Clinical Values of Resting Electrocardiography in Patients with Known or Suspected Chronic Coronary Artery Disease: A Stress Perfusion Cardiac MRI Study

Background: Electrocardiography (ECG) is an essential investigation in patients with chronic coronary artery disease (CAD). However, evidence regarding the diagnostic and prognostic value of ECG in this population is limited. Therefore, we sought to determine whether baseline ECG abnormalities were associated with myocardial ischemia and cardiac events in patients with known or suspected chronic CAD. Methods: Consecutive patients with known (n=146) or suspected chronic CAD (n=349) referred for adenosine stress cardiac magnetic resonance (CMR) between 2011 and 2014 were enrolled. Resting ECGs were classified as major, minor and no abnormalities. Predictors of myocardial ischemia on CMR and major adverse cardiac events (MACE) including cardiac death, nonfatal myocardial infarction, hospitalization for heart failure and late revascularization (>180 days after CMR) were evaluated. Results: Average age was 69±11 years (51% men). One hundred and eighty-five patients (37.4%) had major and 154 (31.1%) had minor ECG abnormalities. In patients with suspected CAD, myocardial ischemia was present in 83 patients (23.8%). Multivariable analysis demonstrated major ECG abnormality as the strongest predictor of myocardial ischemia (HR 2.88; 95% CI 1.69-4.92; p<0.001). Adding ECG to clinical pretest probability models improved the prediction of myocardial ischemia in ROC analyses (p=0.04). In the whole cohort (n=495), 91 MACE occurred during the median follow-up period of 4.8 years. Multivariable analysis showed that diastolic blood pressure, history of heart failure, prior revascularization, ischemia, myocardial scarring, and major ECG abnormality were independent predictors of MACE. Conclusion: Abnormal resting ECG is common in patients with known or suspected chronic CAD. ECG had important diagnostic and prognostic values in this population.