Electrophysiological Manifestations of Cardiac Amyloidosis

Abstract

Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy caused by the extracellular deposition of amyloid fibrils in the myocardium. Although cardiac amyloidosis patients primarily present with heart failure symptoms, arrhythmias and conduction system disease are frequently encountered. Atrial fibrillation (AF) is observed in up to 70% of patients at the time of diagnosis, and patients typically have controlled ventricular rates caused by concomitant conduction system disease. Thromboembolic risk is particularly high in patients with CA and AF, and left atrial thrombi have been observed even in the absence of clinically diagnosed AF. Atrioventricular nodal and infra-Hisian disease are common, and permanent pacemakers are frequently required. The use of implantable cardioverter-defibrillators in this population is controversial. This review summarizes the published data and therapeutic strategies surrounding arrhythmias and conduction system disease with the goal of aiding clinicians managing the clinical complexities of CA.

Incidence and risk factors for pacemaker implantation in light‐chain and transthyretin cardiac amyloidosis

“…To the best of our knowledge, only a single study investigated the prevalence and incidence of high‐grade AV block requiring PM implantation in a cohort of ATTR‐CA 7 . Of note, in line with our results, the authors reported similar findings with 9.5% of patients receiving PM implantation before the diagnosis and 11% of patients developing clinical indications to device implantation during follow‐up 5,7 . Therefore, our findings confirm previous observations and further extend the validity of the results also for patients with AL‐CA.…”

“…This condition results most frequently from age‐related failure of homoeostatic mechanisms in wild‐type transthyretin (ATTRwt) amyloidosis, destabilizing mutations in variant ATTR (ATTRv) amyloidosis or an haematological disorder in immunoglobulin light‐chain (AL) amyloidosis 2 . Although patients often seek medical attention for the development of signs and symptoms of HF, 3,4 arrhythmias and conduction system diseases are common in CA, namely atrial fibrillation (AF), sinus node dysfunction and atrioventricular (AV) blocks 5,6 . Data regarding the incidence and prevalence of pacemaker (PM) implantation in CA are extremely scarce and focused only on ATTR‐CA 7 .…”

“…2 Although patients often seek medical attention for the development of signs and symptoms of HF, 3,4 arrhythmias and conduction system diseases are common in CA, namely atrial fibrillation (AF), sinus node dysfunction and atrioventricular (AV) blocks. 5,6 Data regarding the incidence and prevalence of pacemaker (PM) implantation in CA are extremely scarce and focused only on ATTR-CA. 7 To the best of our knowledge, a single study on ATTR-CA reported that 10% of patients already had a PM in situ at the time of CA diagnosis and 11% underwent PM implantation during follow-up.…”

Predicting pacemaker implantation in cardiac amyloidosis: let's start with an ECG

“…The most accepted pathophysiologic mechanism for cardiac conduction system disease in CA is the infiltration of the conduction system by misfolded proteins, 5 as well as fibrosis of the sinoatrial node and atrioventricular conduction network 4 . Another potential mechanism could be direct toxic effect of amyloid fibrils, especially in light‐chain (AL)‐CA 6 …”

“…4 Another potential mechanism could be direct toxic effect of amyloid fibrils, especially in light-chain (AL)-CA. 6 Current European Society of Cardiology pacing and cardiac resynchronization therapy guidelines do not include a specific therapeutic approach in patients with CA. 7 However, they consider CA as one of the underlying structural heart diseases in which bradycardia and cardiac conduction disturbances are more frequent.…”