THE DIAGNOSIS OF PERICARDIAL-EFFUSION AND CARDIAC-TAMPONADE BY 12-LEAD ECG - A TECHNOLOGY-ASSESSMENT

Objective: This study was designed to determine the diagnostic value o f 12-lead ECG for pericardial effusion and cardiac tamponade. Design: Cross-sectional study. Setting: University hospital. Patients: Hospita lized patients with and without pericardial effusion and cardiac tampo nade. Measurements and results: In a blinded manner, we reviewed 12-le ad ECGs from 136 patients with echocardiographically diagnosed pericar dial effusions (12 of whom had cardiac tamponade) and from 19 control subjects without effusions. We examined the diagnostic value of three ECG signs: low voltage, PR segment depression, and electrical alternan s. We found that all three ECG signs were specific but not sensitive f or pericardial effusion (specificity, 89 to 100%; sensitivity, 1 to 17 %) and cardiac tamponade (specificity, 86 to 99%; sensitivity, 0 to 42 %). None of the ECG signs were associated with pericardial effusions o f all sizes, but low voltage was associated with large and moderate pe ricardial effusions (odds ratio=2.5; 95% confidence interval [CI]=0.9 to 6.5; p=0.06) and with cardiac tamponade (odds ratio=4.7; 95% CI=1.1 to 21.0; p=0.004). In contrast, PR segment depression was associated only with cardiac tamponade (odds ratio=2.0; 95% CI=1.0 to 4.0; p=0.05 ), while electrical alternans was not associated with either pericardi al effusion or cardiac tamponade. Conclusions: Low voltage and PR segm ent depression are ECG signs that are suggestive, but not diagnostic, of pericardial effusion and cardiac tamponade. Because these ECG findi ngs cannot reliably identify these conditions, we conclude that 12-lea d ECG is poorly diagnostic of pericardial effusion and cardiac tampona de.