ABSTRACT
OBJECTIVES: ST-segment elevation (STE) related to benign early repolarization (BER), a common normal variant, can be difficult to distinguish from acute myocardial infarction (AMI). The authors compared the electrocardiogram (ECG) interpretations of these two entities by emergency physicians (EPs) and cardiologists. METHODS: Twenty-five cases (13 BER, 12 AMI) of patients presenting to the emergency department with chest pain were identified. Criteria for BER required four of the following: 1) widespread STE (precordial greater than limb leads), 2) J-point elevation, 3) concavity of initial up-sloping portion of ST segment, 4) notching or irregular contour of J point, and 5) prominent, concordant T waves. Additional BER criteria were 1) stable ECG pattern, 2) negative cardiac injury markers, and 3) normal cardiac stress test or angiography. AMI criteria were 1) regional STE, 2) positive cardiac injury markers, and 3) identification of culprit coronary artery by angiography in less than eight hours of presentation. The 25 ECGs were distributed to 12 EPs and 12 cardiologists (four in academic medicine, four in community practice, and four in community academics [health maintenance organization] in each physician group). The physicians were informed of the patients' age, gender, and race, and they then interpreted the ECGs as BER or AMI. Undercalls (AMI misdiagnosed as BER) and overcalls (BER misdiagnosed as AMI) were calculated for each physician group. RESULTS: Cardiologists correctly interpreted 90% of ECGs, and EPs correctly interpreted 81% of ECGs. The proportion of undercalls (missed AMI/total AMI) was 2.8% for cardiologists (95% confidence interval [CI] = 0.09% to 5.5%) compared with 9.7% for EPs (95% CI = 4.8% to 14.6%) (p = 0.02). The proportion of overcalls (missed BER/total BER) was 17.3% for cardiologists (95% CI = 11.4% to 23.3%) versus 27.6% for EPs (95% CI = 20.6% to 34.6%) (p = 0.03). The mean number of years in practice was 19.8 for cardiologists (95% CI = 19 to 20.5) and 11 years for EPs (95% CI = 10.5 to 12.0) (p < 0.001). CONCLUSIONS: Although correct interpretation was high in both groups, cardiologists, who had significantly more years of practice, had fewer misinterpretations than EPs in distinguishing BER from AMI electrocardiographically.
