Fibrillazione atriale e amiloidosi cardiaca AL: un connubio intrigante

Atrial fibrillation and cardiac amylodosis: an intriguing combination Primary systemic (AL) amyloidosis is a clonal plasma cell disorder in which the N-terminal fragments of monoclonal light chains form fibrils that accumulate in various organs, ultimately leading to organ dysfunction and death, that is very frequently caused associated with cardiac involvement. Since cardiac amyloidosis is characterized by severe left ventricular diastolic dysfunction, an impact on atrial structure and function is expected. This may lead to atrial dilatation and dysfunction, as well as to supraventricular arrhythmias, eventually causing atrial fibrillation (AF), with all the well-known sequelae on cardiac pump function and on the risk of thromboembolism. In literature the estimated prevalence of atrial fibrillation ranges from 10% to 15%, that is somewhat lower than expected, when considering the extent of diastolic dysfunction (and of the consequent left atrial enlargement). Since little is known this aspect of cardiac AL amyloidosis, aim of the present study was to analyze the prevalence of atrial fibrillation in this clinical setting, in comparison with similar cardiac phenotypes of diastolic heart failure, namely hypertensive heart disease, heart failure and hypertrophic cardiomiopathy. Left atrial anteroposterior diameter was used as estimate of atrial size. We enrolled 161 consecutive never-treated subjects, in whom a first diagnosis of primary AL amyloidosis was concluded between 2008 and 2009. None of the AL patients without cardiac involvement showed AF. Despite higher left atrial diameters and volumes, only 14 patients presented with atrial fibrillation, with a prevalence (8.7%) that was lower than in other forms of diastolic heart failure (ranging from 13 to 19%) with the exception of hypertensive heart disease (3%). Moreover, left atrial enlargement was more evident in cardiac AL than in the other populations, and the presence of AF in cardiac AL patients was significantly associated with left atrial diameter, area and volume (p<0.05 for all comparisons). Therefore, in cardiac amyloidosis, AF prevalence is lower than expected when considering the extent of diastolic dysfunction (and of the consequent left atrial enlargement) and the comparison with other patients with diastolic heart failure. Amyloid deposit may be playing a major role in determining such a low prevalence. Further studies are needed to investigate these aspects.