Where Is the Level of Atrioventricular Block?

Abstract

ECG CHALLENGEA 66-year-old woman presented to the clinic with complaints of New York Heart Association Class II exertional dyspnea and easy fatiguability for 3 months.General physical and cardiac examination were normal.The baseline ECG and echocardiography were also unremarkable.A treadmill stress ECG test with the Bruce protocol revealed the development of 2:1 atrioventricular block in Stage III, with narrow QRS complexes (Figure 1).The patient further underwent electrophysiology study for evaluation of conduction system disease.The 12-lead ECG at baseline during the study is demonstrated in Figure 2. How do we reconcile these findings?What is the level of atrioventricular block?Please turn the page to read the diagnosis.