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Title: Contributing factors and clinical relevance of early arrhythmia recurrence and electrical reconnection of the pulmonary veins following pulmonary vein isolation for atrial fibrillation
Author: Das, Moloy
ISNI:       0000 0004 6422 7909
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2017
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Pulmonary vein isolation (PVI) is the cornerstone of ablation for paroxysmal atrial fibrillation (AF). However, success rates from AF ablation are not as high as would be hoped and this body of work focussed on improving outcomes from this procedure. Late PV reconnection following PVI is very common and is strongly associated with atrial tachyarrhythmia (AT) recurrence. The primary study of this work involved a randomised controlled trial comparing standard care with a strategy of early repeat electrophysiology study, irrespective of symptoms, to assess for and treat PV reconnection. Patients were followed-up for 12 months with daily ECG monitoring using a portable monitor. This study demonstrated a reduction in AT recurrence and burden and an improvement in quality-of-life in the repeat study group. At present, a 3-month blanking period following PVI is recommended, during which AT recurrences are not deemed indicative of procedure failure. In a secondary study, the relationship between episodes of AT recorded within this 3-month blanking period and PV reconnection was studied. Early recurrence beyond 4 weeks after PVI was associated with PV reconnection, whereas recurrence within the first 4 weeks was not. Force-Time Integral is a commonly-used ablation lesion quality marker but has limitations. Ablation Index is a novel marker incorporating power along with contact force and time in a weighted formula. In a further study, the relationship between Ablation Index and late PV reconnection was examined. Reconnected segments had significantly lower minimum Ablation Index values than non-reconnected segments, and higher values were required to avoid reconnection in anterior/roof segments compared to posterior/inferior segments. In the final part of the work, the relationship between sites of acute PV reconnection that underwent re-ablation and sites of late reconnection was studied, as the effectiveness of such re-ablation is unclear. No difference was found in the rates of late reconnection between areas with and without acute reconnection. Taken together, the findings from these studies provide insights into the potential success rates that can be achieved from durable PVI in patients with paroxysmal AF, and techniques that may help to achieve this. Furthermore, assessment for early recurrence may allow better identification of those patients at higher risk of later recurrence.
Supervisor: Gupta, Dhiraj ; MacLeod, Ken Sponsor: Biosense Webster Inc.
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral