Effects of carvedilol on cardiac autonomic nerve activities during sinus rhythm and atrial fibrillation in ambulatory dogs

Comparison of continuous 24-h and 14-day monitoring for detection of otherwise unknown atrial fibrillation: a registry to identify Japanese concealed atrial fibrillation (REAL-AF)-based study

Early detection of atrial fibrillation (AF) is desirable for preventing strokes. Not only does AF often go undetected in patients being followed up for various disease conditions, but the optimal detection method also remains to be elucidated. In a prospective observational study of 24-h Holter monitoring versus 14-day external loop recording performed for detection of previously undiagnosed AF in 868 Japanese outpatients (aged 75 ± 6 years), with a CHA2DS2-vasc score ≥ 1, but no prior AF episodes, AF was detected during the initial monitoring period in 16 (1.8%) patients, in 7 (1.1% [7/645]) by 24-h monitoring and 9 (4.0% [9/223]) by 14-day monitoring (P = 0.005), and overall in 32 (3.7%) during the 1-year study period. Absence of a beta-blocker therapy and the serum N-terminal pro-brain natriuretic peptide level were independent predictors of a new detection of AF. Oral anticoagulation (OAC) therapy was given to 22 (69%) of the 32 patients in whom AF was detected, and no difference in the incidence of subsequent major adverse events was found between the patients managed with and without oral OAC therapy. Previously unknown AF was documented at a prevalence of 3.7% per year among Japanese with a notable CHA₂DS₂-VASc score, and 14-day external loop monitoring was significantly more effective for detection of the disorder. A large-scale prospective AF screening study conducted to clarify the type or types of patients who would benefit from "early" OAC therapy for primary stroke prevention is warranted.

Ganglionated plexi as neuromodulation targets for atrial fibrillation

The autonomic nervous system plays an important role in the genesis of atrial fibrillation and is one of the candidate targets for atrial fibrillation therapy. This review focuses on the role of the autonomic nervous system in atrial fibrillation development and discusses the results of the ganglionated plexi catheter and surgical ablation in preclinical and clinical studies. The heart is innervated by the extrinsic and intrinsic autonomic nervous systems. The intrinsic autonomic nervous system consists of multiple ganglionated plexi and axons, which innervate the neighboring atrial myocardium and control their electrophysiological properties. Abnormal autonomic innervation has been observed in an animal model of atrial fibrillation and in humans. Direct recordings of autonomic nerve activity in canine models showed that atrial tachyarrhythmia episodes were invariably preceded by intrinsic cardiac autonomic nerve activity, thus supporting the importance of intrinsic cardiac autonomic nerve activity as the triggers for atrial tachyarrhythmia. Targeting ganglionated plexi with catheter ablation improves the outcomes of paroxysmal atrial fibrillation ablation in addition to pulmonary vein antrum isolation. Ablation of ganglionated plexi alone without pulmonary vein isolation is also useful in controlling paroxysmal atrial fibrillation in some patients. However, surgical ganglionated plexi ablation in patients with a large left atrium, persistent atrial fibrillation, and/or a history of prior catheter ablation does not result in additional benefits. These different outcomes suggest that ganglionated plexi ablation is effective in managing patients with paroxysmal atrial fibrillation, but its effects in patients with persistent atrial fibrillation and advanced atrial diseases might be limited.