Medication Use and Clinical Outcomes in ATTR Patients With and Without Atrial Fibrillation

Introduction
Atrial fibrillation (AF) is a prevalent arrhythmia in transthyretin amyloidosis (ATTR), with a prevalence ranging from 38% to 76% in wild-type ATTR (wtATTR). This study aimed to investigate the differences between ATTR patients with and without AF, focusing on medication differences and clinical characteristics over a follow-up period of 6 and 12 months.

Methods
In this retrospective, single-center study, patients with confirmed ATTR amyloidosis, diagnosed through scintigraphy or endomyocardial biopsy and receiving transthyretin stabiliser therapy, were included. Clinical and echocardiographic parameters, kidney function, and NT-proBNP levels were compared between the two groups. Changes in these parameters were also evaluated over 6 and 12 months of follow-up. Normally distributed data were reported as mean ± standard deviation, and non-normally distributed data as median (quartile 1-3). Statistical analysis involved two-sided t-tests or Mann-Whitney U tests for continuous variables and Chi-square tests for dichotomous variables, with p < 0.05 as significant. Ethics approval was granted by the University Duisburg-Essen (23-11500-BO).

 Results
Among the 194 screened patients (87% male, mean age 80), 132 (68%) patients had AF and 62 (32%) patients did not have AF. A significant portion of the AF group, 80 patients (61%), underwent rhythm control therapy, which included electrical cardioversion (34%), ablation (16%), and amiodarone (11%).

Significant differences in medication use were noted, AF patients showed higher beta-blocker (64% vs. 42%, p = 0.003) and diuretic use (84% vs. 58%, p < 0.0001) than non-AF patients. Interestingly, the rates of pacemaker or ICD implantation were similar between the two groups (18% vs. 15%; p = 0.5263). However, AF patients exhibited lower stroke volumes (50 ml [42–61] vs. 61 ml [50–74], p = 0.02), poorer renal function with elevated serum creatinine (p = 0.001), and significantly higher NT-proBNP levels (p < 0.0001). Functional capacity also remained poorer in the AF group, with 58% classified as New York Heart Association III or higher compared to 25% in non-AF patients at baseline (p < 0.0001).

Conclusion
Our findings suggest that AF significantly worsens the clinical outcomes in patients with ATTR-CM. Patients with AF exhibited poorer renal and cardiac profiles and demonstrated a greater need for targeted symptom management. Importantly, transthyretin stabilser therapy did not reduce the negative effects associated with AF, highlighting the necessity for specialised management strategies in this subgroup. Future studies should focus on evaluating alternative therapeutic approaches to enhance outcomes for ATTR-CM patients with AF.