A 68-year-old man with no known cardiovascular risk factors or relevant personal or family history was referred to the cardiology outpatient clinic by his primary care physician for an incidental finding of extrasystoles in the electrocardiogram (Figure). He did not show any cardiac symptoms. Structural heart disease was ruled out with transthoracic echocardiography. Treatment with β-blockers was initiated and a Holter study was requested. This showed monomorphic extrasystoles in 31% of beats.
Which mechanism can explain his electrocardiogram?
- 1.
Second-degree 2:1 atrioventricular (AV) block caused by disease intrinsic to the conduction system
- 2.
Sinus P waves blocked by incomplete penetration of the ventricular extrasystole in the bundle of His
- 3.
Atrial premature extrasystoles blocked by a refractory AV node
- 4.
Ventricular extrasystoles with retrograde conduction to the atrium
Submit your diagnosis to http://www.revespcardiol.org/es/electroreto/71/2. The diagnosis will follow in the next issue (March 2018). #RetoECG.