Immuno-Electrophysiological Mechanisms of Functional Electrical Connections Between Recipient and Donor Heart in Patients With Orthotopic Heart Transplantation Presenting With Atrial Arrhythmias.

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Effects of Alpha Lipoic Acid on Multiple Cytokines and Biomarkers and Recurrence of Atrial Fibrillation Within 1 Year of Catheter Ablation.

Catheter ablation (CA) is a procedure commonly used to restore sinus rhythm in patients with atrial fibrillation (AF). However, AF recurrence after CA remains a relevant clinical issue. We tested the effects of an oral antioxidant treatment (alpha lipoic acid [ALA]) on AF recurrence post-CA. Patients with paroxysmal AF have been enrolled in a randomized, prospective, double-blind, controlled placebo trial. After CA, patients have been randomly assigned to receive ALA oral supplementation (ALA group) or placebo (control group) and evaluated at baseline and after a 12-month follow-up: 73 patients completed the 12-month follow-up (ALA: 33 and control: 40). No significant difference has been detected between the 2 groups at baseline. Strikingly, 1 year after CA, ALA therapy significantly reduced serum markers of inflammation. However, there was no significant difference in AF recurrence events at follow-up comparing ALA with placebo group. Multivariate analysis revealed that the only independent prognostic risk factor for AF recurrence after CA is age. In conclusion, ALA therapy reduces serum levels of common markers of inflammation in ablated patients. Nevertheless, ALA does not prevent AF recurrence after an ablative treatment.

Atrial tachycardia provoked in the presence of activating autoantibodies to ß2-adrenergic receptor in the rabbit.

BACKGROUND: A recent clinical study of patients with inappropriate sinus tachycardia reported that autoantibodies to ß-adrenergic receptors (ß2ARs) could act as agonists to induce atrial arrhythmias. OBJECTIVE: To test the hypothesis that activating autoantibodies to the ß2AR in the rabbit atrium are arrhythmogenic. METHODS: Five New Zealand white rabbits were immunized with a ß2AR second extracellular loop peptide to raise ß2AR antibody titers. A catheter-based electrophysiologic study was performed on anesthetized rabbits before and after immunization. Arrhythmia occurrence was determined in response to burst pacing before and after the infusion of acetylcholine in incremental concentrations of 10 µM, 100 µM, and 1 mM at 1 mL/min. RESULTS: In the preimmune studies when ß2AR antibody titers were undetectable, of a total of 20 events, only 3 episodes of nonsustained (<10 seconds) atrial arrhythmias were induced. In the postimmune studies when ß2AR antibody titers ranged from 1:160,000 to 1:1.28 million, burst pacing induced 10 episodes of nonsustained or sustained (≥10 seconds) arrhythmias in 20 events (P = .04 vs preimmune; χ(2) and Fisher exact test). Taking into account only the sustained arrhythmias, there were 6 episodes in 20 events in the postimmune studies compared with 0 episodes in 20 events in the preimmune studies (P = .02). Immunized rabbits demonstrated immunoglobulin G deposition in the atria, and their sera induced significant activation of ß2AR in transfected cells in vitro compared to the preimmune sera. CONCLUSIONS: Enhanced autoantibody activation of ß2AR in the rabbit atrium leads to atrial arrhythmias mainly in the form of sustained atrial tachycardia.

Inflammation abnormalities and inducibility of atrial fibrillation after epicardial ganglionated plexi ablation.

BACKGROUND: Epicardial ganglionated plexi (GP) ablation can prevent atrial fibrillation inducibility. However, the long-term effects of GP ablation on atrial fibrillation have not been elucidated. METHODS: Thirteen adult dogs of either sex, weighing 13-17kg, were randomly assigned to a sham-operated group (n=6) or a GP ablation group (n=7). After right thoracotomy, the atrial effective refractory period (AERP) was measured and atrial fibrillation was induced by right atrial rapid burst pacing. Atrial fibrillation and AERP were remeasured after anterior right and inferior right GP ablation in the GP ablation group. The animals were allowed to recover for 8 weeks, after which atrial fibrillation and AERP were measured again. Concentrations of C-reactive protein, tumour necrosis factor-alpha (TNF-α) and interleukin-6 were measured in the blood and atrial tissues. RESULTS: After 8 weeks, atrial fibrillation was induced in all animals in the GP ablation group. AERP and dispersion of AERP (dAERP; maximum AERP minus minimum AERP) were increased after GP ablation but AERP recovered after 8 weeks. There were no significant differences in the concentrations of C-reactive protein, TNF-α or interleukin-6 in venous blood between the two groups and the concentration of C-reactive protein in the atrium did not change before and after GP ablation. However, the concentrations of TNF-α and interleukin-6 in the atrium increased significantly 8 weeks after GP ablation (P<0.05). CONCLUSION: Increased concentrations of TNF-α and interleukin-6 in the atrium after GP ablation provide a new causative factor in terms of atrial fibrillation vulnerability.