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  • GP ablation has been regarded as a vagal denervation procedu

    2019-06-25

    GP ablation has been regarded as a vagal denervation procedure that reduces the vagal tone in the atria and the vulnerability to AF. However, it is unclear how much vagal effect on the atrium is attenuated and how much of the atrium is denervated after the ablation. According to the GP mapping by Mcclelland et al. [39], a vagal reflex was present in the GPs near the atrioventricular groove even after the ablation. A histoanatomical study showed that more than 700 ganglions and 40,000 neurons are distributed in the whole atria and linked with each other. These data suggest that it is difficult to eliminate every GP activity to exclude all neural networks from the atrium. Lall et al. [41] examined the vagal denervation effects after a maze IV procedure with canine atria, and showed that the maze procedure partially denervated the atrium. However, Voeller et al. [37] demonstrated in patients that the box lesion isolating the entire posterior left atrium in the maze III procedure showed a significantly higher freedom from AF compared with a single connecting lesion between the inferior PVs, suggesting that connecting the lesion between the superior PVs denervated the GPs more extensively in the left atrial roof. More recently, Sakamoto et al. [42] examined the electrophysiologic attenuation and recovery of the atrial vagal effects after GP ablation alone or with standard surgical lesion sets for AF. They demonstrated that GP ablation significantly reduced atrial vagal innervation with restoration of vagal effects at 4 weeks, suggesting early atrial reinnervation (Fig. 8).
    Future perspective
    Conflict of interest
    Introduction Atrial fibrillation (AF) often exacerbates Rosiglitazone HCl weight failure (HF) and HF predisposes patients to the development and progression of AF [1,2]. This interplay between AF and HF significantly increases hospitalization and mortality. In patients with AF and HF, pharmacological rhythm control therapy was not found to be superior to rate control therapy [3], although it was reported that left ventricular (LV) function improved after catheter ablation for AF [4,5]. Catheter ablation for AF is therefore recommended for patients with HF [6]. However, some studies have shown that LV dysfunction is associated with poor clinical outcome of catheter ablation for AF [7–9]. In the last decade, ablation techniques and technologies have been developed for isolation of the pulmonary veins (PVs) [10,11]. In particular, the efficacy of PV isolation is limited for persistent AF. To improve clinical outcomes, ablation techniques for atrial substrate modification were also developed [12–14]. Stepwise ablation, which includes atrial substrate ablation in addition to PV isolation, is highly effective in treating persistent AF [15]. It is unknown whether LV dysfunction is a predictor of tachyarrhythmia recurrences, even with the stepwise ablation strategy. Furthermore, little is known about the association between tachyarrhythmia recurrence and changes in LV function after ablation for AF in HF patients.
    Methods
    Results Baseline characteristics of the 108 patients are shown in Table 1. Regardless of LVEF, patients with a history of HF had shorter AF and continuous AF durations and higher CHADS2 scores, and LA diameter than those in patients without a history of HF. All patients with history of HF and LVEF>45% showed improvement in NYHA functional class after rate control therapy; therefore, they were diagnosed as tachycardia-induced cardiomyopathy by the physicians who referred them.
    Discussion A stepwise ablation strategy was used in the present study. In this ablation strategy, electrogram-based ablation or linear ablation was performed in combination with PV isolation, and the desired procedural endpoint was termination of AF [15,16]. All atrial regions except the sinus node and atrioventricular node are candidates for ablation. Stepwise ablation is, therefore, considered to be optimal for patients with persistent AF, because AF substrates are ubiquitously distributed in the atria and PVs in these patients. In fact, the efficacy of stepwise ablation for patients without HF was 91% at the 1-year follow-up in this study, which is comparable to rates for paroxysmal AF. However, patients with reduced LVEF showed worse clinical outcome even after undergoing stepwise ablation strategy. This is consistent with previous reports in which different ablation strategies were used [8,9]. It remains possible that more extensive ablation with a high rate of AF termination may result in improved clinical outcomes for patients with LV dysfunction. Further studies are required to address this issue.