Our heart beats up to 100,000 times a day, on average 60 to 80 times a minute. During excitement, sports or heavy physical exertion, the heart temporarily beats faster. However, if the heart stumbles or races at rest, a cardiac arrhythmia is often the underlying cause.

Supraventricular tachycardia (SVT) is a rapid cardiac arrhythmia from the atria. This may be related to congenital disorders of the conduction pathway. Other possible causes, mostly in advanced age, are inadequate oxygen supply to the myocardial tissue (myocardial hypoxia), altered blood flow mechanics or reentry circuits that may form around scar tissue or patch material.

Atrial Fibrillation is Not Rare

The most common is what is known as atrial fibrillation. According to the German Heart Foundation, about 1.8 million people in Germany are affected.  Another form of supraventricular tachycardia is atrial flutter. In atrial flutter, the heartbeat is also irregular and usually accelerated. Unlike atrial fibrillation, however, atrial flutter is a rhythm disorder that usually originates from the right atrium of the heart.

Often Only Discovered by Chance and Late

As a rule, such cardiac arrhythmias typically occur at an advanced age. In people with congenital heart defects, they are among the most common late complications. Symptoms range from palpitations, heart racing to dizziness, fainting and nausea. But one in two patients has no symptoms at all. In this case cardiac arrhythmias are often then discovered by chance and late.

Even if supraventricular tachycardias are only very rarely acutely life-threatening: In the long term, they lead to an overload of the heart muscle and reduce the pumping capacity. It increases the risk of heart failure and even a stroke due to the blood clot formation. Cardiac arrhythmias therefore require urgent medical attention.

How Well Does Catheter Ablation Work?

The most successful method of treating atrial fibrillation and atrial flutter to date is catheter ablation, in which the false impulses from the pulmonary veins are stopped by means of catheters using either heat or cold. Only the heart tissue involved is specifically sclerosed and can thus no longer transmit the false impulses. But how long-lasting is the success of this treatment in congenital heart defects, how often does it have to be repeated and what exactly does it depend on? This is what Alicia Jeanette Fischer and her team, led by ACHD specialist Gerhard-Paul Diller from Münster University Hospital, investigated as part of the large OptAHF study.

With the support of BARMER GEK, the researchers were able to follow up the data of all adults with congenital heart defects who underwent a first catheter ablation for supraventricular tachycardia (SVT) over a period of three years. Data analysis included age and sex as well as the severity of the congenital heart defect and the level of specialization of the treating institution.

Specialized Treatment Increases Chances of Success

A total of 485 patients were treated for SVT by catheter ablation, almost half of them were women (49.5 percent). The average age was about 58 years. "During the three-year follow-up period, we observed a significant increase in these procedures, mostly due to atrial fibrillation, but often also due to atrial flutter. Patients of advanced age with a moderate to severe congenital heart defect were particularly affected," summarizes first author Alicia Jeanette Fischer, a specialist in internal medicine at the ACHD Center of Münster University Hospital.

Chronic kidney disease and atrial fibrillation were found to be independent predictors of recurrence. However, apart from this, it was shown that catheter ablation had to be repeated significantly less often if the primary ablation was performed in a specialized ACHD center. This was particularly striking in female patients. "Women treated in specialized centers had a 1.6-fold lower risk of having to undergo repeat treatment," said Alicia Jeanette Fischer.

Important Finding

From the researchers' point of view, the research result speaks once again in favor of specialized medical care for congenital heart defects. "This is obviously still underestimated. In this respect, we are grateful that we were able to investigate this more closely in a nationwide study with the support of the Innovation Fund of the Federal Joint Committee G-BA and BARMER. The results make a clear case for centralizing the treatment of cardiac arrhythmias in adults with congenital heart defects," says OptAHF study director Gerhard-Paul Diller.