Introduction
As the most common sustained supraventricular arrhythmia, atrial fibrillation (AF) exists in more than 1% of the general population, becoming a crucial heath issue with life expectancy increasing, especially in North America and Europe.1 Most patients with symptomatic AF have impaired quality of life, together with psychological disorders, such as depression and anxiety.2 Furthermore, the older AF patients are at the higher risk of thromboembolism, heart failure, and dementia, contributing to increased mortality.3
Among multiple treatment strategies for AF, it is catheter ablation (CA) that predominantly isolates the pulmonary veins (PVs) via various energy sources and technologies, or in combination with patient-specific additional ablation.4 CA is a well-recognized treatment alternative for restoring and maintaining sinus rhythm due to interruption of arrhythmogenic pathways in the atrial substrate, elimination of the foci initiating AF, and modulation of cardiac autonomic innervation.5,6 Nevertheless, there are still more than 20% ablation-treated patients with paroxysmal AF suffering from arrhythmia recurrence, and the efficacy of CA on persistent AF is inferior to that on paroxysmal AF.7,8The underlying mechanisms of early recurrence within the first 3 months post-ablation are more likely to be related to temporary local inflammation, the formation of inhomogeneous scar tissue, and transient imbalances of autonomic activity.9,10 Regarding to late recurrence occurring after a 3-month blanking period, one of the most prominent reasons is reconnection of isolated PVs that is also associated with cardiac parasympathetic hypertonicity.11,12
Deceleration capacity (DC), an index assessing deceleration-related heart-rate variability (HRV), is usually regarded as an indicator of parasympathetic activity when calculated in accordance with phase-rectified signal averaging (PRSA) algorithm.13Owing to elimination of non-periodic components in a 24-hour Holter recording, DC is rarely affected by ectopic beats and artifacts, which is superior to the established HRV parameters. DC, initially designed for predicting cardiac mortality in post-infarction patients, was subsequently reported to have no connection with AF recurrence after circumferential or segmental PV isolation.14,15 Recent studies, however, have showed that DC was probably related to AF prognosis in ablation-treated patients.16,17Therefore, this systematic review and meta-analysis was performed for the purpose of investigating the relationship between DC and AF recurrence following ablation and evaluating the prognostic value of DC in ablation-treated patients.
Methods
This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; registration number CRD42023475061), which was subsequently administered as per the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and the Meta-analysis of Observational Studies in Epidemiology (MOOSE).18,19
Search strategy
A literature search was systematically carried out in the Embase, PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases from their inception until October 01, 2023. A synthesis of search keywords was mainly in relation to “deceleration capacity”, “vagal”, “parasympathetic”, “sympathetic”, “autonomic”, together with “atrial fibrillation” and “ablation”. There was no restriction on language. The bibliographies of relevant studies were manually searched to verify additional articles as well.
Eligibility criteria
The studies were included when fulfilling the following criteria: (1) retrospective or prospective observational studies; (2) ablation-treated participants with and without AF recurrence; (3) either the pre- and post-ablation data on DC in both recurrence and non-recurrence groups, or the ratios based on DC for predicting AF recurrence were available. There was no limitation on follow-up duration or sample size. The studies would be excluded if (1) they were case reports, reviews, dissertations, or duplicates; (2) they were only involving DC prior to ablation; (3) the data on DC was insufficient; (4) the full text couldn’t be retrieved.
After removing the duplicates, two reviewers (PKZT, LZH) independently screened the title and abstract of all the retrieved literature to exclude the irrelevant studies that didn’t contain the information on AF, DC and ablation. The remaining studies following the preliminary screening were assessed for eligibility based on full-text review. Ambiguities were addressed by consulting with a third author (CAY). The process of study selection was illustrated in Figure 1.