Abstract 335: Distinguishing Cardiac From Non-Cardiac Causes of Sudden Death: The Value of Novel Factors to Identify Risk of SCD

Introduction: Identifying those at risk for Sudden Cardiac Death (SCD) is imperative to prevent future events. There may be risk factors (RFs), triggers or warning symptoms preceding the SCD that could help identify those at greatest risk. Methods: This retrospective study included out-of-hospital cardiac arrests (OHCAs) of “no obvious cause” in the Greater Toronto Area, ages 2-45 from 2009-2012. Expert reviewers systematically adjudicated EMS, coroner, autopsy, toxicology and police reports to classify the etiology of arrest as SCD or SD due to non-cardiac etiologies (non-cardiac SDs). We compared past medical history, triggers and symptoms in the adjudicated SCD and non-cardiac SD groups and assessed their potential associations with SCD. Results: 872 OHCAs were classified as SCDs (488; 56%) or non-cardiac SDs (384; 44%). The SCDs were mostly CAD (203; 41.6%), structural (155; 31.8%), congenital (8; 1.6%) and primary arrhythmic (76; 15.6%). The non-cardiac SDs were due to acute infection (67; 17.4%), metabolic (75, 19.5%), epilepsy (69, 18.0%), vascular (106; 27.6%) and respiratory (35, 9.1%). Cardiac RFs and exercise as a trigger were observed significantly more in SCDs vs. non-cardiac SDs (Table 1). Symptoms ≤24 hours prior were similar between groups except for chest pain and diaphoresis. After adjusting for patient and resuscitation variables, factors associated with increased risk of SCD were: increasing age (OR 1.03; 95%CI 1.01-1.05), male sex (OR 1.90; 95%CI 1.30-2.70), HTN (OR 1.80; 95%CI 1.11-3.10), smoking (1.60; 95%CI 1.02-2.60), public location (OR 2.10; 95%CI 1.13-3.80), exercise (OR 3.0 95%CI 1.56-5.59) and chest pain ≤24 hours prior (OR 2.90 95%CI 1.30-6.42). Conclusion: Many young SCDs have previously diagnosed cardiac RFs and acute symptoms suggestive of ischemia prior to their event. These findings highlight the potential value of better public awareness in the younger age group for signs and symptoms of ischemia and potential risk for SCD.