Step forward in gene therapy to treat cause of sudden cardiac arrest in athletes

People with arrhythmogenic cardiomyopathy are born with normal hearts but begin to develop an irregular heartbeat in their 20s or 30s. These arrhythmias can raise the heart rate to dangerous levels and explain why some individuals with the condition experience sudden cardiac arrest during exercise.

Scientists have corrected abnormal heart rhythms in mice by restoring healthy levels of a protein that heart cells need to establish connections with one another. That protein, GJA1-20k, is underproduced in people with a genetic condition called arrhythmogenic cardiomyopathy, one of the leading causes of sudden cardiac arrest in athletes under the age of 35.

The finding, reported in the journal Circulation Research, suggests a new strategy for treating the abnormal heart rhythms caused by arrhythmogenic cardiomyopathy. The results may also have implications for treating dangerous arrhythmias associated with more common conditions, such as those that can develop soon after a heart attack.

To determine if they could restore the heart’s normal rhythm, the scientists turned to mice that have similarities to people with arrhythmogenic cardiomyopathy. They both have low levels of GJA1-20k and develop arrhythmias. The researchers used low doses of gene therapy to bring the trafficking protein back to normal levels. This, they confirmed, enabled heart muscle cells to transport Connexin 43 to its proper locations.

Most importantly, it gave the animals a more normal heartbeat. “The ease and low dose needed to fix the arrhythmias of even an inherited heart disease suggests that the authors have identified a critical pathway to stabilize cardiac electrical activity.

Disruptions in protein trafficking are thought to contribute to arrhythmias beyond those caused by arrhythmogenic cardiomyopathy, and authors are optimistic that a similar treatment strategy might be useful for those conditions, too.

Reference:

Step forward in gene therapy to treat cause of sudden cardiac arrest in athlete; Circulation Research; DOI: 10.1161/CIRCRESAHA.122.322294