Life-threatening bradycardias in COVID-19 patients whilst supported on venous-venous ECMO

ABSTRACT

Background: Veno-venous extracorporeal membrane oxygenation (VV-ECMO) was increasingly used during the Coronavirus Disease 2019 (COVID-19) pandemic. COVID-19 has been associated with bradycardia however, causative mechanisms are unclear. We aimed to assess the incidence and impact of bradycardia in COVID-19 patients whilst on VV-ECMO. Method(s) Retrospective, single centre cohort study including 173 patients on VV-ECMO due to COVID 19 from Mach 2020 to March 2022. Patients with HR<60bpm were compared with non-bradycardic patients. Furthermore, bradycardic patients were divided into 3 subgroups. Groups 1 and 2 had a HR 40-60bpm, but only Group 2 received management for bradycardia;Group 3 had life-threatening bradycardia (HR<=40). Patient characteristics, clinical and laboratory findings, and patient outcomes were collected and analysed. Result(s) 88.5% of patients developed bradycardia during VV-ECMO, of which 43% developed life-threatening bradycardia. Bradycardic patients had significantly longer ECMO runs (29 (17-46) vs 12 (7-17) days, p<0.0001) and length of hospital stay (LOHS) (47 (30-67) vs 29 (22-36) days, p=0.0007). There was no difference in mortality (p=0.7973). Counterintuitively, the non-bradycardic population were more often treated with bradycardia-inducing medications, such as beta-blockers (p=0.0220). Patients in Group 3 had significantly longer ECMO duration (37 (23- 59) days, p=0.0004) and subsequently a longer LOHS (55 (37-73) days, p=0.0033) but showed no difference in mortality (p=0.3091) compared to other subgroups. Conclusion(s) Bradycardia was associated with increased ECMO duration and LOHS, especially in the case of life-threatening bradycardia. The underlying mechanisms behind the bradycardia remain unclear, however it seems unlikely bradycardia was precipitated by bradycardia-inducing medications.