Characterisation of atrial fibrillation patients: risk factors, progression, gender and thrombogenic risk

Abstract

Atrial fibrillation (AF) is the most common cardiac arrhythmia which is fast reaching epidemic measures. This thesis evaluates several aspects of AF: the role of AF screening, risk factor management in reversal of the AF substrate, impact of socio-economic background and risk-factor management, gender and ablation outcomes, thrombogenic risk following ablation and anticoagulation treatments. Screening to detect AF prevalence and asymptomatic AF is increasingly being evaluated to reduce complications. Chapter 2 evaluates the results of a nationwide screening event. This study provides insight into detection rates around Australia and New Zealand. Additionally, due to the information collected we were able to establish the risk of AF development in individuals based on their risk factor profile. Screening enabled raised awareness of the AF and an opportunity to educate individuals on their individual risk factors. AF is well demonstrated to be a progressive disease. Many patients present with short paroxysmal episodes which over time become long-lasting and eventually persistent in nature. Chapter 3 presents the REVERSE-AF study which demonstrated that with increasing weight-loss there is an increase likelihood of AF reversal. Patients who were able to achieve >10% weight-loss were more likely to have AF reversal with 88% of patients reversing from persistent to paroxysmal or no AF at follow-up. The role of socioeconomic determinants on risk factor management in AF is not well studied. Chapter 4 investigates the socioeconomic influence on patients undergoing risk factor management and AF outcomes. Despite evaluating many factors of socioeconomic background, no specific factor demonstrated an association with AF freedom. Interestingly, we did note that married individuals were able to achieve greater weight-loss. This has important implications suggesting that socio-economic boundaries are not determinants of the success of risk-factor management in AF. Socioeconomic status in not a barrier to successful risk-factor management in AF. Ablation has been shown to be successful in treating patients with AF. The difference between outcomes of genders is very varied in the current literature, with women often having worse outcomes. In chapter 5 we present the long-term follow-up data, assessing ablation outcomes. This study found women present with more paroxysmal AF and a smaller atrium. Despite this, women are more likely to have AF recurrence over long-term follow-up. This data adds further weight for biological differences between genders in the outcomes of AF management. Stroke is one of the most devastating outcomes of AF; however, it has a complex pathophysiological basis. As such chapter 6 evaluates a large cohort of patients undergoing AF ablation to shed light on the impact of eliminating AF. Interestingly despite eliminating arrhythmia, a small group of individuals had a stroke during follow-up. This demonstrates that AF itself remains only one component of the risk of stroke in patients with AF; highlighting ongoing vigilance is needed in managing all stroke risk factors. Additionally, further caution and evaluation is required to cease anticoagulation after successful catheter ablation of AF. Finally, Non-vitamin K antagonists (NOAC) have become a popular method of anticoagulation for AF patients in the prevention of stroke. It has been suggested there is a significant discontinuation rate warranting the evaluation of non-pharmacological strategies for stroke prevention. Chapter 7 evaluates cessation rates in a single-centre when prescription is undertaken in an integrated care setting. Interestingly, despite suggestions in the literature, we found with appropriate education and individual participation in decision making, the rate of cessation was low. Age and gender were independent predictors of NOAC cessation. This data highlights the need for improved care pathways and delivery to improve compliance with proven therapies.