Increased risk of out-of-hospital cardiac arrest in patients with congenital heart disease: a nationwide study

Abstract

Abstract Background The last four decades witnessed substantial improvements in treatment of congenital heart disease (CHD) leading to most children surviving into adulthood. Currently, the number of adults with CHD surpasses that of children. The shift in the CHD population's age composition necessitates focusing on long-term problems. A significant, but not well-investigated, issue is the risk of out-of-hospital cardiac arrest (OHCA) in adults with CHD. Purpose To investigate overall and temporal changes in the rate of OHCA associated with CHD compared with the general population. Method We conducted a nested case-control study matching all adult patients with OHCA of presumed cardiac cause between 2001 and 2015 with up to five controls from the entire Danish population on age, sex, date of OHCA and cardiac comorbidities status (at least one among ischemic heart disease, heart failure and presence of implantable cardioverter-defibrillator). Patients with CHD were identified using in- and out-patient hospital diagnoses any time prior to OHCA and divided into two mutually exclusive subgroups, either non-severe or severe CHD. The subclassification of CHD is based on a hierarchical approach previously used, where at least one severe CHD diagnosis is required to be classified as severe. We used Cox regression models to compute hazard ratios (HRs) and 95% confidence intervals (CI) of OHCA. We stratified on CHD status (non-severe, severe or control), sex and OHCA year group (2001–2008 vs 2009–2015). Results We included 35,005 OHCA cases and 175,025 controls: the median age was 72 years, 66.9% were male and 34.6% had cardiac comorbidities. In total, among cases, we identified 103 patients with non-severe CHD and 51 with severe CHD, while, among controls, 247 with non-severe CHD and 69 with severe CHD. Both non-severe and severe CHD were overall associated with higher rates of OHCA compared with the general population: HR 2.11 (95% CI, 1.68–2.66) and HR 3.93 (95% CI, 2.71–5.69), respectively (Figure A). We found similar results when we stratified the analyses according to the presence of cardiac comorbidities at date of OHCA (Figure B) and sex. When stratified by OHCA year group, we observed stable rates of OHCA associated with non-severe CHD: from HR 2.03 (95% CI, 1.36–3.03) in the period 2001–2008 to HR 2.15 (95% CI, 1.62–2.86) in the period 2009–2015. Conversely, we observed a trend towards decreasing rates of OHCA associated with severe CHD: from HR 5.04 (95% CI, 2.79–9.11) in the period 2001–2008 to HR 3.10 (95% CI, 1.80–5.19) in the period 2009–2015 Conclusions Non-severe and severe CHD were both associated with higher rates of OHCA compared with the general population. While we observed decreasing rates of OHCA over calendar year for severe CHD, they remained stable for non-severe CHD. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Gentofte University Hospital, Hellerup, Denmark