The aim of this prospective, monocentric, non-randomized trial is to investigate the impact of catheter ablation of atrial tachyarrhythmias on the ABC-stroke and ABC-bleeding risk scores.

Participants planned for first catheter ablation for symptomatic atrial tachyarrrhythmias (atrial fibrillation, atrial flutter) will be enrolled. Serial blood samples will be collected before and 3, 6 and 12 months after catheter ablation to calculate the ABC scores as well as the traditional bleeding and stroke risks. Following catheter ablation, continuous rhythm monitoring will be achieved using an insertable monitor or an implanted atrial lead of a cardiac implantable electronic device. Additionally, heart rate monitoring via photoplethysmography using a smartwatch and/or smartphone is performed for a period of six months.

Data are analyzed for differences in ABC scores before and after ablation in relation to possible AF/AT recurrences. Furthermore, we are going to compare the sensitivity and specificity of different follow-up modalities post ablation. The monitoring via ICM (gold standard) is compared to smartwatch-based monitoring alone, versus smartphone-based monitoring alone or a combination of both for AT/AF recurrences.

Atrial arrhythmias (e.g. atrial fibrillation, atrial flutter) are common arrhythmias in the general population and are associated with an increased risk for heart failure, stroke and systemic embolism. Guidelines recommend the start of oral anticoagulation for patients with atrial fibrillation and an increased risk for stroke, calculated using a common risk score, the CHA2DS2-VASc score, which is solely based on clinical variables (congestive heart failure, hypertension, diabetes mellitus, vascular disease, sex category, age and history of stroke). Clinical bleeding risk scores (e.g. HAS-BLED score) can be used to identify the bleeding risk for patients considered for the use of oral anticoagulation. Nevertheless, clinical based risk scores provide only moderate discrimination of risk for the individual patient. Recent studies have shown that biomarkers, such as NT-proBNP, hs-Troponin T, hemoglobin and GDF-15, are related to the risk of stroke and other outcomes of patients with atrial fibrillation. Combining the use of clinical parameters and the most important biomarkers named above, the ABC (age, biomarkers, clinical history)-stroke risk score and the ABC bleeding risk score were developed and internally as well as externally validated. Both, the ABC stroke risk score and the ABC bleeding risk score performed better than commonly used scores (CHA2DS2-VASc, HAS-BLED, ORBIT) and are suggested as useful tools for improved risk stratification and clinical decision making in patients with atrial fibrillation. For symptomatic atrial arrhythmias, catheter ablation is an accepted and recommended strategy for rhythm control. Registry data suggest a decrease in stroke rates following catheter ablation for atrial fibrillation. Prospective randomized trials are currently evaluating if oral anticoagulation can be stopped after successful catheter ablation. The impact of catheter ablation on the ABC scores as well as the usefulness of the ABC scores for clinical decision making after catheter ablation are unknown. We hypothesize that successful catheter ablation of atrial arrhythmia has an impact on biomarkers of the ABC scores and may alter ABC-predicted stroke and bleeding risk.

Serial blood samples during routine blood tests will be collected to calculate the ABC-stroke and bleeding scores after informed consent before and 3, 6 and 12 months after catheter ablation. Taken blood samples are going to be centrifugated and stored for possible further analysis. Clinical data will be collected to allow calculation of the CHADS2, CHA2DS2-VASc, HAS-BLED, ORBIT, HEMORR2HAGES and ATRIA scores. Additionally, patient characteristics, the clinical history, type of atrial tachycardia, concomitant medication, prescribed anticoagulation as well as the clinical history for atrial tachyarrhythmia recurrence, stroke, systemic embolism, bleeding 3, 6 and 12 months after catheter ablation are acquired. Patients undergo transthoracic echocardiogram on Day 0 as well as after 3, 6 and 12 months after catheter ablation analyzing echoparameters important for structural cardiac changes regarding atrial fibrillation following catheter ablation.

Following catheter ablation, an insertable cardiac monitor is going to be implanted (not necessary for patients with an implanted pacemaker with a functional atrial electrode) for monitoring of recurrences of atrial tachycardias during follow-up. Furthermore, additional heart rhythm monitoring via photoplethysmography (PPG) via the application "FibriCheck" (Fibricheck, Corda Campus, Kempische Steenweg 303/27, 3500 Hasselt, Belgium, www.fibricheck.com) is performed for a period of six months. Patients receive both a FibriCheck smartphone application and a Fitbit smartwatch with the semi-continuous monitoring solution. The smartwatch performs photoplethysmography-based recordings for one minute every nine minutes automatically. Patients are trained to manually record a photoplethysmography-based episode via the smartphone twice a day and in case of symptoms.

Furthermore, patient-reported outcomes are going to be evaluated at inclusion as well as at every follow-up asking the patients to fill in three validated questionnaires on quality of life: EQ-5D-5L, AFEQT and HADS.

Data are analyzed for differences in ABC scores before and after ablation in relation to possible AF-/AT recurrences. Furthermore, we are going to compare the sensitivity and specificity of different follow-up modalities post ablation. The monitoring via ICM (gold standard) is compared to smartwatch-based monitoring alone, versus smartphone-based monitoring alone or a combination of both for AT/AF recurrences.

Inclusion Criteria:

• Symptomatic atrial tachyarrhythmias (atrial fibrillation, atrial flutter)
• Planned for 1st right or left atrial ablation
• Informed consent
• at least 18 years

Exclusion Criteria:

• Previous left or right atrial ablation
• Ineligibility for catheter ablation
• History of TIA / stroke
• < 18 years
• LA thrombus formation or history of thrombus formation

Patients planned to undergo first catheter ablation for symptomatic atrial tachyarrhythmias (atrial fibrillation, atrial flutter) will be enrolled.