Neurohormonal activation, Symptoms and health-related quality of life in patients with atrial fibrillation eligible for radiofrequency ablation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. In order to improve the management of patients with AF, a better understanding of patients’ arrhythmia-related symptoms and health-related quality of life (HRQoL), as well as a finer grasp of the effect of AF initiation and the revolutionary treatment of radiofrequency ablation (RFA) on neurohormonal balance are of great importance. The aim of this dissertation was to study the effects of RFA and AF initiation on four different neurohormonal systems represented by two cardiac biomarkers: the N-terminal fragment of the proB-type natriuretic peptide (NT-proBNP), the mid-regional fragment of the N-terminal of pro-atrial natriuretic peptide (MR-proANP); and two extra-cardiac biomarkers: the C-terminal fragment of the prodromal molecule of arginine vasopressin (copeptin) and the mid-regional portion of pro-adrenomedullin (MR-proADM). Furthermore, we aimed to correlate objective indicators with the variety of arrhythmiarelated symptoms and HRQoL in patients with AF. We studied 192 consecutive AF patients, eligible for RFA, referred to the University Hospital, Linköping, Sweden between January 2012 and April 2014. Forty-five patients, out of the initially selected sample, were included in the interventional part of the study. Biomarkers were collected from the femoral vein (fv), the coronary sinus (CS) and the left atrium (LA), and from fv immediately and the day after RFA. With regard to the interventional part of the study, 36 patients were randomized to AF initiation and 19 to control group. Biomarkers were retrieved from fv, CS and LA prior to AF initiation (baseline) and 30 minutes later. The Arrhythmia-Specific questionnaire in Tachycardia and Arrhythmia (ASTA) symptom scale was used in order to assess patients’ arrhythmiarelated symptoms. The ASTA HRQoL scale and the generic short-form 36 (SF-36) physical and mental component summaries were used in order to express patients’ disease-specific and overall HRQoL respectively. While analysing the effect of RFA on biomarkers, it was noticed that the level of NTproBNP decreased the day after RFA in participants in AF, compared with the participants in sinus rhythm who showed a slight increase. Regardless of the actual rhythm, the level of MR-proANP showed an increase immediately after RFA was carried out, followed by a decrease the day after. The copeptin level showed a six-fold increase, compared with baseline, immediately after the RFA procedure, while the MR-proADM level increased the day after. The levels of copeptin and MR-proADM were similar in the CS compared to peripheral blood. When it came to the effects of AF initiation on biomarkers, compared with the control group, MR-proANP and NT-proBNP concentrations were increased. Copeptin levels in patients without ischemic heart disease were decreased after the initiation of AF. We also found that signs of anxiety, low-grade inflammation (defined by high-sensitive C-reactive protein levels>3mg/l) and LA dilatation significantly predicted arrhythmiarelated symptoms. Probable depression was the most important predictor of arrhythmiaspecific HRQoL, and obesity and signs of anxiety were the most important predictors of the physical and mental component summaries respectively. AF is a complex arrhythmia that affects the cardiac and extra-cardiac neurohormonal balance directly after its initiation. RFA causes a neurohormonal imbalance not only due to secondary myocardial injury, but also due to other factors such as patient’s actual rhythm, volume overload and procedural stress. Treatable factors such as anxiety, depression and obesity, which can affect HRQoL and symptoms in patients with AF, should be addressed, and possibly a more intensive life style factor modification can be of value