LAUSR

I read the letter by Dr. Finsterer with a great interest [1], but I must say I am pretty much concerned about wrong messages this letter sends to the readership and the way it was written. It is unusual that Dr. Finsterer did not mention any of the positive sides of our paper since the literature data on heart involvement in DM2 are pretty rare. It is also unusual that Dr. Finsterer in his letter did not cite any reference about DM2. In the following rows, I will try to respond on the aforementioned criticisms of our paper point by point. Dr. Finsterer wrote that one of the limitations of our study was that CCTG repeat lengths had not been provided. The most commonly used methods to diagnose DM2 today do not provide us with the number of CCTG repeats and this number was not reported neither in the major study on the heart involvement in DM2 [2] nor in the majority of other studies on other DM2 topics. I must emphasize that CCTG expansions in DM2 are extremely unstable; they change with age and differ within different tissues in the same person [3]. Interestingly, Dr. Finsterer himself wrote a case report of patient with 500–9500 CCTG repeats and another case of patient with more than 300 repeats not characterizing precise range. So, the question is what CCTG repeat length to correlate with cardiac defects: progenitor, modal or the largest allele, alleles from the white blood cells or the heart muscle (which is really hard to obtain). Furthermore, unlike in DM1, there is no clear association between the length of the CCTG expansion and the clinical severity [3] so we do not expect association between CCTG repeats and cardiac impairments. We agree that the shortcoming of our study is an absence of the follow-up data. Longitudinal study would be of great interest for all those who diagnose and treat DM2 patients and this will be our next step in investigating heart involvement in DM2. Also, data on cardiac therapy are also important and will be provided. It is true that modern imaging methods are certainly more sensitive in diagnosis of heart fibrosis and other cardiac structural defects. However, the aim of our study was not to use experimental methods, but to obtain data of routine cardiac assessments in DM2. We mentioned in our paper that importance of non-routine cardiac tests (such as magnetic resonance imaging (MRI), focal fibrosis imaging, magnetic spectroscopy, and more specific echocardiographic methods) is still not completely known [4]. Recently published recommendations for adults with DM2 suggest cardiac symptom assessments and standard ECG, while echocardiography, 24-Holter ECG, and electrophysiology should be considered only in some patients [3]. Heart MRI and loop recorders are not mentioned in these recommendations and they still have no defined role in DM2 assessment. Mentioning left ventricular hypertrabeculation (LVHT) in DM2 by Dr. Finsterer is at least surprising. LVHT has not been reported in DM2 so far. All the papers on this issue in myotonic dystrophy were written by Dr. Finsterer, but in DM1, not in DM2. So, I would kindly suggest Dr. Finsterer to conduct a research on a larger group of Austrian DM2 patients regarding LVHT. Austria is located in the Central Europe where DM2 is really frequent [5]. It is surprising that Austria does not have its own DM2 registry [5] and it is also unusual that all DM2 papers published by Dr. Finsterer are actually case reports. Thus, I would kindly ask Dr. Finsterer, who has a great experience in diagnosing and treating cardiac impairments in neuromuscular disorders, to conduct a larger prospective research of cardiac affection in DM2. This would be beneficial for of all us who treat DM2 patients and we will be ready to positively criticize this work. * Stojan Peric [email protected]