The most dreaded complications of myotonic dystrophy (DM) involve the cardiopulmonary system, which can present in upwards of fifty percent of patients. These take form in cardiomyopathies, conduction system and rhythm defects, and early-onset heart failure due to progressive cardiac tissue reconstruction. Arrhythmias remain the second most common etiology of death in this population. While definitive diagnosis relies on genetic analysis and identification of the detrimental CTG trinucleotide repeat sequences, clinicians can utilize a thorough history and clinical exam to anticipate, recognize, and manage systemic sequela.
A 46-year-old woman with history of DM, left bundle branch block, QTc prolongation, obesity, and prior deep vein thrombosis in pregnancy was admitted after an out-of-hospital cardiac arrest. There was a strong family history of DM which affected her mother and claimed her two children through sudden cardiac death, with her daughter passing days prior to the current presentation. She was down for forty-five minutes and without CPR for at least fifteen minutes. Initial rhythms were ventricular tachycardia and ventricular fibrillation. She arrived at our facility intubated, hemodynamically unstable requiring multiple vasopressor support, and started on targeted temperature management. Within the first few days, she was quickly weaned to two vasopressors and started making small purposeful movements with MRI showing no signs of anoxic brain injury. Despite multiple course complications, she showed signs of slow neurologic recovery but ultimately required tracheostomy and PEG tube placement. Several months later, a biventricular intracardiac cardioverter-defibrillator was implanted for secondary prevention and she continues to progress on her road to recovery in a rehabilitation facility.
Despite high risk of cardiac arrhythmia and sudden cardiac death, current recommendations for primary prevention in DM have not been entirely delineated in the absence of cardiac abnormalities on invasive or non-invasive testing modalities. Patients should undergo regular screening with both ECG and echocardiography for risk stratification and monitoring of cardiac involvement. While individual disease progression is variable, there should be a push to better assess and identify patients most at-risk for development of severe cardiac involvement and protect them from the arrhythmias that claim at least one third of their lives.