Disagreement in the interpretation of electrocardiographic ST segment elevation: A source of error for emergency physicians?

Evaluation of the electrocardiogram (ECG) is a complex, subjective process with the potential for interobserver disagreement. The objective of this study was to determine the ECG patterns with discrepant interpretations, the rates of disagreement in the determination of both the presence of ST segment elevation (STE) and morphology. ECGs were reviewed in a retrospective fashion by attending EPs for STE and waveform morphology. Those ECGs that were interpreted in a discrepant fashion were then analyzed to detect patterns of disagreement. ECGs from 599 patients were reviewed. Two hundred eleven patients (35.2% of the total patient population surveyed) had STE as determined by at least one attending EP; 40 (19% of the STE population) patients had STE determined by 1 EP, 21 (10% of the STE population) patients by 2 EPs, and 150 (71% of the STE population) patients by 3 EPs. The STE of 61 (28.9%) ECGs were interpreted in a discrepant fashion. The average STE was 1.31 mm per lead for ECGs with disagreement and 2.93 mm per lead for ECGs with agreement (P <.05). ECGs with reciprocal ST depression were more likely to have agreement with regard to the STE (P <.05). Fourteen ECGs (8.2% of 171 ECGs with STE determined by at least 2 EPs) had ST segment morphology interpreted in a discrepant fashion. Disagreement in the determination of electrocardiographic ST segment elevation by EPs occurs frequently and is related to the amount of STE present on the ECG. Electrocardiographic patterns responsible for this interpretive disagreement of ST segment elevation can represent an unfortunate but potentially predictable source of error in emergency medical care.