DEMOGRAPHIC AND CLINICAL PREDICTORS OF ACUTE CORONARY SYNDROME IN PATIENTS WITH PREHOSPITAL CHEST PAIN AND BENIGN ECG FINDINGS

Abstract

Early prehospital recognition of acute coronary syndrome (ACS) has been shown to improve patient outcomes. However, if the prehospital ECG is non-diagnostic for ischemia (i.e., no significant ST elevation or depression), emergency providers have no reliable tools for triaging chest pain. We sought to examine the demographic and clinical predictors of ACS in patients with benign ECG findings. This study prospectively enrolled consecutive, non-traumatic, chest pain patients transported by Emergency Medical Services to one of three UPMC-affiliated tertiary care hospitals in Pittsburgh between 2013 and 2014. We abstracted the following clinical data from patient charts: age; sex; chief complaint (i.e., angina-like pain, dyspnea, palpitation, syncope, gastrointestinal upset, cardiac arrest / pacemaker shock, substance abuse, generalized weakness); past medical history (i.e., hypertension, diabetes, coronary artery disease, prior infarction, and prior coronary revascularization); and presenting vital signs (heart rate, respiratory rate, blood pressure, and oxygen saturation). An independent reviewer examined in-hospital medical records to adjudicate the presence or absence of ACS, defined as the detection of cardiac biomarkers or the presence of ECG, clinical, echocardiographic, or nuclear evidence of acute myocardial injury. Patients with diagnostic ST changes on the prehospital ECG were excluded from the study. We used multivariate logistic regression to identify the predictors of the study outcome. After excluding those with diagnostic ECG (n=87), the final sample included 1,978 patients (age 56±17; 48% females). Overall, 68 patients (3.4%) had ACS with normal or benign ECG findings. In multivariate analysis, age (OR=1.03 [95% CI 1.02-1.05], per 1-year increase), angina-like pain (OR=3.3 [95% CI 1.1-9.7]), palpitation (OR=3.5 [95% CI 1.6-7.8]), and respiratory rate (OR=1.06 [95% CI 1.01-1.11], per 1-unit increase) were the only independent predictors of ACS in this population (all p values < 0.05). Sex, atypical chief complaints, and past medical history were not predictive of the primary outcome. In patients with prehospital chest pain and benign ECG findings, older age, the presence of angina-like pain with palpitation, and elevated respiratory rate are significant predictors of possible ACS. This finding can inform the future education and training of prehospital and emergency providers.