From the Guidelines
For an asymptomatic patient with Mobitz type 1 (Wenckebach) second-degree AV block on EKG, observation without specific intervention is typically recommended. These patients generally do not require immediate treatment as Mobitz type 1 is usually benign and occurs due to conduction delay at the AV node level rather than below it 1. The patient should undergo a thorough cardiac evaluation including a comprehensive history, physical examination, and possibly additional testing such as echocardiography to rule out structural heart disease.
Key Considerations
- It's essential to review and potentially discontinue medications that could exacerbate AV block, such as beta-blockers, calcium channel blockers, and digoxin.
- Regular follow-up with serial EKGs is advised to monitor for progression to higher-degree blocks.
- If the patient develops symptoms like syncope, pre-syncope, or exercise intolerance, or if the block progresses, referral to a cardiologist for consideration of pacemaker implantation would be appropriate, as indicated by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Rationale
The benign nature of asymptomatic Mobitz type 1 is due to its physiological mechanism, where there is progressive prolongation of the PR interval until a beat is dropped, after which the cycle repeats, indicating a functional rather than structural conduction issue in most cases. This understanding aligns with the guideline's emphasis on considering the presence of symptoms and the type of atrioventricular block when deciding on permanent pacing 1.
From the Research
Next Steps for Asymptomatic Patient with Mobitz Type 1 Second-Degree AV Block
- The patient's condition, Mobitz type 1 (Wenckebach) second-degree atrioventricular (AV) block, is generally considered benign, especially if the patient is asymptomatic 2.
- According to a study published in the American Heart Journal, asymptomatic athletes with Wenckebach second-degree AV block showed no deterioration of AV conduction over time and remained asymptomatic 2.
- The study suggests that Wenckebach second-degree AV block in asymptomatic individuals may be a vagally-induced benign feature, provided that AV conduction improves with reflex sympathetic maneuvers and normalizes with sympathomimetic and vagolytic drug administration and physical exercise 2.
- For asymptomatic patients with Mobitz type 1 second-degree AV block, the following steps may be considered:
- Monitoring of the patient's condition to ensure that it does not progress to a more severe form of AV block.
- Evaluation of the patient's response to reflex sympathetic maneuvers, such as exercise or drug administration (e.g., isoproterenol and atropine) 2.
- Consideration of invasive electrophysiological investigation if the patient's response to tests is abnormal or if there are concerns about the patient's prognosis 2.