Abstract 13810: Early Detection of Cardiomyopathy in the Patients with Duchenne Muscular Dystrophy by Endsystolic Wall Stress and Heart Rate
Duchenne Muscular Dystrophy (DMD) patients are known to develop irreversible dilated cardiomyopathy in their late teens that can frequently become a lethal event. However, the early detection of cardiomyopathy is usually challenging because of its insidious onset and their inability to address symptoms because of their sedentary life style due to progressive muscle wasting. Here, we introduced the concept of End Systolic Wall Stress Index (ESWSI) that is calculated by End-Systolic Wall Stress (ESWS) multiplied by heart rate (HR). Both ESWS and HR are known determinants of myocardial oxygen demands. We assessed the hypothesis that ESWSI serves as a sensitive marker of LV dysfunction in DMD patients. Three groups were studied: (1) Normal control (n = 17), (2) DMD with normal LV systolic performance (DMD-A: LVSF >30% and LVIDd < +2SD: n = 10), and (3) DMD with decreased LV systolic performance (DMD-B: LVSF < 28% or LVIDd > +2SD: n = 10). ESWS was calculated by using Laplace's law with measurement of LV diameter and LV wall thickness in end-systole by M-mode echocardiogram (LVIDs and LVWs, respectively) and simultaneous systolic blood pressure (SBP) measurement: ESWS = [SBP x LVIDs]/LVWs. Data were shown as mean ± SD. The patients’ ages were comparable in all 3 groups: (1) 12.7 ±2.9, (2), 11.8 ±2.7, and (3) 14.0 ±2.7. LVSF was (1) 37.0 ±3.2%, (2) 33.2 ±2.7%, and (3) 21.0 ±4.6%. ESWSI was significantly higher in DMD-A than in control despite normal LVFS in DMD-A (Figure). ESWSI showed linear increase as LVSF worsened, as shown as a stepwise increase in normal, DMD-A, and DMD-B groups. ESWSI may serve as a useful non-invasive marker of LV dysfunction when assessed with other echocardiographic parameters of LV function. In conclusion, ESWSI serves as a reliable marker of early LV dysfunction in DMD patients and the increase of ESWSI beyond normal range may indicate an early cardiomyopathic change that justifies early treatment.
- © 2011 by American Heart Association, Inc.