Early Sudden Death Following Cardioversion Of Atrial Fibrillation

Background: Direct current cardioversion (DCCV) s considered a safe procedure, but, there are reports of sudden cardiac death (SCD) following it.

Objective: We sought to study the rate and risk factors for early (30d) sudden death following DCCV.

Methods: Data of all consecutive patients undergoing first DCCV of AF between 2007 and 2016 were retrospectively reviewed. We compared all cases of SCD within 30 days of DCCV (SCD gr) with a case control group (gr) of 60 pts patients of the same cohort, matched by age and sex.

Results: 1,696 patients (48% F ) had first DCCV for AF. 15 patients (47% F) died suddenly within 30 d (median 5.9 d, range 0-30). Two patients had died while monitored and had documented VF. No differences between groups were found in heart rate prior to DCCV, cardiovascular risk factors, ischemic heart disease, prior CABG, and stroke occurrence. No difference in baseline QT interval but shorter QTc in the SCD gr {452.5±55.2 vs 479.6 ± 39.3 ms, p = 0.031} was found. In the SCD gr there was a higher incidence of new-onset (less than 24 hours) AF {53.9% vs 10%, p=0.002}, long-standing AF {40.0% vs 5.0%, p=0.002}, left ventricular dysfunction {40.0% vs. 6.8%; p=0.001}, pulmonary congestion post cardioversion {6.7% vs 0.0%, p=0.044}, and of increased postcardioversion QTc {481.3±50.8 vs 448.6 ± 40.8 ms, p = 0.012}. The change in the QTc (ΔQTc = QTc post - QTc pre cardioversion) was greater in the SCD gr {+27.2±44.3 vs -31.1±46.3 ms, p<0.0001}.

Conclusions: SCD following DCCV occurs in 0.9% of patients. Risk factors include QTc prolongation post cardioversion, new-onset AF or long standing AF, low ejection fraction, and postcardioversion pulmonary congestion. It is conceivable that maladaptation of the QT interval may play an important role in postcardioversion SCD in susceptible patients. Patients with these risk factors may benefit from longer monitoring following DCCV.