The association between cardiac involvement and long-term clinical outcomes in patients with Duchenne muscular dystrophy

Abstract

Aims: Despite advances in contemporary cardiopulmonary therapies, cardiomyopathy remains the leading cause of death in patients with Duchenne muscular dystrophy (DMD). Also, the long-term clinical outcomes of patients with DMD and cardiomyopathy is unknown. This study investigated long-term clinical outcomes and their associated factors in patients with late-stage DMD.

Methods and results: A total of 116 patients with late-stage DMD (age > 15 years) were enrolled in this retrospective study. All enrolled patients were followed up at a single tertiary referral hospital. LV systolic dysfunction was dichotomously defined as reduced [left ventricular ejection fraction (LVEF) ≤ 40%] vs. preserved [>40%] based on the initial echocardiographic result. The primary endpoint was all-cause death. The secondary endpoint was a composite event defined as death or unexpected hospitalization due to cardiovascular reasons including chest pain, dyspnoea, and generalized oedema. The patients were divided into preserved (n = 84, 72.4%) and reduced LVEF groups (n = 32, 27.6%). The mean age was 20.8 ± 5.9 years, the mean disease duration, 8.8 ± 3.7 years, and the mean follow-up duration, 1708 ± 659 days. For primary endpoint, the reduced LVEF group showed a lower rate of overall survival (Reduced LVEF vs. Preserved LVEF; 81.3% vs. 98.8%, log-rank P = 0.005). In the multivariable Cox regression analysis, brain-natriuretic peptide (BNP) level (adjusted hazard ratio [HR] 1.088, 95% confidence interval [CI] 1.019-1.162, P = 0.011) and diuretic use (adjusted HR 9.279, 95%CI 1.651-52.148, P = 0.011) were significant predictors of all-cause death in patients with DMD. For the secondary endpoint, the reduced LVEF group had a lower rate of freedom from composite events than the preserved LVEF group (65.6% vs. 86.9%, log-rank P = 0.005). In the multivariable Cox regression analysis, BNP level (adjusted HR 1.057, 95%CI 1.005-1.112, P = 0.032) and diuretic use (adjusted HR 4.189, 95% CI 1.704-10.296, P = 0.002) were significant predictors of the composite event in patients with DMD.

Conclusions: Patients with DMD and reduced LVEF had worse clinical outcomes than those with preserved LVEF. BNP level and diuretic use were associated with adverse clinical outcomes in patients with late-stage DMD, irrespective of LVEF.

Keywords: Brain-natriuretic peptide; Diuretics; Duchenne muscular dystrophy; LV systolic dysfunction; Long-term clinical outcome.