Figure 2. Adjudicated Causes of Resuscitated SCAs.

Etiologies of resuscitated SCAs as determined by review of EMS runsheets and hospitalization records after admission for resuscitated SCA. Causes of arrest were classified as arrhythmic (red), cardiac-nonarrhythmic (blue), and non-cardiac (green). CAD=Coronary Artery Disease.

Central Illustration. Underlying Causes of SCA By Resuscitation and Survival Status. All OHCAs between 2/1/2011 and 1/1/2015 in San Francisco County, CA were identified through EMS agencies. OHCAs dying in the field/ED (POST SCD cases) or non-sudden were excluded, to arrive at SCAs resuscitated to hospitalization. Causes of resuscitated SCA were determined after review of comprehensive hospital records: arrhythmic (red), cardiac/non-arrhythmic (blue), or non-cardiac causes (green). Arrhythmic causes accounted for 69.1% (92 of 133) of resuscitated SCAs, significantly higher than the 55.8% of SCAs resulting in WHO-defined (presumed) SCDs by autopsy as reported in POST SCD (P=0.004). Arrhythmic cause was significantly more common in survivors than non-survivors (92% vs. 57%, P< 0.001). * N=525 total presumed SCDs as previously reported,⁹ including 334 OHCAs identified in this study with initial signs of life but dying on scene/ED and an additional 191 EMS-attended cases in POST SCD without signs of life but with primary impression OHCA. † P-value survivors vs. non-survivors.