Selection Bias Exists for Selection of Contemporary Atrial Fibrillation Ablation Patients

Abstract

Background: Atrial fibrillation (AF) is associated with increased thromboembolic stroke risk. The effect of rapid atrial rates on thrombogenesis in the human left atrium (LA) remains unknown.Methods: Twelve patients with AF undergoing catheter ablation in sinus rhythm (SR) and eight with supraventricular tachycardia (SVT) due to left-sided accessory pathways were studied with rapid atrial pacing at 150 bpm. Eight patients with AF in SR served as controls. Blood was sampled from the LA, right atrium (RA) and femoral vein (FV) at baseline and 15 min after pacing or in controls. Platelet activation (platelet P-selectin), thrombin generation [thrombin-antithrombin-complex (TAT)] endothelial dysfunction [asymmetric dimethylarginine (ADMA)] and platelet-derived inflammation [soluble-CD40-ligand (sCD40L)] were measured by flow cytometry and ELISA.Results: With rapid atrial pacing, thrombin generation increased significantly in the AF group (log TAT 1.29 ± 0.56 mcg/L at 15 min vs. 1.05 ± 0.34 at baseline; p < 0.01), specifically in the LA and RA compared to the FV. This was markedly observed in patients with AV dyssynchrony (p < 0.01). In contrast, thrombin generation decreased in the SVT group (p < 0.01) and control group (p < 0.01). Platelet activation increased in AF patients with pacing (log P-selectin 1.27 ± 0.10% vs. 1.14 ± 0.17%; p < 0.01), was unchanged in the SVT group (p = 0.8) and decreased in controls (p < 0.01). ADMA and sCD40L were unchanged in all three groups.Conclusion: Rapid atrial rates increase LA thrombin generation and platelet activation in patients with AF. This effect is accentuated with AV dyssynchrony. However, rapid atrial rates did not result in abnormal markers in SVT patients, suggesting the additional role of abnormal substrate in AF patients. http://dx. Aim: To assess the usefulness of seven-day event monitoring in evaluating symptoms suggestive of cardiac arrhythmias when ECG and 24 h Holter monitoring are non-diagnostic.Methods: All patients undergoing seven day event monitoring from January 2011 to February 2012 were included in the analysis. Indications included: palpitations (70%); atrial fibrillation/flutter (15%); pre-syncope (10%); syncope (2%). Prior ECG and 24 h Holter monitors were non-diagnostic.Results: Eighty-four patients were included (mean age 51 ± 17 years, 76% female). Referral sources were: cardiologists 86% (53% electrophysiologists); emergency physicians and general practitioners 14%. 360 events in total were recorded by 69 (82%) patients (maximum possible 15 per patient). Symptoms were: palpitations (55%); irregular heart beat (21%); pre-syncope (15%). Fiftyeight percent of patients had a defined symptom-related arrhythmia, including: atrial fibrillation/flutter (5%); supraventricular tachycardia > 10 s (6%); atrial runs < 10 beats (10%); ventricular ectopics (26%); atrial ectopics (35%); sinus pause > 3 s (1%); sinus tachycardia > 120 bpm at rest (10%). In the remaining 24% of symptomatic patients, sinus rhythm only was recorded.Conclusions: Seven-day event monitor...