International Journal of Cardiovascular Sciences. 22/jul/2024;37:e20240050.

Heart Rate Control or Rhythm Control in Patients With Atrial Fibrillation and Cardiac Amyloidosis

Lígia Lopes Balsalobre Trevizan , Sandrigo Mangini

DOI: 10.36660/ijcs.20240050

Introduction

Cardiac amyloidosis (CA) manifests as a gradually progressive infiltrative condition characterized by the accumulation of insoluble protein aggregates within the myocardium and cardiac conduction system. The majority of CA cases are associated with precursor proteins, particularly immunoglobulin light chains (AL-CA) and transthyretin (ATTR-CA), which represent over 95% of cases. ATTR precursor substances may originate from a broad spectrum, encompassing both wild-type (ATTRwt) and variant (ATTRv) genes.

Arrhythmias in CA result from a combination of factors. The deposition of amyloid fibrils and infiltration into the myocardium cause thickening of the atrial and ventricular walls, leading to compromised relaxation. Consequently, this cascade results in increased filling pressures and atrial dilation, making individuals more susceptible to atrial fibrillation (AF) and other atrial arrhythmias. While left atrial (LA) enlargement has historically been linked with AF, new-onset AF can occur even without LA enlargement, suggesting a complex pathophysiology of AF in CA, where various processes affect LA structure, function, and mechanics in different ways, thereby heightening the AF risk. The usual manifestation of LA remodeling involves substantial infiltration of the atrial walls, leading to gradual impairment of atrial function and heightened stiffness, often observed without significant LA dilation.

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