Congenital heart disease (CHD) is the most common congenital malformation, with an incidence of 1% of all live births. It is thirty times more common than cystic fibrosis and fifty times more frequent than pediatric cancer. Over the past 70 years, CHD has transformed from a fatal diagnosis to one where more than 97% of diagnosed individuals reach adulthood. This revolutionary change in treatment has led to a situation in many countries where adults with congenital heart disease (ACHD) now outnumber children with CHD. These advancements are largely due to continuous technological progress and the perseverance of the medical community. Special recognition goes to Helen Taussig and Maude Abbott, the pioneering cardiologists who first studied and treated CHD.

This study provides a retrospective analysis of the impact of this revolution in Sweden. Researchers reviewed various national databases of inpatient, outpatient, and mortality records. The analysis included all individuals with CHD born between 1950 and 1999 who survived beyond 18 years of age. For every CHD patient, ten matched controls were selected from the same databases. Follow-up was conducted from 1968 to 2017, tracking all adults until death. Patients who died before 18 years of age were excluded. The primary aim was to assess the mortality and cardiovascular morbidity of ACHD patients during adulthood in Sweden.

Given the heterogeneity of this population, patients were categorized into six groups (following methodologies from similar studies):

• Group 1: Conotruncal defects (e.g., truncus arteriosus, transposition of the great arteries, double-outlet right ventricle, aorto-pulmonary window, tetralogy of Fallot).
• Group 2: Severe non-conotruncal defects (e.g., single ventricle, hypoplastic left heart syndrome, atrioventricular canal defects).
• Group 3: Coarctation of the aorta.
• Group 4: Ventricular septal defect.
• Group 5: Atrial septal defect.
• Group 6: Miscellaneous defects not classified into the above groups.

A total of 37,278 ACHD patients were included and compared with 412,799 controls. The average follow-up period was 19.2 years. During this time, 1,937 ACHD patients (5.2%) and 6,690 controls (1.6%) died, resulting in mortality rates of 2.73 and 0.84 per 1,000 person-years, respectively. Mortality among ACHD patients was 3.2 times higher (p < .001) compared with controls. After up to 50 years of follow-up, over 75% of ACHD patients were still alive, and 75% reached the age of 60 years. Mortality consistently declined over time (p < .001), with the decline beginning in the 1970s. Adjusted mortality was elevated across all groups (p < .001), with the highest hazard ratio (HR: 10.03) observed in conotruncal anomalies, followed by severe non-conotruncal defects (HR: 7.36). Even conditions traditionally considered “curative,” such as atrial septal defect, showed a slightly elevated mortality (HR: 1.36).

The authors concluded that ACHD patients had more than three times the mortality risk of individuals without CHD. Despite this, 75% of ACHD patients who survived to age 18 reached their sixth decade of life. Patients born after 1975 experienced a lower subsequent mortality risk.

COMMENTARY:

What is CHD? It is an abnormality of one or more cardiac or vascular structures present at birth. Achieving a complete, closed, and dual circulatory system has required millions of years of evolution. Unlike the left ventricle, which has undergone natural selection since the Devonian period 500 million years ago, the right ventricle only emerged 180 million years ago during the Jurassic period. The need for continuous terrestrial respiration demanded an auxiliary circulatory pump to direct blood flow to the lungs, leading to the development of the subarterial conal free wall and the septation of systemic and pulmonary circulations. These evolutionary changes are highly complex, making it unsurprising that occasional errors still appear in the developmental “symphony” of the cardiovascular system.

The need to address these anomalies gave birth to the specialty of congenital heart disease. Soon, the number of adults with CHD (ACHD) will surpass the number of children with CHD in Spain. As Lady Somerville predicted in her Lancet article more than 40 years ago, “we expect a tsunami of ACHD” in the coming decades.

The successes of previous generations in CHD management have led to a growing cohort of ACHD patients. In the years to come, colleagues from various specialties will face these patients, either directly or indirectly, requiring specialized care. In cardiology, ACHD patients present with arrhythmic, vascular, and valvular complications, complex management of pulmonary hypertension and residual shunts, and most notably, advanced heart failure. For this reason, it is essential to care for this population in specialized CHD centers to ensure proper management.

No study comes without limitations. While this study analyzes outcomes from nearly 9 million patient-years with minimal loss to follow-up, it relies on administrative records. The results depend on accurate coding of morbidity, mortality, and patient diagnoses. The study lacks access to clinical data, which limits insight into disease progression and terminal events. Additionally, some conditions share a single code (e.g., atrial septal defect and patent foramen ovale), complicating the interpretation of results. Furthermore, technological advancements, such as the routine use of echocardiography, have likely identified patients with simpler defects who were previously undiagnosed, making comparisons across time periods challenging. These data must be interpreted cautiously, as demographic analyses of ACHD patients may oversimplify the complexity of these conditions.

In conclusion, CHD has undergone a revolution over the past century, transforming from an incurable disease to a chronic condition. Studies like that of Dellborg et al. demonstrate that while significant progress has been made, there is still work to do to improve outcomes that are already remarkable.

REFERENCE:

Dellborg M, Giang KW, Eriksson P, Liden H, Fedchenko M, Ahnfelt A, el al. Adults With Congenital Heart Disease: Trends in Event-Free Survival Past Middle Age. Circulation. 2022 Dec 26. doi: 10.1161/CIRCULATIONAHA.122.060834.