Restrictive cardiomyopathy is associated with nephropathy in sickle cell anemia

Background: Cardiopulmonary and renal complications are major causes of morbidity and mortality in sickle cell anemia (SCA). Recently, we have observed that SCA is characterized by a unique cardiomyopathy, with features of both restrictive physiology (diastolic dysfunction, disproportionate left atrial (LA) enlargement and normal systolic function) and an anemia-related hyperdynamic state with ventricular enlargement. Restrictive physiology could lead to secondary elevation in tricuspid regurgitant jet velocity (TRV) and exercise intolerance, independent of pulmonary artery hypertension. Albuminuria is an early manifestation of sickle nephropathy. Albuminuria has been correlated with echocardiography-estimated pulmonary hypertension using TRV as a surrogate measure. Whether the sickle cardiomyopathy correlates with nephropathy is unknown. Design/Method: Echocardiograms were performed in individuals with SCA (SS and Sβ0-thalassemia) participating in a clinical trial of losartan for sickle nephropathy. We analyzed baseline (pre-losartan) results and correlated the cardiac phenotype with urine albumin-to-creatinine ratio (UACR), 6-minute walk distance (6MWD) and hematological markers. Albuminuria was defined as UACR ≥ 30 mg/g. Results: Thirty-six SCA patients were included (mean age 24.1y; 53% female). Fifteen had normal UACR (mean±SEM 9.2±1.5 mg/g) while 21 patients had albuminuria (UACR 373±87 mg/g). Patients with albuminuria had worse diastolic function indicated by the early-to-late ratio of mitral inflow velocities, E/A (1.81±0.1 vs 2.3±0.1, P=0.018), and septal annular velocities, e’/a’ (1.5±0.2 vs 2.4±0.2, P<0.001), and significantly larger LA volumes (57.2±3.1 vs 38.9±3.7 ml, P<0.001). Systolic function was normal and similar in both groups (shortening fraction 36.9±2% vs 36.7±1.5%, P=0.94). Patients with albuminuria had significantly lower hemoglobin (8.3±0.3 vs 9.2±0.3 g/dL, P=0.04); however, there was no difference in TRV, LV mass, LV diameter or reticulocyte count between groups. 6MWD correlated significantly with the diastolic measures E/A and septal e’/a’ (P=0.013 and P=0.015, respectively). Patients with albuminuria had significantly shorter 6MWD (1182±78 vs 1472±86 ft, P=0.018). Abstract source