Cardiac arrhythmia, heart failure, heart valve diseases, and vascular occlusion due to blood clots: Blood-thinning and anticoagulant drugs protect against such secondary diseases in patients with congenital heart defects. In Germany, every eighth patient with a congenital heart defect receives appropriate medication to reduce the risk of developing complications or even dying. This is the result of a current long-term study conducted by researchers of the University Hospital of Münster at the Competence Network for Congenital Heart Defects in cooperation with Barmer health insurance. But taking these medications is not without problems.

NOACs On the Rise

For a long time, congenital heart defects were mainly treated with so-called vitamin K antagonists (VKAs), which prevent the formation of certain coagulation factors in the liver. The preparations sold under the well-known trade names Warfarin® and Marcumar®, among others, require regular coagulation monitoring. Nevertheless, fatal bleeding complications can occur. The VKAs also interact with vitamin K-containing foods and various drugs.

Great hopes have therefore been placed on the new Non-Vitamin K or novel oral anticoagulants (NOACs) such as Eliquis®, Pradaxa®, Lixiana® and Xarelto®. The drugs, which have been available on the market since 2010, have fewer interactions, do not require regular coagulation monitoring, and the preparations act faster than VKAs. Since NOACs became available, their use has also steadily increased in the treatment of congenital heart defects. According to the study, NOACs already accounted for 45 percent of the anticoagulants prescribed for patients with congenital heart defects in 2018.

World's Largest Study Urges Caution with NOACs

However: Only for acquired cardiovascular diseases, recognized randomized controlled trials have so far demonstrated positive results and properties of NOACs compared to VKAs. The research group around the cardiologist and EMAH specialist Gerhard-Paul Diller, from the University Hospital Münster, in cooperation with the Barmer health insurance company, has therefore for the first time investigated the correlations between anticoagulant therapy and the long-term course in around 44,000 patients with congenital heart defects and determined the risks more precisely. The study, unique in its scope worldwide, proves that the risks associated with taking NOACs are significantly higher in patients with congenital heart defects due to their anatomical and physiological peculiarities as compared to patients with acquired heart diseases. "The use of NOACs is more problematic than long assumed," says Gerhard-Paul Diller.

Excessive Long-Term Risk

Patients with congenital heart defects who received NOACs were more likely to suffer vascular occlusion by blood clots (3.8 percent vs. 2.8 percent), bleeding (11.7 percent vs. 9.0 percent), and cardiac arrhythmia and heart failure (7.8 percent vs. 6.0 percent) during the first year of therapy compared with the control group treated with VKA preparations. The mortality rate for treatment with NOACs was also significantly higher (4.0 percent vs. 2.8 percent). A similar picture was found in the long-term observation. "In this nationwide analysis, the NOACs showed an excessive long-term risk for MACE, i.e. for major adverse cardiac events such as acute myocardial infarction, ischemic stroke, ventricular fibrillation, resuscitation, or death. This underscores the need for prospective studies before solid recommendations for their use in patients with congenital heart defects can be made," says Gerhard-Paul Diller.

Long Awaited Alternative Requires Close Monitoring

As convenient as it may seem to many patients: The fact that the coagulation status does not have to be monitored in NOACs is particularly critical in the case of congenital heart defects from the point of view of the EMAH cardiologist: "It is precisely here that it is important to recognize conspicuous features quickly in order to be able to take countermeasures in good time," says Gerhard-Paul Diller. The researchers recommend that the use of VKAs should be given greater consideration again and that AHF patients be closely monitored by experienced specialists and centers, even when NOACs are prescribed.