Doug Darden, MD, discusses his session from Heart Rhythm 2023.

Transcripts:

I’m Doug Darden. I’m a cardiac electrophysiologist with Kansas City Heart Rhythm Institute. We presented a case entitled “Exercise-Induced Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC): Reverse Remodeling With Detraining,” which was part of a session entitled “Best of Heart Rhythm Case Reports for 2022.” Our patient was a 25-year-old who presented to his primary care physician with premature ventricular contractions (PVCs). He had no red flag symptoms. He had no family history of cardiac issues, sudden cardiac death (SCD), or unexplained cardiac death. He went in for an evaluation, and his echocardiogram demonstrated that he did have right ventricular (RV) enlargement that prompted cardiac magnetic resonance imaging (MRI), which also showed he had moderate RV enlargement with an aneurysm formation of the basal/mid-section. We also had mild left ventricular (LV) enlargement in a mildly depressed LV ejection fraction of 49%. When we looked at his exercise history, he was a long-term endurance athlete who participated in multiple marathons and ultra-marathons. He was training to cross the Pacific Crest Trail. To calculate his total dose of exercise, it would be at least 10-14 hours of endurance training per week for over a decade. Also, his electrocardiogram demonstrated that he had a terminal deflection in V1/V2 greater than 55 milliseconds without a right bundle and he had greater than 500 PVCs in a 24-hour period. So, he fit a major or definite diagnosis of ARVC based off 1 major and 2 minor criteria, so we were left with this diagnosis of ARVC. We ended up getting a genetic panel that came out to be completely negative. He had no desmosome mutation associated with ARVC, so that left us with a few questions. Does he actually have familial ARVC? Does he need an implantable cardioverter-defibrillator? How do we risk stratify him further? After much discussion, we brought him in for an invasive electrophysiological study with voltage mapping with a high-definition mapping catheter. On the ventricular stimulation protocol, he had no ventricular tachycardia or ventricular fibrillation induced with aggressive triple extrastimuli. He then ended up having significant low-voltage areas in the basal aspect of his RV, up into his RV outflow tract. His previous MRI showed no delayed gadolinium enhancement. This left us with a diagnosis of exercise-induced ARVC, genotype negative. At this point, we asked him to detrain to help sort out this diagnosis. He followed this recommendation, only participating in low-intensity sports. We followed his MRI over a 3-year period and he had complete normalization—his LV and RV completely normalized.

The diagnosis of exercise-induced ARVC was first described in the early 2000s, showing that athletes who end up having a negative genetic mutation panel may have significant RV involvement leading to RV enlargement and ventricular arrhythmias. A subset of these patients ends up having SCD. This case highlighted the invasive EP study for risk stratification. It also highlighted the impact of detraining on this single patient and the complete normalization of his LV and RV enlargements. So, whether that reduces his risk of SCD or what his true risk of SCD is still, we do not know since it based off one patient. However, it does highlight the impact of exercise on this specific form of exercise-induced ARVC.