Major advances in cardiac medicine have significantly increased the life expectancy of patients with congenital heart defects. More than 90 percent of patients with congenital heart defects now reach adulthood, even those with severe defects. However, unlike people with healthy hearts, they need regular, lifelong specialist monitoring and follow-up care.

If detected too late, secondary diseases and complications can significantly reduce life expectancy and quality of life. "In the long term, the development of heart failure and sudden cardiac death are among the major risks. This is especially true for patients with a systemic right ventricle," says Corinna Lebherz, ACHD cardiologist and senior physician at the Department of Cardiology, Angiology and Internal Intensive Care at RWTH Aachen University Hospital.

When the Right Ventricle Takes Over

Our heart is the crucial engine for the vital interaction between the lung circulation and body circulation. In a healthy heart, oxygen-poor blood is pumped at low pressure from the right ventricle to the lungs, where it is enriched with oxygen. The muscular left ventricle pumps the oxygen-rich blood from the lungs at a higher pressure from the left ventricle into the systemic circulation, supplying all the organs.

The situation is different in transposition of the great arteries (TGA). If this is corrected by atrial inversion surgery, the right ventricle takes over the function of the left ventricle. This is also the case in the rare condition known as congenitally corrected TGA (ccTGA), in which the ventricles are reversed. Doctors therefore refer to both cases as 'systemic right ventricle'. 

Heart Failure is a Common Late Effect

However, unlike the left ventricle, the muscles of the right ventricle are not designed for the strenuous pumping action required to supply blood to the entire body. This significantly increases the risk of dying due to late complications, explains ACHD cardiologist Corinna Lebherz.

"The right ventricle gains muscle mass. This means that it can initially cope with the increased workload. In the long term, however, the muscles often stiffen. The ventricle dilates and the heart can no longer pump well. This is often accompagnied by the tricuspid valve, the inlet valve of the right ventricle, no longer opening or closing properly. These changes also increase the risk of arrhythmias. If left untreated, it can lead to cardiac arrest," says the senior physician.

Minimizing the Risks

The need for drug treatment of heart failure is obvious. But there is a catch: "The benefits of appropriate medication for patients with reduced left ventricular function are well documented. However, there is a lack of comparable studies for patients with systemic right ventricular dysfunction. This may mean that drug therapy for the latter is too rarely considered and discussed. The benefits and risks must be weighed up individually," says Corinna Lebherz.

In a nationwide study, she and her colleagues analyzed the care situation of patients with systemic right ventricular failure after atrial inversion surgery or congenitally corrected TGA in Germany: "We wanted to know how many patients were diagnosed with congestive heart failure and how many of them were treated with drug therapy".

Progression After Atrial Switch Surgery and with ccTGA

To this end, the researchers retrospectively analyzed the disease progression of a total of 380 participants in the National Registry. The team analyzed the medical data of 285 patients with TGA after atrial switch surgery and 95 patients with congenitally corrected transposition of the great arteries. The data was collected between 2008 and 2018, and the average age of the patients was 33 years.

Limited Pump Function in Every Third to Fourth Patients

"It turned out that the pumping function of the right ventricle was described as moderately or severely impaired in more than a quarter of patients (25.5 per cent) after atrial switch surgery and in more than a third of patients with congenitally corrected transposition (35.1 per cent)," says Corinna Lebherz. "However, the use of cardiovascular drugs to treat heart failure was very rare".

Getting Better at Treating Heart Failure in ACHD in the future?

Should the results of the study be worrying? "Not necessarily. The result could also be related to the period in which the data were collected. Awareness of the benefits of drug treatment has increased significantly since then," says Corinna Lebherz. "In the meantime, new promising drugs have been approved in the form of so-called SGLT2 inhibitors. The European Society of Cardiology has adapted its guidelines for the treatment of heart failure accordingly," says the ACHD cardiologist.

The drugs are expected to be increasingly used in adults with congenital heart defects, where the right ventricle takes over the functions of the left ventricle. Initial studies in this group of patients are also encouraging. "Further randomised, controlled trials are definitely needed," says Corinna Lebherz.

Individual Risk-Benefit Assessment

The researchers strongly recommend regular specialist follow-up. In the presence of a systemic right ventricle associated with symptoms or signs of heart failure, the initiation of appropriate drug therapy should be discussed. It remains important to weigh up the risks and benefits of medication on an individual basis. The decision should be made together with the patient.