Emergent cardiac outcomes in patients with normal electrocardiograms in the emergency department

Abstract

Background: Emergency physicians (EP) are frequently interrupted to screen electrocardiograms (ECG) from Emergency Department (ED) patients undergoing triage. Our objective was to identify discrepancies between the computer ECG interpretation and the cardiologist ECG interpretation and if any patients with normal ECGs underwent emergent cardiac intervention. We hypothesized that computer-interpreted normal ECGs do not require immediate review by an EP.

Methods: This was a retrospective study of adult (≥ 18 years old) ED patients with computer-interpreted normal ECGs. Laboratory, diagnostic testing and clinical outcomes were abstracted following accepted methodologic guidelines. The primary outcome was emergent cardiac catheterization (within four hours of ED arrival). All ECGs underwent final cardiologist interpretation. When cardiology interpretation differed from the computer (discrepant ECG interpretation), the difference was classified as potentially clinically significant or not clinically significant. Data was described with simple descriptive statistics.

Main findings: 989 ECGs interpreted as normal by the computer were analyzed with a mean age of 50.4 ± 16.8 years (range 18-96 years) and 527 (53%) female. Discrepant ECG interpretations were identified in 184 cases including 124 (12.5%, 95% CI 10.4, 14.7%) not clinically significant and 60 (6.1%, 95% CI 4.6, 7.7%) potentially clinically significant. The 60 potentially clinically significant changes included: ST/T wave changes 45 (75%), T wave inversions 6 (10%), prolonged QT 3 (5%), and possible ischemia 10 (17%). Of these 60, 21 (35%) patients were admitted. Six patients had potassium levels >6.0 mEq/L, with one having a potentially clinically significant ECG change. No patient (0%, 95% CI 0, 0.3%) underwent immediate (within four hours) cardiac catherization whereas two underwent delayed cardiac interventions.

Conclusions: Cardiologists frequently disagree with a computer-interpreted normal ECG. Patients with computer-interpreted normal ECGs, however, rarely had significant ischemic events. A rare number of patients will have important cardiac outcomes regardless of the computer-generated normal ECG interpretation. Immediate EP review of the ECG, however, would not have changed these patients' ED courses.

Keywords: EKG; Emergency department.