Background: Nephropathic cystinosis is a rare autosomal recessive lysosomal storage disorder that initially affects the kidney progressing to multi-organ failure due to accumulation of cystine in all tissue compartments.
Objective: The main objective of this study is the evaluation of cardiac function in cystinosis patients using non-conventional echocardiographic modalities like pulsed wave tissue Doppler imaging (PW-TDI) and 2D speckle tracking echocardiography (2D-STE).
Methods: This is a case control study conducted on fifteen patients with cystinosis and 15 normal controls. Echocardiography was done for all participants and PW-TDI was performed for measurement of S', E', A' velocities and myocardial performance index (MPI) at basal parts of septal, left ventricle (LV), and right ventricle (RV) free walls. 2D-STE was done for evaluation of global longitudinal strain (GLS), global circumferential strain (GCS), and global radial strain (GRS) of LV. Mitral E and A velocities and tricuspid annular plane systolic excursion (TAPSE) were also measured.
Results: The GLS, GRS, and S' velocity at basal septum and LV lateral wall were significantly lower in patients denoting LV systolic dysfunction (p = 0.005, p < 0.0001, p = 0.001, p = 0.006, respectively), while E/E' were significantly higher in patients group denoting LV diastolic dysfunction (p < 0.001). For RV function, TAPSE, S', and E' velocity were significantly lower in patients group (p 0.013, p < 0.01, p = 0.05, respectively) indicating RV systolic and diastolic dysfunction. The TDI-derived MPI for both LV and RV were significantly higher in patients group (p < 0.0001, p < 0.01, respectively) indicating both ventricular systolic and diastolic dysfunction. For prediction of cardiac dysfunction among patients, the receiver operating characteristic (ROC) curve showed that GRS ≤ 29% had sensitivity 93.3% and specificity 100%, GLS > - 20.1% had sensitivity 66.7% and specificity 93.3%, LV-E/E' >7.87 had sensitivity 73.3% and specificity 93.3%, and MPI-LV > 0.36 had sensitivity 100% and specificity 93.3% while MPI-RV > 0.29 had sensitivity 80% and specificity 93.3% and TAPSE ≤ 19 mm had sensitivity 80% and specificity 73.3%.
Conclusions: Patients with cystinosis have significant both left and right ventricular dysfunction, which can be better evaluated using the non-conventional echocardiographic modalities like TDI and 2D-STE for early detection of subtle cardiac dysfunction.
Keywords: 2D-STE; Cystinosis; TDI; Ventricular dysfunction.