Abstract 12846: Age-specific Difference in the Prognostic Significance of Conversion From Nonshockable to Shockable Rhythm in Out-of-hospital Cardiac Arrest: a Prospective Nationwide Population-based Cohort Study in Japan

Abstract

Introduction: Early defibrillation in out-of-hospital cardiac arrest (OHCA) patients with conversion from nonshockable to shockable rhythms is associated with favorable neurological outcomes. Hypothesis: We hypothesized that the prognostic significance of subsequent shock delivery would differ according to age and the time from initiation of cardiopulmonary resuscitation by emergency medical service providers to the first defibrillation (shock delivery time). Methods: We analyzed the records of 219,528 adult OHCA patients with initial nonshockable rhythm. Data were obtained from a prospectively recorded Japanese national Utstein-style database from 2011 to 2012. The primary end point was 1-month survival with favorable neurological outcomes (cerebral performance category scale, category 1 or 2; CPC 1-2). Results: The rates of 1 month CPC 1-2 were 1.7% (127 of 7391) in patients with subsequent shock and 0.7% (1530 of 212,137) in those without subsequent shock (p < 0.001). When sorted by age, the rates of subsequent shock delivery were 4.4% (1945 of 44,602), 4.1% (1514 of 36,584), 3.1% (2137 of 69,278), 2.6% (1550 of 58,614), and 2.3% (245 of 10,450), and the rates of 1 month CPC 1-2 in patients with subsequently shocked OHCA were 3.7% (71 of 1945), 2.1% (32 of 1514), 0.8% (18 of 2137), 0.4% (6 of 1550), and 0% (0 of 245), for patients aged 18-64, 65-74, 75-84, 85-94, and ≥95 years, respectively (p for trend <0.001, respectively). Multivariate logistic regression analysis revealed that subsequent shock delivery was positively associated with 1-month CPC 1-2: adjusted odds ratio (aOR) 6.9 (95% confidence interval, CI: 3.5-12.6) for shock delivery times <10 min and 3.4 (2.4-4.7) for 10-19 min in patients aged 18-64 years, and 4.0 (1.4-9.4) for <10 min in patients aged 65-74 years. However, subsequent shock delivery was negatively associated with 1-month CPC 1-2 in patients aged 85-94 years for 20-59 min: aOR 0.2 (95% CI 0.0-0.7). Moreover, subsequent shock delivery was not associated with the 1-month outcomes in OHCA patients aged 75-84 years. Conclusions: After rhythm conversion from initial nonshockable to shockable rhythms, early defibrillation was associated with increased odds of 1-month CPC 1-2 in OHCA patients not aged ≥75 years but aged 18-74 years.