Detection of arrhythmias in patients with transthyretin cardiac amyloidosis

Abstract Introduction Arrhythmias are a very common manifestation of transthyretin cardiac amyloidosis (ATTR-CM). Atrial fibrillation and conduction disorders occur with high prevalence. Arrhythmias may be the first manifestation of the disease, leading to the diagnosis of ATTR-CM.The prevalence of non-sustained and sustained ventricular arrhythmias, as well as the occurrence of sudden cardiac death, remains less clear, as does the benefit of implantable cardioverter-defibrillators (ICDs). Objective To clarify the incidence and prevalence of arrhythmias in a group of patients with verified ATTR-CM who meet the criteria for treatment with tafamidis. We focus on the use of various detection methods and the potential benefits of intensive monitoring, particularly the use of an implantable loop recorder(ILR) and interrogations of cardiac implantable devices (CIDs). Methods In a group of 49 patients with ATTR-CM (47 with wild-type and 2 with hereditary form), the prevalence and incidence of arrhythmias were determined. Various detection methods have been used, including standard follow-up with electrocardiograms and intensive follow-up in patients with ILRs or CIDs (ICD or pacemaker). In patients with intensive monitoring, interrogations of CIDs (16 patients) or ILRs (5 patients) were performed on a regular basis. The median follow-up period was 19 months to date. Results The prevalence of atrial fibrillation/flutter in our cohort is currently 84% (41 patients), with 71% (29 patients) of these having detected arrhythmias before the diagnosis of ATTR-CM. All of these patients were on anticoagulant therapy at the time of the ATTR-CM diagnosis. In 29% (12 patients), arrhythmias developed later during our monitoring. Anticoagulation was subsequently initiated in all these patients. 22% (11 patients) suffer from bradycardia requiring pacemaker(PM) implantation, with 6 of them having the device implanted for symptomatic sick sinus syndrome and 5 for high-degree atrioventricular blocks. Seven patients were diagnosed with ATTR-CM after PM implantation, while in 3 patients, PM implantation was indicated during further monitoring after the diagnosis of ATTR-CM was established. In 1 patient, the decision to implant PM was made at the time of the ATTR-CM diagnosis. In 1 of 6 patients with an ICD (primary prevention or CRT indication), ventricular arrhythmia requiring appropriate ICD therapy has been recorded. In 1 patient, inappropriate ICD therapies were documented. Rhythm disturbances that required treatment interventions have been identified in 4 patients thanks to intensive follow-up. Conclusion The prevalence of arrhythmias requiring therapeutic interventions is high in our cohort. Intensive heart rhythm monitoring in patients with transthyretin cardiac amyloidosis appears meaningful when conducted alongside standard monitoring. It may be beneficial in terms of possible changes in treatment strategy based on the detection of clinically relevant arrhythmias.