Association Between No-Flow Time, Prehospital Low-Flow Time, and Conversion to Nonshockable Rhythm in Patients With Out-of-Hospital Cardiac Arrest Presenting With Initial Shockable Rhythm: A Nationwide Prospective Study in Japan.

Abstract

Background: Out-of-hospital cardiac arrest (OHCA) with initial shockable rhythm generally has a favorable prognosis. However, the prognosis worsens when this rhythm transitions to nonshockable rhythm on hospital arrival. This study aimed to investigate the association between no-flow time (NFT), prehospital low-flow time (LFT), and the conversion to nonshockable rhythm on hospital arrival in patients with OHCA initially exhibiting shockable rhythm.

Methods: We analyzed adult patients with OHCA from the JAAM-OHCA (Japanese Association for Acute Medicine Out-of-Hospital Cardiac Arrest) registry (June 2014-December 2020) with initial shockable rhythm. The primary outcome was rhythm conversion to nonshockable on hospital arrival. Adjusted odds ratios (aORs) with 95% CIs were calculated using a logistic model to examine the associations between NFT, prehospital LFT, and rhythm conversion.

Results: Of 68 110 patients, 3720 patients were included in our analysis. On hospital arrival, 27.9% patients achieved return of spontaneous circulation, 32.8% maintained shockable rhythm, and 39.3% transitioned to nonshockable rhythm (718 to pulseless electrical activity, 744 to asystole). Median NFT was 4 minutes (interquartile range [IQR], 1-9 minutes), and median prehospital LFT was 22 minutes (IQR, 14-31 minutes). Longer NFT and prehospital LFT were associated with higher aORs of rhythm conversion: NFT (5-9 minutes: aOR, 1.38 [95% CI, 1.14-1.67]; ≥10 minutes: aOR, 1.75 [95% CI, 1.44-2.14]); and prehospital LFT (15-19 minutes: aOR, 2.56 [95% CI, 2.00-3.27]; 20-29 minutes, aOR, 4.73 [95% CI, 3.83-5.85]; ≥30 minutes, aOR, 6.85 [95% CI, 5.49-8.56]).

Conclusions: Prolonged NFT and prehospital LFT were significantly associated with rhythm conversion to nonshockable on hospital arrival in patients with OHCA with initial shockable rhythm at the scene.