Treatment of Symptomatic or Infranodal Second-Degree Mobitz Type I (Wenckebach) AV Block Without a Reversible Cause
Second-degree type 1 (Mobitz type I / Wenckebach) atrioventricular block typically presents with progressive PR-interval prolongation before a non-conducted beat. In most patients this block is benign and nodal in origin — but a specific subset requires active intervention.
This protocol applies when the block is either symptomatic, or when electrophysiology study (EPS) has localised it to the intra- or infra-His (infranodal) level, and no reversible or transient underlying cause has been identified.
Clinical scenario: Symptomatic Mobitz type I AV block, or infranodal (intra-/infra-His) localisation confirmed at EPS — in the absence of a correctable, transient cause. Infranodal block in this setting carries a high risk of progression to complete heart block, syncope, and sudden death, even when currently asymptomatic.
Treatment approach (partial overview)
The recommended intervention involves permanent pacemaker implantation. Specific pacing modality considerations are guided by individual patient factors, including age, frailty, and the anticipated frequency of pacing.
The complete structured regimen — including pacing mode selection, patient-specific considerations, and the full evidence-based algorithm — is available via the link below.
References
DOI: 10.1093/eurheartj/ehab364
- Pacing should be considered in patients with second-degree type 1 AVB that causes symptoms or is found to be located at intra- or infra-His levels at EPS.
- Infranodal block (rare in this form of block) carries a high risk of progression to complete heart block, syncope, and sudden death, and warrants pacing even in the absence of symptoms.
- Pacing is not recommended in patients with AVB due to transient causes that can be corrected and prevented.
- In patients with AVB, DDD should be preferred over single-chamber ventricular pacing to avoid pacemaker syndrome and to improve quality of life.
- On a case by case basis, in frail elderly patients, and/or when AVB is paroxysmal and pacing anticipated to be infrequent, VVIR pacing may be considered as it carries a lower complication rate.