Role of a 12-lead electrocardiogram in the diagnosis of cardiac tamponade as diagnosed by transthoracic echocardiography in patients with malignant pericardial effusion.

BACKGROUND: Few studies have looked at the utility of the 12-lead electrocardiogram (ECG) in diagnosing cardiac tamponade in malignant pericardial effusion (PE). The aim of this study was to determine the sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of 12-lead ECG in diagnosing cardiac tamponade in PE. HYPOTHESIS: Abnormalities on a 12 lead ECG can be used to diagnose or exclude cardiac tamponade in patients with malignant PE.
METHODS: Using echocardiography as the gold standard for diagnosis of cardiac tamponade, we determined the Se, Sp, PPV, and NPV for individual and combinations of the 3 ECG abnormalities (low-voltage complexes, electrical alternans, and sinus tachycardia).
RESULTS: For PEs of all sizes, the Se, Sp, PPV, and NPV for detecting cardiac tamponade were: low-voltage complexes (56%, 74%, 81%, 46%), electrical alternans (23%, 98%, 95%, 39%), and sinus tachycardia (76%, 60%, 79%, 56%), respectively. Presence of all 3 and any of the 3 ECG abnormalities had a Se, Sp, PPV, and NPV of 8%, 100%, 100%, 36% and 89%, 47%, 77%, 69%, respectively, for cardiac tamponade. The odds ratios for cardiac tamponade in PE were 3.7 (95% confidence interval [CI]: 1.65-8.30) for low-voltage complexes, 12.3 (95% CI: 1.58-95.17) for electrical alternans, and 4.9 (95% CI: 2.22-10.80) for sinus tachycardia. Presence of any of 3 ECG abnormalities had an odds ratio of 7.3 (95% CI: 2.9-18.1) for cardiac tamponade.
CONCLUSIONS: In malignant PE, combination of ECG abnormalities can supplement clinical examination in the diagnosis of echocardiographic cardiac tamponade. Due to its low NPV, 12-lead ECG cannot be used as a screening tool to exclude cardiac tamponade with malignant PE.