Identifying evidence of cardio-renal syndrome in patients with Duchenne muscular dystrophy using cystatin C.

Patients with Duchenne muscular dystrophy (DMD) develop dilated cardiomyopathy and are at risk for kidney injury. Creatinine based estimated glomerular filtration rate (eGFR) is limited by low muscle mass with low serum creatinine levels in DMD. We assessed the relationship between cardiac function, modified Schwartz eGFR and cystatin C eGFR in patients with DMD. Ninety-three patients with DMD were screened for renal dysfunction in an outpatient neuromuscular clinic. Patients with new nephrotoxic medications, recent hospitalization or decompensated heart failure were excluded from the analysis. Eleven (12%) patients had evidence of renal dysfunction identified by cystatin C eGFR, while no patients had renal dysfunction by Schwartz eGFR. There was no significant correlation between cystatin C eGFR and age (r = -0.2, p = 0.11), prednisone dose (r = 0.06, p = 0.89) or deflazacort dose (r = -0.01, p = 0.63). There was a significant correlation between left ventricular ejection fraction and cystatin C GFR among patients with chronic left ventricular dysfunction (r = 0.46, p < 0.01), but not normal function (r = -0.07, p = 0.77). There was no significant correlation between left ventricular ejection fraction and Schwartz eGFR among patients with (r = 0.07, p = 0.59) or without (r = -0.27, p = 0.07) chronic left ventricular dysfunction. Cystatin C eGFR correlates with cardiac dysfunction in patients with DMD, thus providing novel evidence of cardio-renal syndrome in this population. Routine monitoring of renal function is recommended in patients with DMD.