Prolonged QTc interval in children and young adults with sickle cell disease at steady state

Background. Prolongation of the QTc interval may be more common than previously believed among individuals with sickle cell disease (SCD). The clinical associations and natural history of QTc prolongation remain unclear in this population. Our objectives were to determine the prevalence of prolonged QTc and evaluate its relationship to clinical factors in children and young adults with SCD. Procedures. We analyzed data from subjects 10 to 25 years old with SCD enrolled in our pulmonary hypertension screening protocol. Screening included echocardiography (ECHO), 12-lead electrocardiogram (ECG) and laboratory testing at steady state. QTc interval >440 msec was considered prolonged. Results. ECG data from 76 subjects (57% male, mean age 14.2±3 years old, range 10-24) were analyzed. We observed prolonged QTc in 29/76 (38%) subjects. Despite evidence of left ventricular hypertrophy (LVH) in 50/76 (66%) subjects, the frequency of LVH was not significantly different in subjects with and without QTc prolongation. When compared to subjects with normal QTc, subjects with prolonged QTc had higher mean tricuspid regurgitant jet velocity (2.51±0.27 m/sec vs. 2.33±0.26 m/sec, P=0.010) as well as higher mean lactate dehydrogenase (433±142 IU/L vs. 343±142 IU/L, P=0.000) and aspartate aminotransferase (48±20 IU/L vs. 39±15 IU/L, P=0.026). A larger proportion of subjects with prolonged QTc also had a history of recurrent acute chest syndrome (66% vs. 38%, P=0.038). Conclusions. We conclude that QTc prolongation is a frequent finding in SCD not associated with LVH. Elevated pulmonary pressures, hemolysis and acute chest syndrome may represent risk factors for prolonged QTc in this population.