Factors associated with pulseless electric activity versus ventricular fibrillation: the Oregon sudden unexpected death study.

BACKGROUND: Corresponding with a continuing decline in the prevalence of sudden cardiac arrest cases presenting with ventricular fibrillation (VF), there has been a significant rise in the prevalence of pulseless electrical activity (PEA). Given significantly lower survival from PEA versus VF, we comprehensively investigated PEA correlates by incorporating first-responder data with lifetime clinical history information.

METHODS AND RESULTS: In the Portland, Ore, metropolitan area (population ≈1 million), cases of out-of-hospital sudden cardiac arrest who underwent attempted resuscitation were identified prospectively (2002-2007). Those presenting with PEA versus VF and asystole were compared with χ² tests, ANOVA, and logistic regression. A total of 1277 cases aged ≥18 years underwent resuscitation by first responders (mean age, 65±16 years; 67% male). Presenting arrhythmia was VF in 48%, PEA in 25%, and asystole/other in the remainder. Compared with VF cases, PEA cases were older (mean age, 68 versus 63 years; P=0.0002), more likely to be female (37% versus 26%; P=0.0008), and less likely to survive to hospital discharge (6% versus 25%; P<0.0001). A history of syncope was strongly associated with PEA (odds ratio, 2.6; confidence interval, 1.3 to 5.3) after adjustment for age, gender, response time, and arrest circumstances. Black race was also independently associated with PEA (odds ratio, 2.6; confidence interval, 1.3 to 5.4). Pulmonary disease and female gender were significant factors associated with PEA (P for interaction=0.04). In a subgroup analysis of resting ECGs (n=391), there were no differences in cardiac clinical history or prevalence of cardiac conduction system disease (PEA, 31.6% versus VF, 32.2%; P=0.48).

CONCLUSIONS: PEA cases had a significantly higher prevalence of syncope in their lifetime, with other correlates, including black race, that were distinct from VF cases. Potential mechanistic links between syncope and future manifestation with PEA warrant further exploration.