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• Is subclinical myocardial affection in Duchenne muscular dystrophy detectable?
  josef finsterer
  Published on: 23 November 2015

• Published on: 23 November 2015

  Is subclinical myocardial affection in Duchenne muscular dystrophy detectable?

  • josef finsterer, neurologist
  • Other Contributors:
    • claudia stöllberger

  Dear Editor,

  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 [1]. The findings raise the following concerns:

  How to explain the d...

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  Dear Editor,

  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 [1]. The findings raise the following concerns:

  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 [2]. It is well known that DMD patients frequently present with sinustachycardia [3]. 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 [4]. 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 [2]. Recently left ventricular hypertrabeculation has been first described in a DMD patient [5]. 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 relevance.

  References

  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 2005;94:465-8.

  3 Kirchmann C, Kececioglu D, Korinthenberg R, Dittrich S. Echocardiographic and electrocardiographic findings of cardiomyopathy in Duchenne and Becker-Kiener muscular dystrophies. Pediatr Cardiol 2005;26:66-72.

  4 Nigro G, Comi LI, Politano L, Bain RJ. The incidence and evolution of cardiomyopathy in Duchenne muscular dystrophy. Int J Cardiol 1990;26:271-7.

  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 Cardiol 2005;60:445-8.

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  Conflict of Interest:
  None declared.

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