Reduced inotropic reserve is predictive of further degradation in left ventricular ejection fraction in patients with Duchenne muscular dystrophy

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AimsDuchenne 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 resultsA 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.ConclusionInotropic 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.

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