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Effects of asymptomatic ischemia on long-term prognosis in chronic stable coronary disease
1Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
Insights
Asymptomatic ischemia detected during ambulatory electrocardiographic monitoring in stable angina patients predicts future cardiac events, including death and myocardial infarction, within 5 years. Monitoring while on medication may mask this risk.
Area of Science:
- Cardiology
- Clinical Medicine
- Diagnostic Monitoring
Background:
- Ambulatory electrocardiographic monitoring for ischemia is linked to poor short-term outcomes in various angina types.
- Chronic stable angina patients with positive exercise tests require prognostic evaluation.
Purpose of the Study:
- To assess the long-term prognostic value of asymptomatic ischemia detected via ambulatory electrocardiographic monitoring in chronic stable angina patients.
- To compare the predictive power of monitoring performed with and without antianginal medication.
Main Methods:
- 138 chronic stable angina patients with positive exercise tests were followed for cardiac events.
- Ambulatory electrocardiographic monitoring was conducted off-medication (n=105) or on-medication (n=59).
- Cox survival analysis identified predictors of death, myocardial infarction, and revascularization.
Main Results:
- Over 37 months, nine deaths, nine myocardial infarctions, and 35 revascularizations occurred.
- Ischemia during off-medication monitoring significantly predicted death and myocardial infarction within 2 years (p=0.02) and all adverse events within 5 years (p=0.009).
- Patients monitored on medication showing no ischemia had more adverse events than those monitored off-medication without ischemia.
Conclusions:
- Asymptomatic ischemia on ambulatory electrocardiographic monitoring predicts adverse cardiac events in stable angina patients.
- Monitoring while on medication may not accurately reflect future coronary event risk if ischemia is masked.
Background:
Ischemia on ambulatory electrocardiographic monitoring has been shown to adversely affect short-term prognoses in patients with unstable angina, after myocardial infarction, and with chronic stable angina.
Methods And Results:
In this long-term study, we followed 138 patients (mean age, 59 +/- 9 years) with chronic stable angina and positive exercise tests for cardiac events (e.g. death, myocardial infarction, percutaneous transluminal coronary angioplasty, or coronary artery bypass graft surgery). In 105 patients, ambulatory electrocardiographic monitoring was performed after all antianginal medication was withheld for 48 hours. In 26 patients, the diagnostic tests were repeated while on their usual medication. In addition to the 105 patients, 33 patients had their monitoring performed only while on their usual medication. During 37 +/- 17 months of follow-up, there were nine deaths, nine myocardial infarctions, and 35 revascularization procedures. In patients monitored off medication, Cox survival analysis showed that the occurrence of ischemia on electrocardiographic monitoring was the most significant predictor of death and myocardial infarction in the subsequent 2 years (p = 0.02) and all adverse events for 5 years (p = 0.009). Patients who were monitored on medication and did not have ischemia (n = 18) appeared to have more adverse events than patients who had no ischemia while being monitored off medication (n = 43).
Conclusions:
Asymptomatic ischemia on ambulatory electrocardiographic monitoring in patients with stable angina predicts death and myocardial infarction for 2 years and all adverse events for 5 years. Monitoring performed while on medication may show no ischemia; however, this may not indicate low risk of future coronary events.