Author’s reply

Abstract

We greatly appreciate Dr Josef Finsterer for the thoughtful suggestions and comments. Firstly, we agree with Dr Finsterer that the chance of developing takotsubo syndrome (TTS) is increased in individuals with dilated cardiomyopathy (dCMP) or left ventricular noncompaction (LVNC). The high prevalence of cardiac involvement in Duchenne muscular dystrophy (DMD) presenting as dCMP [[1]Kamdar F. Garry D.J. Dystrophin-deficient cardiomyopathy.J Am Coll Cardiol. 2016; 67: 2533-2546Crossref PubMed Scopus (191) Google Scholar] and also LVNC [[2]Statile C.J. Taylor M.D. Mazur W. Cripe L.H. King E. Pratt J. et al.Left ventricular noncompaction in Duchenne muscular dystrophy.J Cardiovasc Magn Reson. 2013; 15: 67Crossref PubMed Scopus (32) Google Scholar] may predispose these patients to TTS. However, in our patient [[3]Saprungruang A. Vithessonthi K. Vorasettakarnkij Y. Lertsapcharoen P. Khongphatthanayothin A. Recurrent Takotsubo syndrome in a boy with Duchenne muscular dystrophy: a case report.J Cardiol Cases. 2019; 20: 14-19Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar], the cardiac magnetic resonance imaaging (CMR) up until the last follow-up revealed low normal left ventricular (LV) size with slightly low normal LV systolic function without overt dCPM nor LVNC. Our patient developed mild but progressive proximal muscle weakness at around 18 months and was diagnosed with DMD 3 months prior to the first TTS episode. He did not receive any steroid or medication for DMD. He had no previous spinal operation for his muscle weakness. He had never experienced seizure or abnormal neurologic symptoms, so cerebral imaging and electroencephalography recording were not done. He had no respiratory problem at the time of both episodes of TTS. The patient developed TTS while watching television on the first episode and while playing a video game which he claimed that he was very excited about on both episodes although we did not enquire into the detail of the show or game he played. Both of the TTS episodes resolved spontaneously without signs or symptoms of overt heart failure and did not require treatment. The second comment was about CMR findings. From our case description, our patient exhibited late-gadolinium enhancement (LGE) in subepicardial area from basal-to-apical lateral wall which was a typical finding in DMD [[4]Hor K.N. Mah M.L. Johnston P. Cripe T.P. Cripe L.H. Advances in the diagnosis and management of cardiomyopathy in Duchenne muscular dystrophy.Neuromuscul Disord. 2018; 28: 711-716Abstract Full Text Full Text PDF Scopus (24) Google Scholar]. The subepicardial enhancement was probably the result of subepicardial fibrosis. He did not demonstrate LGE in mid-endocardial area which was found in myocarditis or acute myocardial infarction. Finally, there were no data on either pro-B-type natriuretic peptide (BNP) or urine catecholamine level as these tests were not routinely done in our patient with TTS. Although the serum BNP or N-terminal-proBNP levels are always elevated [[5]Ahmed K.A. Madhavan M. Prasad A. Brain natriuretic peptide in apical ballooning syndrome (Takotsubo/stress cardiomyopathy): comparison with acute myocardial infarction.Coron Artery Dis. 2012; 23: 259-264Crossref PubMed Scopus (47) Google Scholar] and were recently included in new diagnostic criteria for TTS proposed by the European Society of Cardiology in 2016 [[6]Lyon A.R. Bossone E. Schneider B. Sechtem U. Citro R. Underwood S.R. et al.Current state of knowledge on takotsubo syndrome: a position statement from the taskforce on takotsubo syndrome of the heart failure association of the european society of cardiology.Eur J Heart Fail. 2016; 18: 8-27Crossref PubMed Scopus (629) Google Scholar], the evidence that supports the superiority of the biomarkers compared with cardiac troponin are still limited. Similarly, there are discrepancies in the studies of plasma catecholamine levels in patients with TTS. Many studies reported that majority of patients with TTS had normal or mildly elevated plasma catecholamine level while some other studies reported extremely high levels [[7]Y-Hassan S. Henareh L. Plasma catecholamine levels in patients with takotsubo syndrome: implications for the pathogenesis of the disease.Int J Cardiol. 2015; 181: 35-38Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar].