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With interest we read the article by Giatrakos et al. on tissue
velocity (TV) and radial strain rate (RSR) imaging in 56 Duchenne muscular
dystrophy (DMD) patients. The authors found that TV and RSR were reduced
in systole and early diastole in DMD boys as compared to controls and
predicted an adverse outcome of these patients . The findings raise the
How to explain the d...
How to explain the discrepancy between the number of investigated patients
between the abstract (n=48) and the method and result section (n=56)? Were
actually 48 or 56 patients investigated?
Was there any age-dependency of the measured parameters? Did older boys
show more abnormal function than younger ones? How to explain the
discrepancy between the man age of 8.8 years at baseline and the mean age
of 16.5 years of the seven boys with left ventricular dysfunction,
although follow-up time was only 3 years? Were these seven boys the oldest
of the cohort?
The authors speculate that abnormal RSR and TV imaging in the posterior
wall may be attributed to fibrous and fatty tissue replacement of
myocardiocytes. In the case of myocardial fibrosis it is surprising that
transthoracic echocardiography was normal and did not even show wall
motion abnormalities or abnormal texture. In addition to myocardial
fibrosis they explain their findings by delayed focal activation and
conduction delay. If this is the case, one would expect abnormal instead
of normal ECGs. Which is the evidence that the posterior wall is most
affected by the dystrophic process? Midwall myocardial fibrosis occurs
diffusely distributed in all segments of the myocardium .
It is well known that DMD patients frequently present with
sinustachycardia . Was heart rate different between patients and
controls and how did heart rate influence the measured parameters?
How many patients had thorax deformities and to which degree did it
influence the RSR values?
Were the included patients investigated by ECG only once or at each of the
6 month follow-ups? Usually, cardiac abnormalities deteriorate during the
disease course and can be detected on repeated follow-ups. Was a FS
<29% the only cardiac abnormality at the 3-year follow-up or were other
cardiac abnormalities additionally detected? Which were the results of RSR
and VR imaging after three years?
ECG abnormalities have been reported to occur already before age of 5y
. How do the authors explain that all their patients had normal ECG
although they had a mean age of already 8.8y?
Did the included patients also undergo AECGs, which may more likely show
abnormal recordings compared to routine ECGs? Was the AECG abnormal in any
of the included patients?
Did the patients undergo also cardiac MRI? It has been shown that serial
MRI investigations of dystrophic hearts can nicely document the
progression of fibrous tissue replacement .
Recently left ventricular hypertrabeculation has been first described in a
DMD patient . Did the authors look for LVHT and did they find this
myocardial abnormality in any of their patients?
Which was the cause of death in the 3 patients and why were so many boys
lost to follow-up?
Which are the clinical implications of their findings? Should the treating
physicians start with ACE inhibitor therapy if TV and RSR imaging
parameters are reduced? How many patients received a cardiac medication
upon TV and RSR imaging?
Overall, the pathogenetic background of the reported findings remains
unexplained. The clinical relevance of the findings is not clear. It is
also unclear why the transthoracic echocardiography was normal despite the
marked abnormalities on RSR and VR imaging. The method needs to be
compared at least with cardiac MRI before final assessment of its clinical
1 Giatrakos N, Kinali M, Stephens DA, Dawson D, Muntoni F,
Nihoyannopoulos P. Cardiac tissue velocities and strain rate in the early
detection of myocardial dysfunction of asymptomatic boys with Duchenne
muscular dystrophy: relation to clinical outcome. Heart. 2006;(in press)
2 Suselbeck T, Haghi D, Neff W, Borggrefe M, Papavassiliu T. Midwall
myocardial fibrosis in Becker-Kiener muscular dystrophy. Z Kardiol
3 Kirchmann C, Kececioglu D, Korinthenberg R, Dittrich S.
Echocardiographic and electrocardiographic findings of cardiomyopathy in
Duchenne and Becker-Kiener muscular dystrophies. Pediatr Cardiol
4 Nigro G, Comi LI, Politano L, Bain RJ. The incidence and evolution
of cardiomyopathy in Duchenne muscular dystrophy. Int J Cardiol
5 Finsterer J, Gelpi E, Stollberger C. Left ventricular
hypertrabeculation/noncompaction as a cardiac manifestation of Duchenne
muscular dystrophy under non-invasive positive-pressure ventilation. Acta