Effects of enzyme replacement therapy on cardiac function in classic infantile Pompe disease

OBJECTIVE

Patients with classic infantile Pompe disease are born with a hypertrophic cardiomyopathy, which resolves after treatment with Enzyme replacement therapy (ERT). We aimed to assess potential deterioration of cardiac function over time using myocardial deformation analysis.

METHODS

Twenty-seven patients treated with ERT were included. Cardiac function was assessed at regular time intervals (before and after start with ERT) using conventional echocardiography and myocardial deformation analysis. Separate linear mixed effect models were used to asses temporal changes within the first year and the long-term follow-up period. Echocardiograms of 103 healthy children served as controls.

RESULTS

A total of 192 echocardiograms were analyzed. Median follow-up was 9.9 years (IQR: 7.5-16.3). Mean LVMI before start of ERT was increased 292.3 g/m² (95% CI: 202.8-381.8, mean Z-score + 7.6) and normalized after 1 year of ERT 87.3 g/m² (CI: 67.5-107.1, mean Z-score + 0.8, p < 0.001). Mean shortening fraction was within normal limits before start of ERT, up to 22 years of follow-up. Cardiac function measured by RV/LV longitudinal, and circumferential strain was diminished before start of ERT, but normalized (<-16%) within 1 year after start of ERT, and all remained within normal limits during follow-up. Only LV circumferential strain gradually worsened in Pompe patients (+0.24%/year) during follow-up compared to controls. LV longitudinal strain was diminished in Pompe patients, but did not change significantly over time compared to controls.

CONCLUSION

Cardiac function, measured using myocardial deformation analysis, normalizes after start of ERT, and seems to remain stable over a median follow-up period of 9.9 years.

Improvement in Cardiac Function With Enzyme Replacement Therapy in a Patient With Infantile-Onset Pompe Disease

Background

Pompe disease is a lysosomal storage disorder that results from an inborn error of metabolism involving abnormal glycogen storage. Infantile-onset Pompe disease is the most severe phenotype, and enzyme replacement therapy with alglucosidase alfa (Lumizyme) improves medical and functional outcomes in patients with infantile-onset Pompe disease.

Case Report

We report the case of a patient with infantile-onset Pompe disease who presented with severe hypertrophic cardiomyopathy, systolic and diastolic cardiac dysfunction, and hypotonia. She experienced significant improvement in cardiac systolic function while receiving enzyme replacement therapy.

Conclusion

Typically, patients with infantile-onset Pompe disease and severe hypertrophic cardiomyopathy are not as responsive to enzyme replacement therapy as patients with mild or no hypertrophic cardiomyopathy. We demonstrated the efficacy of enzyme replacement therapy in a patient with severe hypertrophic cardiomyopathy.

Cardiac outcome in classic infantile Pompe disease after 13 years of treatment with recombinant human acid alpha-glucosidase

BACKGROUND

Cardiac failure is the main cause of death in untreated classic infantile Pompe disease, an inheritable metabolic myopathy characterized by progressive hypertrophic cardiomyopathy. Since the introduction of enzyme replacement therapy (ERT), survival has increased significantly due to reduced cardiac hypertrophy and improved cardiac function. However, little is known about ERT's long-term effects on the heart.

METHODS

Fourteen patients were included in this prospective study. Cardiac dimensions, function, conduction and rhythm disturbances were evaluated at baseline and at regular intervals thereafter.

RESULTS

Treatment duration ranged from 1.1 to 13.9 years (median 4.8 years). At baseline, all patients had increased left ventricular mass index (LVMI) (median LVMI 226 g/m², range 98 to 599 g/m², Z-score median 7, range 2.4-12.4). During the first four weeks, LVMI continued to increase in six patients. Normalization of LVMI was observed in 13 patients (median 30 weeks; range 3 to 660 weeks). After clinical deterioration, LVMI increased again slightly in one patient. At baseline, PR interval was shortened in all patients; it normalized in only three. A delta-wave pattern on ECG was seen in six patients and resulted in documented periods of supraventricular tachycardias (SVTs) in three patients, two of whom required medication and/or ablation. One patient had severe bradycardia (35 beats/min).

CONCLUSION

This study shows that ERT significantly reduced LVMI, and sustained this effect over a period of 13.9 years. The risk for rhythm disturbances remains. Regular cardiac evaluations should be continued, also after initially good response to ERT.