Sinus Node Dysfunction and Atrial Fibrillation: A Reversible Phenomenon?
BACKGROUND
Symptomatic sinus node dysfunction (SND) consists of a variety of manifestations, including tachycardia-bradycardia syndrome. Atrial fibrillation (AF) is commonly associated with SND, which complicates the management of both conditions. This paper reviews the epidemiology, pathophysiology, and clinical trial data investigating therapeutic approaches for treatment of patients with both SND and AF.


METHODS
The authors reviewed articles published in English describing the epidemiology, pathophysiology, and therapeutic approaches for patients with SND and AF. The search was conducted using PubMed. Keywords included: sick sinus syndrome, sinus node dysfunction, atrial fibrillation, pacing, and pulmonary vein isolation.


RESULTS
SND affects up to one in five patients with AF. AF can lead to anatomical and electrophysiological remodeling in both atria, including the region of sinoatrial node. Changes including atrial fibrosis, altered calcium channel metabolism, and transformed gene expression have been demonstrated in patients with AF and SND. Nonrandomized clinical trial data have failed to demonstrate whether any pacing strategy can reduce the risk of AF. Pulmonary vein isolation appears to decrease episodes of tachybrady syndrome and sinus pauses.


CONCLUSIONS
SND affects up to one in five patients with AF. The pathophysiological derangements in gene expression, ion channel metabolism, and alterations in myocardial architecture associated with AF may lead to anatomic and electrical changes in the region of the sinoatrial node. Ablation may improve symptoms associated with SND in patients with AF. Future randomized trials are needed to clarify the epidemiology and optimal management of patients with SND and AF.
Duke Clinical Research Institute.|Duke University School of Medicine, Durham, North Carolina.
Larry R
LR
Jackson
Columbia University College of Physicians and Surgeons, New York City, New York.
Bharath
B
Rathakrishnan
Department of Pharmacy, Duke University Medical Center, Durham, North Carolina.
Kristen
K
Campbell
Duke Clinical Research Institute.|Duke University School of Medicine, Durham, North Carolina.
Kevin L
KL
Thomas
Duke Clinical Research Institute.|Duke University School of Medicine, Durham, North Carolina.
Jonathan P
JP
Piccini
Division of Adult Cardiac Electrophysiology, Duke University Medical Center, Durham, North Carolina.
Tristram
T
Bahnson
Duke University School of Medicine, Durham, North Carolina.
Jonathan A
JA
Stiber
Duke Clinical Research Institute.|Columbia University College of Physicians and Surgeons, New York City, New York.
James P
JP
Daubert
D058606:Accessory Atrioventricular Bundle / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D000328:Adult; D001281:Atrial Fibrillation / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D003937:Diagnosis, Differential; D004569:Electroencephalography / Q000379:methods; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D012849:Sinoatrial Node / Q000503:physiopathology; D013615:Tachycardia, Sinoatrial Nodal Reentry / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*
atrial fibrillation; electrophysiology - clinical; pacing