Outcomes of out-of-hospital cardiac arrest in ACHD

A recent study published in the European Heart Journal addressed the outcomes of out-of-hospital cardiac arrest in adult congenital heart disease. This was a registry-based study from Denmark.

Congenital heart disease (CHD) epidemiology has undergone significant changes due to advancements in diagnostic and therapeutic procedures. CHD is associated with higher morbidity and mortality compared to the general population, with severe CHD posing the greatest risk. Sudden cardiac death (SCD) accounts for up to 25% of CHD-related deaths and is attributed to various mechanisms, including arrhythmias, myocardial ischemia, heart failure, and aortic pathologies. In Europe, around 250,000 SCDs and 350,000 out-of-hospital cardiac arrests (OHCAs) occur annually, with low survival rates (around 10%), making OHCA the third leading cause of death in Europe. However, research on the association between CHD and OHCA is limited, characterized by small studies, heterogeneity in CHD classification, and tertiary care center bias. This study aimed to investigate the rate of CHD-associated OHCA, the influence of various factors on this association, pre-hospital OHCA characteristics' effect on post-OHCA outcomes, and the differences in 30-day survival between CHD and non-CHD patients.

In this study, data were collected from various Danish nationwide registries. The Danish Cardiac Arrest Registry, established in 2001, provided information on all OHCAs in Denmark. Patients with a cardiac arrest who received resuscitation attempts were included, while those with obvious signs of death were excluded. OHCA cases were classified as presumed cardiac or non-cardiac causes based on diagnosis codes from discharge diagnoses and death certificates. Data linkage was made possible through a personal registration number, allowing the combination of information from different registries. Hospital admission, surgical procedures, prescribed drugs, and causes of death were obtained from the Danish National Patient Registry, the National Prescription Registry, and the Danish Register of Causes of Death, respectively. To study the association between OHCA and CHD, a nested case-control study was conducted, focusing on patients between 18 and 90 years old with OHCA of presumed cardiac cause. CHD diagnoses were identified using hospital contacts prior to OHCA. Covariates such as ischaemic heart disease, congestive heart failure, cardiovascular risk factors, and major extracardiac organ dysfunction were considered in the analysis.

The study included a total of 43,967 cases and 219,772 controls. The median age of the participants was 72 years, and 68.2% were male. Among the cases, 105 (0.3%) had simple CHD, 144 (0.3%) had moderate CHD, and 53 (0.1%) had severe CHD. Patients with severe CHD were the youngest group and had a lower burden of comorbidity compared to patients with simple or moderate CHD. The presence of any type of CHD was associated with higher rates of OHCA compared to the absence of CHD, with increasing severity of CHD showing a trend of higher hazard ratios (HRs). Stratified analyses by age showed that moderate and severe CHD were associated with increased OHCA rates mainly in younger age categories. The crude 30-day survival rate was higher for patients with CHD compared to those without CHD, but after adjustment, the likelihood of 30-day survival was similar between the groups. Both CHD and non-CHD patients showed an increase in survival rates over the years following OHCA.