Wenckebach periodicity at rest that normalizes with tachycardia in a family with a NKX2.5 mutation.

A family with asymptomatic Wenckebach atrioventricular block (Wenckebach periodicity [WP]) has been followed at the investigators' institution for >4 decades. In contrast to all reported cases of WP (except in top-ranking athletes) family members have WP at rest that promptly converts to regular sinus tachycardia with exercise. They also have mild apical noncompaction that has been quite stable.