Clinical characteristics and outcomes after extracorporeal cardiopulmonary resuscitation in out-of-hospital cardiac arrest patients with an initial asystole rhythm.

Aim: This study aimed to describe the characteristics of cases of out-of-hospital cardiac arrest (OHCA) with an initial asystole rhythm in which extracorporeal cardiopulmonary resuscitation (ECPR) was introduced and discuss the clinical indications for ECPR in such patients.

Methods: This was a secondary analysis of the SAVE-J II study, a retrospective, multicentre, registry study involving 36 participating institutions in Japan. Patients with an initial asystole rhythm were selected. Favourable neurological outcomes (cerebral performance categories 1-2) constituted the primary outcome.

Results: In total, 202 patients met the inclusion criteria, with favourable neurological outcomes at hospital discharge in 12 patients (5.9%). Causes of cardiac arrest with favourable neurological outcomes were hypothermia (7 cases), acute coronary syndrome (2 cases), arrhythmia (2 cases), and pulmonary embolism (1 case). Among patients with non-hypothermia (temperature ≥32 °C) on hospital arrival with the cardiac rhythm of asystole or pulseless electrical activity (PEA) on arrival, all 107 patients (66 asystole, 41 PEA) who lacked one or more of the requirements (witness; bystander CPR; signs of life or pupil < 5 mm) had unfavourable neurological outcomes. All 5 cases with favourable neurological outcomes, except for 1 case with a short duration of no-flow time that was highly suspected based on the patient's history, met all the requirements on hospital arrival.

Conclusions: A total of 202 ECPR cases with an initial asystole rhythm, including 12 patients with favourable neurological outcomes, were described. Even if the initial cardiac rhythm is asystole, ECPR could be considered if certain conditions are met.