Ultra-Short ECG Indices in Patients Presenting with Epigastric Pain—An Orientation Tool for Diagnosis in the Emergency Department

Background and Objectives: Abdominal pain, particularly epigastric pain, is a leading cause of emergency department (ED) visits and encompasses a wide differential diagnosis, ranging from mild conditions such as gastritis and reflux disease to life-threatening etiologies such as acute abdomen and acute myocardial infarction (MI). Epigastric pain is often associated with stress, inflammation, and visceral signaling, processes mediated by the autonomic nervous system (ANS). Changes in ANS activity can be captured by heart rate variability (HRV), a non-invasive measure derived from cardiac rhythm. In this study, we conducted retrospective research to evaluate the prognostic significance of HRV in ED patients presenting with epigastric pain. Materials and Methods: Retrospective analysis of patients diagnosed with epigastric pain in the ED at Rambam Health Care Campus in 2014. Ultra-short heart rate variability (usHRV) indices were calculated from a 10 s ED electrocardiogram and correlated with mortality, disease severity, and disease origin. Results: 300 patients were included in this study. Due to a very low short-term mortality rate, usHRV could not be reliably assessed for this outcome. The mortality rate throughout the follow-up period of the study was 17.4%, with a median of 8.4 years. No significant association was found between long-term mortality and standard deviation of normal-to-normal intervals (SDNN) or root mean square of successive differences (RMSSD). In multivariate logistic analysis, high RMSSD significantly increased the risk for acute abdomen (RMSSD-adjusted odds ratio (AOR): 1.021, p-value: 0.022, Area under the curve (AUC): 73%), while high RMSSD decreased the risk for acute MI (RMSSD AOR: 0.807, p-value: 0.026, AUC: 83.6%). Conclusions: Ultra-short HRV did not predict long-term mortality in patients presenting with epigastric pain. However, RMSSD was independently associated with both acute abdomen and acute MI. These findings suggest that usHRV parameters may serve as a supportive tool in the ED to aid differentiation between abdominal and cardiac causes of epigastric pain, particularly in high-risk clinical scenarios.