Primary success of electrical cardioversion for new-onset atrial fibrillation and its association with clinical course in non-cardiac critically ill patients: sub-analysis of a multicenter observational study

BACKGROUND: Electrical cardioversion (ECV) is widely used to restore sinus rhythm in critically ill adult patients with atrial fibrillation, although its prognostic value is uncertain. This study aims to elucidate the clinical meaning of successful ECV. METHODS: This is a sub-analysis of the AFTER-ICU study, a multicenter prospective study with a cohort of 423 adult non-cardiac patients with new-onset atrial fibrillation (AF). Patients that underwent ECV within 7 days after initial onset of AF were included in the sub-analysis. We compared intensive care unit (ICU) and overall hospital mortality, survival time within 30 days, cardiac rhythm at ICU discharge, and the length of ICU and overall hospital stay between patients whose sinus rhythm was restored immediately after the first ECV session (primary success group) and those in whom it was not restored (unsuccessful group). To find the factors related to the primary success of ECV, we also compared patient characteristics, the delivered energy, and pretreatment. RESULTS: Sixty-five patients received ECV and were included in this study. Although 35 patients (54%) had primary success, recurrence of AF occurred in 24 of these patients (69%). At ICU discharge, three patients still had AF in the unsuccessful group, but no patients in the primary success group still had AF. ICU mortality was 34% in the primary success group and 17% in the unsuccessful group (P = 0.10). Survival time within 30 days did not differ between the groups. Delivered energy and pretreatment were not associated with primary success of ECV. CONCLUSIONS: The primary success rate of ECV for new-onset AF in adult non-cardiac ICU population was low, and even if it succeeded, the subsequent recurrence rate was high. Primary success of ECV did not affect the rate of mortality. Pretreatment and delivered energy were not associated with the primary success of ECV. TRIAL REGISTRATION: UMIN clinical trial registry, the Japanese clinical trial registry (registration number: UMIN000026401, March 31, 2017). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40560-021-00562-8.