CARDIOVASCULAR FUNCTION DURING REST AND EXERCISE IN PATIENTS WITH SICKLE-CELL-ANEMIA AND COEXISTING ALPHA-THALASSEMIA-2

Cardiac function was measured at rest and during exercise in 9 patient s with sickle-cell anemia (SS) and coexisting homozygous alpha thalass emia-2 (alpha thal-2). Results were compared with 18 sickle cell patie nts with normal alpha globin genes, who were matched to the study grou p by age, gender, and size, and to published normal values. SS alpha t hal-2 patients were less anemic: 9.9 +/- 1.0 vs 8.2 +/- 1.2 gm/dl for SS alone (P < .05). Left ventricular dimensions were normal in SS alph a thal-2 (4.9 +/- 0.7 cm), but increased in SS (5.4 +/- 0.7, cm P = .0 5) (normal range, 3.7-5.6 cm). Left ventricular wall thickness was, ho wever, dramatically increased in the SS alpha thal-2 patients (free wa ll, 1.8 +/- 0.6 cm; septum, 1.6 +/- 0.4 cm), though SS controls had no rmal wall thickness (free wall, 1.0 +/- 0.2 cm; septum, 1.0 +/- 0.2 cm , P < .001)(normal range, 0.6-1.1 cm). At rest, Doppler indices of sys tolic function were not significantly different between sickle groups and normal values, SS alpha thal-2 patients did have abnormal diastoli c filling at rest, as evidenced by a reduced ratio of early/late diast olic filling, 1.4 +/- 0.3 vs. 2.0 +/- 0.5 for SS controls (P < .01), a nd 1.8 +/- 0.4 for normals. An analysis of covariance suggested that t his abnormality persisted after taking into account the previously dem onstrated hypertrophy. During exercise, SS alpha thal-2 patients had h igher heart rates and blood pressures than SS controls in spite of per forming the same or less work. This resulted in a higher double produc t (an estimate of oxygen consumption) in SS alpha thal-2 patients (37, 470 +/- 2,310 mm Hg-BPM) than in SS controls (33,310 +/- 1,490 mm Hg-B PM, P < .01). Work capacity, peak heart rate, and blood pressure were all abnormally decreased in both sickle-cell groups when compared to n ormal. Cardiac abnormalities noted at rest and during exercise in SS a lpha thal-2 patients suggest a role of microvascular occlusion and a p rotective effect of decreased hemoglobin. (C) 1996 Wiley-Liss, Inc.