Patients with sickle cell disease (SCD) have a unique cardiomyopathy with restrictive physiology characterized by diastolic dysfunction, left atrial dilation, and normal systolic function, according to research published in JACC: Cardiovascular Imaging.
A total of 134 patients with SCD (median age: 11 years) were included in the 2-part study. All of the patients underwent screening echocardiography at steady-state (no acute SCD 3 weeks before or after) at Cincinnati Children’s Hospital Medical Center between 2007 and 2010. Researchers also conducted a meta-analysis of 68 cardiac studies involving SCD patients.
Cardiopulmonary complications are the leading cause of adult mortality among sickle cell disease patients. These complications include heart chamber dilation, diastolic dysfunction, elevated tricuspid regurgitant jet velocity (TRV), and pulmonary hypertension.
“Children and adults with SCD develop a unique cardiomyopathy that is best characterized as restrictive physiology superimposed on a hyperdynamic state,” the authors wrote. “Over time, the [left ventricle] enlarges and diasotolic dysfunction progresses. This unique cardiomyopathy, like other forms of [restrictive cardiomyopathy], can explain the secondary, passive mild elevations in TRV and [pulmonary arterial pressures] and is consistent with the high rate of cardiopulmonary mortality and sudden death in SCD.”
Researchers observed a significant enlargement of the left atrial volume (z-score: 3.1; P=.002), but the shortening fraction was normal (37.6% ± 4.7%). The lateral ratio of mitral velocity to early diastolic velocity of the mitral annulus was severely abnormal in 8% of patients, and the septal ratio was severely abnormal in 14% of patients. Both ratios indicate impaired diastolic function.
The lateral mitral annulus ratio and the TRV were associated with enlarged left atrial volume in SCD (P=.003 and P=.006, respectively).
The meta-analysis revealed significant left atrial diameter enlargement among the SCD patients when compared with the control group. There was also evidence of diastolic dysfunction and enlarged left ventricular end-diastolic dimension with normal shortening fraction. Most of the patients with pulmonary hypertension had pulmonary venous hypertension consistent with restrictive cardiac physiology.
“More studies are needed to identify the mechanisms that lead to restrictive physiology in SCD,” the authors noted. “Understanding the pathophysiology of SCD-related cardiomyopathy with restrictive physiology can lead to targeted therapies that prevent or delay cardiac pathology in SCD.”
Niss O, Quinn CT, Lane A, et al. The unique cardiomyopathy with restrictive physiology of sickle cell disease. JACC Cardiovasc Imag. 2016. doi:10.1016/j.jcmg.2015.05.013.