Left ventricular-aortic coupling in sickle cell disease underlies diastolic dysfunction

Left ventricular (LV) diastolic dysfunction (DD) is associated with increased mortality in sickle cell disease (SCD) but its mechanisms are not well known, preventing the development of effective therapies. Our hypothesis was that DD in SCD may be due to changes in aortic properties. We studied 31 SCD patients (32±7yrs) and 12 normal controls (29±10yrs) who underwent echocardiography and MRI on the same day. LV diastolic function was assessed from echocardiography. MRI included velocity-encoded images of the aorta to measure ascending aortic cross-sectional area, stroke volume, distensibility, as well as volumes of the forward (FFV) and backward (BFV) blood flow. Compared to controls, SCD patients had increased aortic area, stroke volume, and both FFV and BFV, while distensibility was similar. DD was found in 5/31 patients (16%), in whom the increase in BFV and BFV/FFV ratio was even more pronounced, when compared to the remaining patients. Our findings suggest a potential mechanism of DD in SCD patients. Increased cardiac output induced by chronic anemia might be associated with aortic dilation, which may increase LV afterload (BFV), ultimately leading to LV DD. If confirmed in larger studies, these aortic changes could be targets for specific therapies as a way to prevent the development of DD in SCD.