Patients with beta-thalassemia major demonstrated lower peak oxygen update, exercise capacity, and anaerobic threshold compared with volunteers without thalassemia, which was associated with cardiac iron overload, according to the results of a study published in the Annals of Hematology.
Lower capacity for exercise and abnormal respiratory function are known to be characteristic of beta-thalassemia; however, the underlying etiology is unknown. The aim of this study was to evaluate potential causes of exercise limitation in this population.
In the study, 54 adult patients with beta-thalassemia major who were transfusion-dependent and 20 matched healthy volunteers underwent cardiopulmonary exercise testing (CPET), cardiac echocardiography, and pulmonary function tests. Patients with beta-thalassemia also completed a physical activity questionnaire.
The mean age of the beta-thalassemia cohort was 37.4 and the mean body mass index was 22.4 kg/m2. There was no history or signs of acute cardiac disease.
Exercise performance was lower among patients with beta-thalassemia compared with healthy subjects. Patients with beta-thalassemia demonstrated an 81.5% decrease in peak oxygen uptake compared with controls.
The majority of CPET variables were significantly lower among patients with beta-thalassemia compared with controls without thalassemia, including peak oxygen uptake (P <.001), anaerobic threshold (P <.001), and oxygen pulse (P <.001). Muscular deconditioning mixed with cardiac dysfunction was the most common reason for limit in exercise capacity.
Reduced peak oxygen update and oxygen pulse were significantly associated with cardiac T2*, a proxy for cardiac iron overload.
Cardiac structural differences were also observed, as patients with beta-thalassemia demonstrated greater mean left atrial diameter and end systolic and diastolic diameters of the left ventricle, as well as a lower left ventricular ejection fraction (all P <.001).
The authors concluded that, “the most important causes of exercise limitation in these patients were muscular deconditioning and reduced cardiac inotropism due to iron deposition.” The authors recommended regulator physical activity may improve effort tolerance and, ultimately, quality of life.
Piatti G, Giuditta M, Cassinerio E, Cappellini MD, et al. Cardiopulmonary testing in adult patients with β‑thalassemia major in comparison to healthy subjects. Ann Hematol. Published online September 13, 2022. doi: 10.1007/s00277-022-04974-w