P wave analysis in cryoballoon ablation and radiofrequency ablation in paroxysmal atrial fibrillation

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia in clinical practice and can increase stroke risk five times. AF also impairs quality of life (QoL) dramatically. Pulmonary vein isolation (PVI) has recently emerged as a successful intervention to treat symptomatic paroxysmal atrial fibrillation (PAF), superior to antiarrhythmic drugs (AADs). PVI could be performed using point-bypoint radiofrequency ablation (RF) or one-shot cryoballoon ablation (cryo). This thesis included a single-centre retrospective analysis comparing clinical outcomes in RF and cryo at 12 months. Pulmonary vein (PV) reconnection patterns after failed ablation were also examined to improve both ablation techniques in particular anatomical sites. The outcome was also calculated from a patient perspective using QoL paper questionnaires. The P wave represents atrial depolarisation and alterations in its morphology could demonstrate changes in atrial electrophysiology. P wave parameters using digital 12 leads electrocardiogram (ECG) directly before and after ablation were utilised to compare differences between both ablation modalities and to predict outcomes. P wave parameters were also used to predict repeat ablation outcomes in patients who failed their first PVI. The utility of P wave mapped by body surface mapping (BSM) was explored in predicting 12 months success rates for external direct current cardioversion (DCCV) in persistent atrial fibrillation (persAF). RF and cryo demonstrated similar clinical outcomes at 12 months, similar P wave parameter changes, similar QoL improvement regardless of additional ablations, and similar PV reconnection patterns. However, there was a trend toward right lower pulmonary vein (RLPV) reconnection after failed cryo. Multiple P wave parameter changes were observed after first and second ablations. However, the change in P wave terminal force in V1 (PTFV1) after second ablation was the only potential predictor of successful outcomes at 12 months. Increased PWDc was also predictive of DCCV failure at 12 months in patients on amiodarone. This thesis provided insights into the utility of P waves in comparing ablation techniques and predicting PVI and DCCV outcomes.