Prevalence and prognostic significance of exercise-induced silent myocardial ischemia detected by thallium scintigraphy and electrocardiography in asymptomatic volunteers

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Abstract

Although a silent ischemic electrocardiographic response to treadmill exercise in clinically healthy populations is associated with an increased likelihood of future coronary events (i.e., angina pectoris, myocardial infarction, or cardiac death), such a response has a low predictive value for future events because of the low prevalence of disease in asymptomatic populations. To examine whether detection of reduced regional perfusion by thallium scintigraphy improved the predictive value of exercise-induced ST segment depression, we performed maximal treadmill exercise electrocardiography (ECG) and thallium scintigraphy (201Tl) in 407 asymptomatic volunteers 40-96 years of age (mean = 60) from the Baltimore Longitudinal Study on Aging. The prevalence of exercise-induced silent ischemia, defined by concordant ST segment depression and a thallium perfusion defect, increased more than sevenfold from 2% in the fifth and sixth decades to 15% in the ninth decade. Over a mean follow-up period of 4.6 years, cardiac events developed in 9.8% of subjects and consisted of 20 cases of new angina pectoris, 13 myocardial infarctions, and seven deaths. Events occurred in 7% of individuals with both negative 201Tl and ECG, 8% of those with either test positive, and 48% of those in whom both tests were positive (p < 0.001). By proportional hazards analysis, age, hypertension, exercise duration, and a concordant positive ECG and 201Tl result were independent predictors of coronary events. Furthermore, those with positive ECG and 201Tl had a 3.6-fold relative risk for subsequent coronary events, independent of conventional risk factors. Thus, in an asymptomatic population, the presence of exercise-induced silent myocardial ischemia increases progressively with age and identifies a small group of subjects with a strikingly high incidence of subsequent coronary events.

Original languageEnglish (US)
Pages (from-to)428-436
Number of pages9
JournalCirculation
Volume81
Issue number2
DOIs
StatePublished - 1990

Keywords

  • asymptomatic volunteers
  • coronary events
  • exercise electrocardiography
  • silent ischemia
  • thallium scintigraphy
  • treadmill exercise

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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