High Mortality in Patients With an Atrial Septal Defect vs the General Population

Patients with an atrial septal defect (ASD) have a higher overall mortality compared with the general population, although this increased mortality is not observed if the defect is closed prior to 30 years of age, according to the results of a nationwide retrospective cohort study conducted in Finland and published in the Journal of the American Heart Association.

The investigators aimed to evaluate long-term mortality and cause-specific mortality of patients with ASD. They sought to report new data on the causes of death in patients with ASD and to identify areas in need of particular consideration moving forward. The data that support the study findings are available from Statistics Finland and the Finnish Hospital Discharge Register (FHDR).

For each patient with ASD being evaluated, 5 controls from the general population were matched with respect to sex, age, and residence (city or municipality) at the index date. The index date was defined as “the date of closure and date of diagnosis for patients with unclosed ASD.” All patients diagnosed with simple ASD in the hospital discharge registry from 1969 to 2019 were included in the analysis. Complex congenital defects were excluded from the study and median follow-up was 11.1 years (range, 0-51 years).

Following exclusion, a total of 9084 patients were included in the study. The rate of ASD diagnosis began to escalate between 1990 and 2000. Follow-up data were available for 99.3% of the patients. Overall there were 131,003 patient-years.

Patients with ASD had more baseline comorbidities at the time of diagnosis compared with the control group. ASD closure was performed in 2281 individuals between 1986 and 2019 (mean patient age, 30.8 years; range, 0-84 years). Among these individuals, 1472 received a surgical closure and 856 had a transcatheter closure.

Results of the study showed that patients with ASD had higher overall mortality than controls (adjusted mortality risk ratio [MRR], 1.72; 95% CI, 1.61-1.83). MRRs for women were 1.79 (95% CI, 1.65-1.94) and 1.64 (95% CI, 1.48-1.81) for men.

Additionally, patients with closed ASDs had higher total mortality (MRR, 1.29; 95% CI, 1.10-1.51). No difference in mortality was detected, however, if the defect was closed prior to the age of 30 years (MMR, 1.58; 95% CI, 0.90-2.77). In those with surgically closed defects, the MMR was 1.49 (95% CI, 1.26-1.76).

Individuals with transcatheter-closed defects had lower mortality than those in the control group (MRR, 0.65; 95% CI, 0.42-0.99). Further, lower mortality was observed in these patients compared with those with surgically closed defects (MRR, 0.37;
95% CI, 0.23-0.59).

Overall, 1271 deaths were reported in the ASD population. There were 98 deaths by age 30 years and 202 deaths reported by age 50 years in the patient group. This was the equivalent of a cumulative mortality risk of 1.1% at 30 years of age and 2.2% at 50 years of age. In the control cohort, the cumulative mortality risks at 30 years of age and 50 years of age were 0.2% and 0.7%, respectively. In 5 patients the 30-day mortality following closure was 0.2%, with each event occurring after the surgical closure.

Patients with ASD experienced significantly more deaths due to the following:

• Congenital malformations (MRR, 54.61; 95% CI, 34.03-87.64)
• Other diseases of the circulatory system (MRR, 2.90; 95% CI, 2.42-3.49)
• Stroke (MRR, 1.89; 95% CI, 1.52-2.33)
• Diseases of the endocrine system (MRR, 1.88; 95% CI, 1.10-3.22)
• Diseases of the respiratory system (MRR, 1.71; 95% CI, 1.19-2.45)
• Ischemic heart disease (MRR, 1.62; 95% CI, 1.41-1.86)
• Accidents (MRR, 1.41; 95% CI, 1.05-1.89)

As the study was retrospective in design, despite the FHDR reportedly being accurate, the potential for coding misclassifications cannot be excluded. Also, some selection bias exists among patients born prior to 1969, since individuals with more severe defects may have died prior to the start of follow-up. Also, the closure rate for patients with ASD in the entire cohort is unknown, with procedural codes included in the discharge registry only after 1986.

“Higher cause-specific mortality was seen in congenital abnormalities, stroke, and heart diseases,” the study authors wrote. “Patients applicable for transcatheter closure have an excellent prognosis.”