Dysregulated arginine metabolism and cardiopulmonary dysfunction in patients with thalassaemia

Morris, C. R.; Kim, H. Y.; Klings, E. S.; Wood, J.; Porter, J. B.; Trachtenberg, F.; Sweeters, N.; Olivieri, N. F.; Kwiatkowski, J. L.; Virzi, L.; Hassell, K.; Taher, A.; Neufeld, E. J.; Thompson, A. A.; Larkin, S.; Suh, J. H.; Vichinsky, E. P.; Kuypers, F. A.

Br J Haematol. 2015 Apr 25; 169(6):887-98

Abstract

Pulmonary hypertension (PH) commonly develops in thalassaemia syndromes, but is poorly characterized. The goal of this study was to provide a comprehensive description of the cardiopulmonary and biological profile of patients with thalassaemia at risk for PH. A case-control study of thalassaemia patients at high versus low PH-risk was performed. A single cross-sectional measurement for variables reflecting cardiopulmonary status and biological pathophysiology were obtained, including Doppler-echocardiography, 6-min-walk-test, Borg Dyspnoea Score, New York Heart Association functional class, cardiac magnetic resonance imaging (MRI), chest-computerized tomography, pulmonary function testing and laboratory analyses targeting mechanisms of coagulation, inflammation, haemolysis, adhesion and the arginine-nitric oxide pathway. Twenty-seven thalassaemia patients were evaluated, 14 with an elevated tricuspid-regurgitant-jet-velocity (TRV) >/= 2.5 m/s. Patients with increased TRV had a higher frequency of splenectomy, and significantly larger right atrial size, left atrial volume and left septal-wall thickness on echocardiography and/or MRI, with elevated biomarkers of abnormal coagulation, lactate dehydrogenase (LDH) levels and arginase concentration, and lower arginine-bioavailability compared to low-risk patients. Arginase concentration correlated significantly to several echocardiography/MRI parameters of cardiovascular function in addition to global-arginine-bioavailability and biomarkers of haemolytic rate, including LDH, haemoglobin and bilirubin. Thalassaemia patients with a TRV >/= 2.5 m/s have additional echocardiography and cardiac-MRI parameters suggestive of right and left-sided cardiac dysfunction. In addition, low arginine bioavailability may contribute to cardiopulmonary dysfunction in beta-thalassaemia.

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