Laronidase replacement therapy and left ventricular function in mucopolysaccharidosis I.

We assessed the effects of long-term laronidase replacement therapy (LRT) on the left ventricular (LV) function of a 52-year-old adult woman with mucopolysaccharidosis I (MPS I). The urinary uronic acid concentration significantly decreased by 78.7% (from 75 to 16 mg/g creatinine) after LRT; thereafter, estimated LV weight as assessed by two-dimensional (2D) echocardiography significantly decreased by 33.3% (from 189 to 126 g). Although systolic LV function of the ejection fraction as assessed by 2D echocardiogram did not change after LRT, the diastolic LV function parameters of the deceleration time (DcT) and the ratio of early (E) to late (A) ventricular filling velocities (E/A ratio) significantly improved. The DcT significantly decreased from 355 to 300 ms and the E/A ratio significantly decreased from 1.8 to 0.98. These diastolic parameters were normalized. In the contraction synchrony assessed by 2D speckle tracking imaging, the maximum time delay of contraction decreased from 148 to 14 ms. In addition, the LV weight significantly correlated with the E/A ratio (p < 0.001, r = 0.63), DcT (p < 0.05, r = 0.48), and contraction synchrony (p < 0.001, r = 0.61), respectively. This is the first study to report that LRT significantly improves diastolic LV function and contraction synchrony in a patient with MPS I.