Long term risk of recurrence among survivors of sudden cardiac arrest: A systematic review and meta-analysis.

AIMS

With a growing number of survivors of sudden cardiac arrest globally, their natural disease progression is of interest. This systematic review and meta-analysis aimed to determine the risk of recurrence after sudden cardiac arrest and its associated risk factors.

METHODS

Medline, Embase, Cochrane Library and Scopus were searched from inception to October 2021. Studies involving survivors of an out-of-hospital sudden cardiac arrest event of any non-traumatic aetiology were included. Meta-analyses of proportions using the random-effects model estimated the primary outcome of first recurrent sudden cardiac arrest incidence as well as secondary outcomes including cumulative incidence of recurrence at 1-year and incidence of second recurrence among survivors of first recurrence. A recurrent episode was defined as a sudden cardiac arrest that occurs 28 or more days after the index event. Subgroup and meta-regression analyses were conducted for predetermined variables. The Newcastle-Ottawa Scale was used to assess risk of bias for most studies.

RESULTS

35 studies of moderate to high quality comprising a total of 7186 survivors were analysed. The pooled incidence of first recurrence was 15.24% (32 studies; 95%CI, 11.01-19.95; mean follow-up time, 41.3 ± 29.3 months) and second recurrence was 35.03% (3 studies; 95%CI, 19.65-51.93; mean follow-up time, 161.1 ± 54.3 months). At 1-year, incidence of recurrence was 10.62% (3 studies; 95%CI, 0.25-30.42). Subgroup analyses found no significant difference (p = 0.204) between incidence of first recurrence published from 1975-1992 and 1993-2021, and between studies with mean follow-up time of <24 months, 24-48 months, and >48 months. On meta-regression, initial shockable rhythm increased incidence of first recurrence (p = 0.01).

CONCLUSION

15.24% of sudden cardiac arrest survivors experienced a recurrence, and of these, 35.03% experienced a second recurrence. Most recurrences occurred in the first year. Initial shockable rhythm increased this risk. Despite the limitations of inter-study heterogeneity, these findings can still guide intervention and follow-up of sudden cardiac arrest survivors.