Not Your Usual Pre-Excitation

A 67-year-old man with a medical history of moderate to severe mitral regurgitation secondary to flail posterior mitral valve leaflet, hypertension, type II non–insulin-dependent diabetes mellitus, and paroxysmal atrial fibrillation was found to have the following ECG (Figure 1) after elective mitral valve repair. What abnormalities are present? Do you recommend further testing or treatment? Figure 1. ECG obtained after elective mitral valve repair. Please turn the page to read the diagnosis. The ECG (Figure 2) demonstrates normal sinus rhythm with pre-excitation but unexpectedly with progressively lengthening PR interval consistent with Mobitz I (Wenckebach) block. The seventh QRS complex (arrow) is a junctional escape beat …