From the Guidelines
Reversion pauses in atrial fibrillation (AF) occur due to the complex interplay of enhanced automaticity and reentry mechanisms in the heart, which can lead to transient electrical silence after cardioversion. The exact mechanism of these pauses is not fully understood, but it is thought to involve the temporary suppression of the sinoatrial node during AF, which needs time to recover its normal function after cardioversion 1.
Key Factors Contributing to Reversion Pauses
- Enhanced automaticity in one or several rapidly depolarizing foci
- Reentry involving one or more circuits
- Temporary suppression of the sinoatrial node during AF
- Underlying heart disease, which can affect the severity of AF and the risk of complications, including mortality, which is about double that of patients in normal sinus rhythm 1
Clinical Considerations
- The risk of significant pauses is one reason why cardioversion is typically performed in monitored settings where immediate intervention is possible if dangerous bradycardia occurs
- Patients with sick sinus syndrome or those taking medications that slow heart rate are at higher risk for prolonged pauses
- A permanent pacemaker may be considered in patients with recurrent symptomatic pauses following cardioversion, especially if the pauses exceed 5 seconds or cause symptoms like syncope or pre-syncope
Outcome-Based Recommendation
Based on the current understanding of AF mechanisms and the potential risks associated with reversion pauses, it is crucial to carefully evaluate patients before cardioversion and to have temporary pacing capabilities available during the procedure. This approach can help minimize the risk of complications and improve outcomes for patients with AF, ultimately reducing morbidity, mortality, and improving quality of life 1.
From the Research
Reversion Pauses in Atrial Fibrillation
Reversion pauses in atrial fibrillation (AF) occur when there is a temporary cessation of the arrhythmia, followed by its resumption. The exact mechanisms behind these pauses are complex and not fully understood.
- The autonomic nervous system (ANS) plays a significant role in the initiation and maintenance of AF, as well as the occurrence of reversion pauses 2, 3, 4.
- Studies have shown that the ANS can induce significant changes in atrial electrophysiology, leading to the development of atrial tachyarrhythmias, including AF 4.
- The inter-relationships between the parasympathetic and sympathetic nervous systems can contribute to alterations in conduction and refractoriness properties of the heart, which may lead to reversion pauses 3.
- Reversion pauses may also be related to the presence of triggered activity, which can be influenced by the ANS and other neurohumoral modulators 3.
- The clinical implications of reversion pauses in AF are not fully understood, but they may be an important factor in the management of the arrhythmia 5.
- Further research is needed to fully understand the mechanisms behind reversion pauses in AF and to develop effective therapeutic strategies for their management 6.