Left Atrial Enlargement Correlates with Inflammation and Oxidative Stress in Patients at High Risk for Atrial Fibrillation
Atrial Fibrillation (AF) is an extremely common arrhythmia affecting more than 5% of the population over 65 years of age. It is an independent risk factor for death. AF progresses over time, increasing in prevalence with age and converts from paroxysmal AF to permanent AF. AF is considered to be responsible for approximately one-sixth of all ischemic strokes in people over age 60 years. Large left atrial diameter (LAD) is associated with a high risk of AF in multiple patient populations. A case-control study comparing healthy volunteers to patient with idiopathic (lone) atrial fibrillation demonstrated that even patients with a first episode of AF had larger LA dimensions than those without AF. Atrial size is an independent predictor of risk of arrhythmia recurrence after radiofrequency (RF) ablation of atrial flutter and atrial fibrillation. Surgical data also shows “moderate” LAD is the strongest predictor of success for the mini-maze procedure . Inversely, reduction in atrial size predicts the post-operative success of sinus conversion with the RF maze procedure when used in conjunction with valvular surgery.
These data suggest increased LA size is a marker for the presence of an enhanced substrate for development of atrial fibrillation, due to atrial remodeling and that reversing this enlargement may decrease risk of atrial fibrillation. Conversely, atrial fibrillation leads to increase in left atrial size and decreasing rates of atrial fibrillation lead to reversed remodeling of the atrium. Several recent studies have linked increased oxidative stress with atrial fibrillation. In a pig model of atrial fibrillation, superoxide anions are up-regulated by a factor of 3.0, and nitric oxide is down-regulation by a factor of 3.7. In a recent project, we compared serum markers of inflammation and oxidative stress in a cross-sectional, case-control designed study of 22 subjects with persistent or permanent AF and controls. Multivariate models produced strong and significant associations between oxidative markers and atrial fibrillation , with inter-quartile odds ratios as high as 13.6.
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Journal of Clinical and Experimental Cardiology