Echocardiographic features and behavior of cardiac structural abnormalities in mucopolysaccharidosis

Funding Acknowledgements

Type of funding sources: None.

Mucopolysaccharidosis (MPS) is a rare genetic lysosomal storage disorder with a wide variability of phenotype. A systematic descriptive study dealing with the echocardiographic (E) features of valvular involvement and their evolution over the time in adolescent and adult patients, whose number is growing up in adult echocardiographic laboratory, is lacking in the medical literature.

Purpose

To detect the E features of valvular involvement and their evolution in adolescent and adult patients.

Method

Study design: observational descriptive retrospective. Study group: 142 E studies in 17 adolescent and adult patients with diagnosis of MPS from 2001 until 2020. Mitral (M), aortic (A), tricuspid (T) valves (V) E features (thickness, mobility, calcification, and function), their evolution over the time and the behaviour with Enzyme replacement therapy (ERT) or bone marrow transplant (BMT) were assessed.

Result

52% male, mean age 21 yrs ranges 16 to 48 yrs. 5% of the patient had MPS type I, 11% MPS type II, 29% MPS type IV, and 52% MPS type VI. 70% received ERT and 11% BMT.

In the severe case all the valves were involved (panel A, B, C; white arrows point to valve leaflets; yellow arrows MV apparatus) the whole MV apparatus was involved since the earlier stage and in the latest stage the calcification was massive (panel C). The predominant valvular dysfunction was the regurgitation followed by mixed disorder while the most frequent severe lesion was the stenosis; the echocardiographic pattern differs from the classical hockey stick appearance of the early phase of rheumatic MV and the thickening is different from the myxomatous MV for the reduced mobility and the presence of calcification. The reduced mobility of the TV (panel C) also differs from the Loeffler syndrome because of the restriction of the leaflets and the association with thickening and calcification. Under treatment, the MV thickening was found to have a slow progression of less than 1 mm yearly in 61% cases.

Conclusion

Our results showed that all the valves are affected mainly the MV; the echocardiographic pattern of MPS, different from other valvular diseases of adolescent and adult age, can help in avoiding misdiagnose. Our observations also suggest that the cardiac involvement show slow rate of progression after the initiation of the therapy. Further studies are required to confirm our results.

Type of valve % of valve thickness % of reduced mobility % calcification diffuse % valve lesion Mitral valve 88% 65% 47% 75% Aortic valve 76% 23% 41% 57% Tricuspid valve 82% 47% 17% 52% Abstract Figure. Echocardiographic features