It is a tremendous advance in cardiac medicine research: more than 90 percent of people with congenital heart defects reach adulthood. One in one hundred children is born with the most common congenital malformation. Thanks to improved surgical and interventional procedures, even severe heart malformations can be treated well today. As a result, the number of adults with congenital heart defects is steadily increasing. According to estimates, the group of adults with congenital heart defects is growing by five percent a year. Adult patients already account for more than two-thirds of all those affected.

A Congenital Heart Defect Remains

But most of them are not cured. Particularly in the case of moderate or severe heart defects, the risk of dying prematurely from heart failure, cardiac arrhythmias, infective endocarditis or because of follow-up surgery is high. Research in this field, which is still young, is therefore increasingly focused on answering questions about the optimal way to provide care, the best treatment options for residual complications, and risk assessment for adverse outcomes.

Research Under Difficult Conditions

For reliable results, researchers depend on a broad data base. And this is precisely the crux of the matter, as the chairman of the Competence Network for Congenital Heart Defects, Professor Anselm Uebing, explains: "In the case of congenital heart defects, we are dealing with a large number of diagnoses that are rare in themselves. The clinical pictures range from simple ventricular septal defects to complex malformations such as single ventricle. Some are associated with other organ malformations and cause extracardiac concomitant diseases. Each patient has their own unique medical history with surgeries and procedures, sequelae, complications, or interactions with other age-related conditions. Accordingly, it is difficult to obtain sufficient data for meaningful study results."

Evidence Gap with Consequences

Yet there have long been large multicenter registries that provide such research bases, such as the National Registry for Congenital Heart Defects. For more than twenty years, this internationally renowned research institution has been collecting voluntarily donated medical data from patients with congenital heart defects and preparing it for research. More than 50,000 children and adults support international research in this way. The biobank of the National Registry has biomaterial from more than 10,000 patients.

"The registry at the Competence Network is a unique research base worldwide. However, the maintenance of such structures of patient-oriented research in our special field is still not financed and promoted sustainably enough. As a result, science in the field of congenital heart defects is sometimes forced to lag behind the progress it has made possible," notes Professor Anselm Uebing. This has consequences: "Less than one percent of all recommendations for the therapy regime for patients with congenital heart defects are based on data from controlled studies. This evidence gap is of increasing concern to us," says the pediatric cardiologist.

Research Cooperation with the Health Insurance Funds

In addition, it would be crucial to be able to perform comparative analyses that also take the general population into account in order to provide the best possible care for patients well into old age. Great hopes are now being placed in the use of Big Data and artificial intelligence for corresponding long-term studies on a broad data basis, for example also with the systematically collected care data from health insurance companies.

The importance of such new avenues in research is also demonstrated by the latest in a series of study results from the research group led by ACHD specialist Professor Gerhard-Paul Diller from Münster, which the European Heart Journal has published over the past two years.

Alarming Result

The recently published study based on data from the Barmer health insurance fund has shown that an immune deficiency in congenital heart defects is more common than previously assumed. For this purpose, the researchers were able to access medical data from more than 50,000 insured persons with congenital heart defects and compare them with those of corresponding cohorts without congenital heart defects from the group of around 9 million insured persons in total.

"We are familiar with immunodeficiencies from genetic syndromal disorders such as DiGeorge syndrome, Down syndrome or CHARGE syndrome. The fact that the risk of this across the entire spectrum of congenital heart defects is significantly higher than in people without congenital heart defects is new and has surprised us. Most importantly, the study shows that immunodeficiency is a clear risk factor for emergency hospitalization and early death," emphasizes Professor Marc-Phillip Hitz, a human geneticist and pediatrician specialized in structural heart disease. "This illustrates once again how crucial both highly specialized follow-up care for congenital heart defects and multidisciplinary collaboration, in this case with immunologists, are."

Deeper Research Is a Must

The findings of such studies help improve healthcare and patient management in patients with congenital heart defects. They also provide important clues for further research: "The immunodeficiencies diagnosed in 5.6 percent of patients may have a common genetic cause with congenital heart defects. It is conceivable that certain changes in the genes are responsible for both the impairment of the immune cells and the maldevelopment of the heart," explains Professor Marc-Phillip Hitz.

He also says it cannot be ruled out that removal of the thymus, which is usually part of neonatal  heart surgery for congenital heart defects, contributes to altered immune function. "We urgently need to know something like this more precisely in order to be able to counteract it therapeutically."

No Progress in Therapy Without Interaction with Registry Research

To do this, however, the scientists need more detailed data than is available to the health insurance companies. "Without phenotypically well-described patient cohorts, detailed information on the respective clinical course, for example on infectious episodes, symptoms, the sequence and type of interventions, concomitant diseases or blood findings, and without access to biomaterial for molecular biology research, we will not make any progress," says the human geneticist. That remains the task of multicenter registries and biobanks.

In the future, the intelligent interaction of research with the broad data sets of health insurance companies and multicenter registry research will be crucial for the quality of life and prognosis of more and more people. What is at stake is evidence-based patient care and thus a great deal.

Further press materials

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