Key result
Atrial fibrillation and sick sinus syndrome frequently coexist, with evidence suggesting that atrial fibrillation can induce sinus node dysfunction through electrical remodeling, and vice versa.
This review highlights the bidirectional relationship between atrial fibrillation and sick sinus syndrome, emphasizing that AF can cause sinus node dysfunction and vice versa.
Alerts clinicians to screen for coexisting sinus node dysfunction in AF; confirms bidirectional remodeling but leaves open causal trials.
Atrial fibrillation (AF) and sick sinus syndrome (SSS) are two conditions that frequently coexist. Despite a wealth of available knowledge, the link between these two entities is poorly understood. Whether AF is a harbinger of SSS or whether SSS predisposes to AF has been the subject of much debate. AF results in sinus node remodeling on a cellular and molecular basis that may promote SSS. However, not all patients with atrial fibrillation have SSS. Though “AF begets AF”, AF may also beget SSS; and SSS may also beget AF. Multiple studies have demonstrated that sinus node dysfunction may precede the onset of AF. This review will focus on alterations to sinus node structure and function, overdrive suppression, ion channel remodeling, and transient myocardial ischemia as possible mechanisms associated with AF induced SSS. In addition, we will review evidence suggesting that SSS, characterized by a combination of atrial extrasystoles, dispersion of excitability recovery and sinus node ischemia, may lead to AF. Additional factors common to both conditions such as aging and interstitial atrial fibrosis, may explain their coexistence. All this raises many therapeutic challenges associated with the interplay of AF and SSS.
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Kezerashvili et al. (2008) conducted a review in Atrial Fibrillation and Sick Sinus Syndrome. Atrial fibrillation and sick sinus syndrome frequently coexist, with evidence suggesting that atrial fibrillation can induce sinus node dysfunction through electrical remodeling, and vice versa.
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