Cardiac phenotype determines survival in Duchenne muscular dystrophy.

OBJECTIVE

To identify determinants of survival by comparing cardiopulmonary function in two patient groups: prolonged survivors of Duchenne muscular dystrophy (DMD) versus DMD patients who experienced early death (ED).

METHODS

Retrospective chart review of our DMD patients from 1999 to 2013. Prolonged Survival (PS) was defined as alive and ≥30 years old. Early death (ED) was defined as death at < 30 years old.

EXCLUSION CRITERIA: steroid therapy.

RESULTS

Eleven patients met criteria for PS and 14 patients for ED (mean age ± SD: 34.3 ± 4.3 years vs. 21.7 ± 3.8 years, respectively; P < 0.001). Pulmonary function was better in the ED patients: all PS patients had a vital capacity of 0 ml (n = 11) versus 23% (3/13) of the ED patients (P < 0.001). Thirteen of 14 ED patients and all PS patients received assisted ventilation. Heart function was worse in the ED patients: ejection fraction (EF) was 42.2 ± 14.2% in the PS patients (n = 11) versus 29.2 ± 14.1% in the ED patients (n = 13; P = 0.035). Dilated cardiomyopathy was present in 36% (4/11) of PS patients versus 78% (11/14) of ED patients (P =0.048). Among ED patients, 57% (8/14) died from progressive cardiomyopathy.

CONCLUSION

In our study group, good heart function was a pre-condition for PS and poor heart function was the primary cause of early death. Our results suggest that, when DMD patients are treated with assisted ventilation, heart function is the main determinant of their survival.