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Atrial fibrillation is the most commonly encountered sustained cardiac arrhythmia. The aim of this thesis is to examine a number of advanced therapies for atrial fibrillation and accurately assess the efficacy of these interventions and further define the natural history of atrial fibrillation. The thesis begins with a historical review of atrial fibrillation and development of current treatments. Device therapy is assessed using pacemakers that have algorithms that avoid unnecessary, and seemingly pro-arrhythmic, ventricular pacing and have additional anti-AF algorithms, The short and long term effects of these algorithms are assessed. Minimal ventricular pacing algorithms are effective in reducing ventricular pacing. There is no significant reduction in AFB with these algorithms in the short term (Chapter 3). However, in the longer term (~ 12 months of followup), these algorithms result in reduced AF burden and reduced disease progression from paroxysmal to persistentAF (Chapter 4). The efficacy of percutaneous catheter ablation is then assessed using the continuous monitoring capabilities of implanted devices (Chapter 5). Catheter ablation(s) significantly reduced AF burden. Nine of 25 patients demonstrated no recurrence of arrhythmia during follow -up. Quality-of-life indices also showed significant improvement after ablation. The efficacy of surgical AF ablation is examined using prolonged external Holter monitoring (Chapter 6). At 6 months, 75% of patients were in sinus rhythm according to a single ECG, However, only 62% of patients were free from AF on extended 7-day Holter monitoring; all AF episodes in these patients were asymptomatic. Surgical RFA for the treatment of AF, during concomitant cardiac surgery, is a successful procedure and significantly reduces AF burden. However, 13% of patients have asymptomatic AF episodes only identified with continuous monitoring. The final study utilises the continuous monitoring capabilities of implanted devices to define a natural history of atrial fibrillation (Chapter 7). 356 patients with a mean follow-up period of 7.2 ± 3.1 years were included. 179 of 356 patients (50.3 %) had at least one episode of persistent AF. Of the 356 patients, 314 (88.2 %) had paroxysmal AF and 42 (11.8 %) had persistent AF at the time of diagnosis. The predominant AF subtype, at latest follow-up, was paroxysmal for 192 patients (53.9 %), persistent for 77 (21.6 %) and long-standing persistent/permanent for 87 (24.4 %). Although many patients with AF will have persistent episodes, long-term continuous pacemaker follow-up demonstrates that the majority will have a paroxysmal, as opposed to persistent, form of the arrhythmia. The thesis concludes with a summary of the main findings of the research conducted and discusses future directions for further research in the field of atrial fibrillation management (Chapter 8). |
