Pulmonary hypertension is common among adults with sickle cell disease and carries a high risk of mortality, according to an analysis of community recruited patients with sickle cell haemoglobinopathy documented by high-pressure liquid chromatography.

Mark T. Gladwin, MD, National Institutes of Health, Bethesda, Maryland, United States, and colleagues assessed pulmonary-artery systolic pressure by Doppler echocardiography in 82 male and 113 female sickle cell disease patients in stable condition. The investigators defined pulmonary hypertension as a tricuspid regurgitant jet velocity of at least 2.5 m/second and assumed that pulmonary-artery pressures were normal in patients with trace or no tricuspid regurgitation. The researchers also evaluated 41 black control subjects, with age and sex distributions similar to the patients, for race-based comparisons of laboratory and echocardiographic data.

Doppler echocardiography identified pulmonary hypertension in 32% of the patients. Over a mean follow-up of 18 months, a tricuspid regurgitant jet velocity of at least 2.5 m/sec conferred a rate ratio of 10.1 for death, compared with a tricuspid regurgitant jet velocity less than 2.5 m/sec.

A logistic-regression analysis in 149 patients, that used the dichotomous variable of tricuspid regurgitant jet velocity of less than 2.5 m/sec or more than 2.5 m/sec, revealed that significant independent correlates of pulmonary hypertension were a self-reported history of cardiovascular or renal complications, increased systolic blood pressure, high levels of lactate dehydrogenase and of alkaline phosphatase, and low transferrin levels. These factors, the authors note, accounted for 35% of the variability in tricuspid regurgitant jet velocity.

Conversely, foetal haemoglobin level, white-cell count, platelet count, and hydroxyurea therapy were unrelated to pulmonary hypertension.

"Our findings suggest that the noninvasive measurement of tricuspid regurgitant jet velocity by echocardiography can be used to identify patients at high risk for death," the authors write, "and may thus be viewed as a prognostic tool analogous to transcranial carotid Doppler flow-velocity assessment, which is used to predict the risk of stroke in children with sickle cell disease." They conclude that "therapeutic trials of oxygen, warfarin, transfusion, and pulmonary vasodilator and remodeling medications are urgently required to evaluate their potential to decrease the substantial morbidity and mortality associated with pulmonary hypertension in this population."

Pulmonary hypertension as a risk factor for death in patients with sickle cell disease.
Engl J Med. 2004 Feb 26;350(9):886-95.
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