Left atrial (LA) enlargement by 2-dimensional (2-D) echocardiography predicts adverse cardiovascular outcomes. Electrocardiographic (ECG) criteria for LA enlargement are based on M-mode echocardiographic LA diameter, which is inferior to 2-D-derived LA volumes. This study compared established ECG criteria for LA enlargement with atrial volume obtained by 2-D echocardiography to determine if traditional ECG criteria accurately represent LA chamber enlargement, therefore offering a low-cost screening tool. A total of 261 randomly selected patients who underwent electrocardiography and 2-D echocardiography were enrolled. ECG parameters and electronically derived P-wave medians were analyzed with electronic calipers for maximal accuracy. LA volumes by 2-D echocardiography were measured with Simpson's method of discs, with enlargement defined as 32 ml/m(2). Sensitivity and specificity tables and receiver-operating characteristic curves were constructed for each criterion. Univariate and multivariate analyses were performed for predictors of 2-D echocardiographic LA enlargement. LA enlargement was present in 43% of patients. ECG P-wave duration was the most sensitive for the detection of LA enlargement (69%) but had low specificity (49%). Conversely, a biphasic P wave was the most specific (92%) but had low sensitivity (12%). The maximum area under the receiver-operating characteristic curve for any criterion was 0.64, too low to be of clinical utility. In conclusion, established ECG criteria for LA enlargement do not reliably reflect LA enlargement and lack sufficient predictive value to be useful clinically. These results suggest that P-wave abnormalities should be noted as nonspecific LA abnormalities, with the term "LA enlargement" no longer used.