Abstract 15034: Prediction of Imminent Out-of-Hospital Sudden Cardiac Arrest Based on Warning Symptoms

Introduction: At least 50% of individuals with sudden cardiac arrest (SCA) have warning symptoms. However, such symptoms are also commonly experienced in the community. Comparisons with a control group, currently unavailable, are needed to establish utility of these symptoms for prediction of imminent SCA. Hypothesis: Symptoms documented by emergency medical services (EMS) prior to SCA vs. other 911 calls are distinct. Methods: We performed a case-control analysis from the ongoing Ventura, CA PRESTO study. Cases (ages 18-85) had witnessed SCA attended by EMS (2015-2021). SCA was defined as a sudden, unexpected pulseless condition of likely cardiac origin. Controls were identified from 911 calls that required transport by Ventura County EMS for emergency care but were not SCA. All cases and controls were required to have at least one symptom recorded by EMS that has been previously associated with acute coronary syndrome or SCA (Figure). Results: Among 553 witnessed cases with detailed EMS narratives, 411 (74%) had at least one inclusion symptom (mean age 66 y, 31% female). From a random subset of eligible EMS calls (n=2,794), 1171 controls had ≥1 symptom (mean age 61 y, 55% female). Among cases, dyspnea (41%) and chest pain (33%) were most common; prevalence of other symptoms was <15%. Compared to controls, odds of chest pain, dyspnea, diaphoresis, and seizure-like activity were ≥45% higher in cases (p<0.01) (Figure). Controls’ symptoms were less specific (nausea/vomiting, weakness, dizziness, abdominal symptoms), and palpitations (p<0.01) (Figure). The sensitivity of chest pain (0.33) and dyspnea (0.41) for prediction of SCA was low, but specificities were higher (0.75 and 0.78, respectively). Conclusions: The prevalence of warning symptoms differed significantly between SCA cases and controls. However, sensitivity of individual symptoms was low; additional factors should be investigated to combine with warning symptoms to improve prediction of imminent SCA.