Atrial Fibrillation in β-Thalassemia: Overview of Mechanism, Significance and Clinical Management

Abstract

Thalassemia is an inherited blood disorder with worldwide distribution. Transfusion and chelation therapy have radically improved the prognosis of β-thalassemic patients in the developed world, but this has led to the development of new chronic cardiac complications like atrial fibrillation (AF). Prevalence of AF in patients with β-thalassemia is higher than in the general population, ranging from 2 to 33%. Studies are lacking, and the little evidence available comes from a small number of observational studies. The pathophysiology is not well understood but, while iron overload seems to be the principal mechanism, AF could develop even in the absence of iron deposition. Furthermore, the clinical presentation is mainly paroxysmal, and patients are highly symptomatic. The underlying disease, the pathophysiology, and the clinical presentation require a different management of AF in β-thalassemia than in the general population. Rhythm control should be preferred over rate control, and the most important antiarrhythmic therapy is represented by chelation drugs. Thromboembolic risk is high, but the available risk scores are not validated in β-thalassemia, and the choice of anticoagulation therapy should be considered early. The main purpose of this review is to summarize the actual knowledge about AF in β-thalassemia, with a specific focus on the clinical management of these complex patients.

Keywords: ablation; arrhythmias; atrial fibrillation; chelation; heart; hemoglobinopathy; iron; supraventricular; thalassemia.

Figure 1

Pathophysiology of atrial fibrillation in β-thalassemia.

Figure 2

Electroanatomical mapping of left atrium in a patient with β-thalassemia and atrial fibrillation. Panel on the left: right anterior oblique view. Panel on the right: posteroanterior view. Colors indicate electrical potentials. The red color indicates regions with low voltages (<0.05 mV) while purple color indicates normal voltages (>0.24 mV). Of note, a large part of the left atrium shows low electrical potentials, consistent with fibrosis, while normal voltages, identifying healthy muscular walls represent only a small, patchy part of the atrium. MV: mitral valve; LAA: left atrial appendage; LSPV: left superior pulmonary vein; RSPV: right superior pulmonary vein; RIPV: right inferior pulmonary vein.