Conundrum of Sudden Cardiac Death
Making Sense of Missense
The cause of sudden cardiac death (SCD) in a young patient without any previous cardiac history can oftentimes be challenging, particularly if there are ≥2 equally plausible but improbable pathogenesis. As part of a thorough evaluation, electrophysiological, anatomic/functional, and genetic testing results may be illuminating but at other times can be misleading unless the nuances of test results and their interpretation are fully appreciated. We report a case of a patient who survived an out-of-hospital cardiac arrest after vigorous exercise and who was found to have a decrementally conducting Mahaim-like accessory pathway (AP), as well as a dilated right ventricle (RV) and a missense mutation identified in the plakophilin-2 (PKP2) gene. We examine the challenges of interpreting results of such screening tests and how to distinguish the probable pathogenesis of SCD when there are 2 competing findings, neither of which is entirely dispositive.
A 29-year-old white woman with multiple congenital anomalies, including coarctation of the aorta and bicuspid aortic valve, was admitted to the hospital after sudden cardiac arrest. Several years earlier, she was reported to have a transient irregular wide complex tachycardia thought to be because of preexcited atrial fibrillation (AF). On the day of presentation, she experienced abrupt syncope immediately after playing tennis. A bystander initiated cardiopulmonary resuscitation and delivered 2 shocks with an automatic external defibrillator (Figure 1). Emergency medical services arrived shortly afterward and delivered an additional external shock, resulting in a return of spontaneous circulation. Rhythm strips shortly after resuscitation showed an irregular rhythm with a narrow complex configuration and runs of an irregular rhythm with a wide complex morphology. She was brought to her local emergency room where her initial laboratory studies were all within normal limits. A toxicology screen was negative. A 12-lead ECG showed sinus bradycardia at 38 beats per minute with …