Mobitz II
Also calledMobitz type 2 · second-degree AV block type II · Mobitz 2 · second-degree AVB type II
Definition
A form of second-degree AV block in which, while the sinus (P-P) rate stays stable, single P waves intermittently fail to conduct without any change in the PR interval of the conducted beats (the PR is constant before and after the dropped beat). The block is usually infranodal, in the His-Purkinje system, is frequently accompanied by bundle branch block (a wide QRS), and carries a high risk of progression to complete heart block.
Clinical noteBecause the block is usually infranodal, it can progress rapidly and unexpectedly to complete heart block with a slow, unpredictable ventricular escape rhythm, even when symptoms are minimal.
Sources
- Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay. Circulation. 2019;140(8):e382-e482. doi.org/10.1161/CIR.0000000000000628
- Barold SS, Herweg B. Mobitz type II second-degree atrioventricular block: a commonly overdiagnosed and misinterpreted arrhythmia. Front Cardiovasc Med. 2024;11:1450705. doi.org/10.3389/fcvm.2024.1450705
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.