Factors Associated With Sickle Cell Disease and the Heart
What are the hematological and echocardiographic factors associated with cardiac involvement of sickle cell disease?
This was a longitudinal observational study that looked at 1,780 patients with sickle cell disease at a single center between 1999 and 2011. Patients were included with SS and S-β thalassemia. Six hundred and fifty-six patients were included with hematology and echocardiography data who had no prior cardiac surgery and no current pregnancy.
Six hundred and thirty-four patients had SS and 22 had S-β. Median age was 31 years and 43% were male. Left ventricular (LV) systolic dysfunction (LV ejection fraction [LVEF] <55%) was found in only 8.5% of patients and only three patients had LVEF <35%. Those patients in the fourth quartiles (Q4) of LV end-diastolic dimension and left atrial (LA) dimension index had a higher cardiac index compared to others despite lower LVEF and similar heart rates. Patients in Q4 also had lower hemoglobin concentration and red blood cell (RBC) counts, suggesting greater anemia severity as well as higher lactate dehydrogenase, bilirubin, and reticulocyte counts, suggesting greater hemolysis. Median follow-up was 48 months; 7.6% died and 5.8% were lost to follow-up. Factors significantly associated with mortality by univariate analysis (p < 0.20) in this patient subset were older age, lower LVEF, higher %dense RBC, and higher tricuspid regurgitation velocity (TRV). TRV >2.5 m/s was a predictor of mortality (area under the receiver operating characteristic curve, 0.70; 95% confidence interval, 0.57-0.83; p = 0.0001). Mortality increased when LVEF was <55%.
Cardiac dilation and higher cardiac indexes were associated with greater anemia and hemolysis in the patient population. TRV ≥2.5 m/s and LV dysfunction were a predictor of mortality.
It appears based on this study that LV, LA dilatation, cardac index elevation, and increased TRV were common in sickle cell disease. The risk of death was highest among those with both TRV ≥2.5 m/s and LVEF <55%.
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