Reduced Inotropic Reserve is Predictive of Further Degradation in Left Ventricular Ejection Fraction in Patients with Duchenne Muscular Dystrophy

AIMS: Duchenne muscular dystrophy (DMD), an inherited X-linked muscular disease, is associated with dilated cardiomyopathy that is responsible for death in 40% of patients. Our objective was to determine whether inotropic reserve is predictive of LV trend over time. METHODS AND RESULTS: A total of 69 DMD patients (age 12.2±2.3 years) were investigated. At baseline, LVEF and the presence of inotropic reserve (defined as an increase in LVEF >10% during dobutamine infusion) were investigated using radionuclide ventriculography. During follow-up (FU), LVEF was remeasured after a mean 29±19 months delay. In the whole population, mean LVEF was 58±8% at baseline and declined to 54±11% during FU (P =0.004). At baseline, 21 patients (30.4%) had LVEF <55% and 38 had no LV inotropic reserve. LVEF declined in the 38 patients (55.1%) without LV inotropic reserve (58±8% to 52±10%, P =0.001), and not in the other patients (58±8% to 57±11%, P =0.516) (P =0.042 for trends in LVEF between groups after adjustment for age, FU duration, and baseline LVEF). Fewer patients with vs. without inotropropic reserve at baseline show a depressed LVEF <55% during follow-up(35.5% vs. 63.2%, respectively, P =0.030). Similar findings were observed in the subgroups of patients with LVEF >45% or 55% at baseline. CONCLUSION: Inotropic reserve assessment allows the distinction of DMD patients who will vs. those who will not show a deterioration in LVEF, thus offering a sensitive approach for delineating the presence and progression of cardiovascular disease in these patients.