in unstable angina.
- Early identification and management of silent ischemia may be vital for improving long-term outcomes.
Abstract:
Silent myocardial ischemia as detected on Holter electrocardiographic (ECG) monitoring is present in greater than 50% of patients with unstable angina despite intensive medical therapy. The presence and the extent of silent ischemia have been correlated with an increased risk of early (1 month) unfavorable outcome including myocardial infarction and need for coronary revascularization for persistent symptoms. Seventy patients with unstable angina who had undergone continuous ECG monitoring for silent ischemia were followed up for 2 years; 37 patients (Group I) had Holter ECG evidence of silent ischemia at bed rest in the coronary care unit during medical treatment with nitrates, beta-receptor blockers and calcium channel antagonists; the other 33 patients (Group II) had no ischemic ST segment changes (symptomatic or silent) on Holter monitoring. Over a 2 year follow-up period, myocardial infarction occurred in 10 patients in Group I (in 2 it was fatal) compared with one nonfatal infarction in Group II (p less than 0.01 by Kaplan-Meier analysis); revascularization with either coronary bypass surgery or angioplasty for symptomatic ischemia was performed in 11 Group I and 5 Group II patients (p less than 0.05). Multivariate Cox's hazard analysis demonstrated that the presence of silent ischemia was the best predictor of 2 year outcome. Therefore, persistent silent myocardial ischemia despite medical therapy in patients with unstable angina carries adverse prognostic implications that persist over a 2 year period.