Arrhythmias in MELAS syndrome

With interest we read the article by Thomas et al. about a 44 year old female with MELAS syndrome due to the m.3243ANG mutation, which manifested cardiologically as hypertrophic cardiomyopathy and episodes of supraventricular tachycardia requiring atenolol [1]. We have the following comments and concerns. MELAS may be associated with sudden cardiac death [2]. Did the authors consider implantation of a loop-recoder to monitor if there were also ventricular arrhythmias requiring implantation of an ICD? The authors describe hypertrophic cardiomyopathy as progressive [1]. What was the systolic function and wall thickness at the last follow-up? Figure 1B suggests that there is noncompaction of the left ventricular myocardium [1]. Did the authors look for this unclassified cardiomyopathy, which may occur in addition to hypertrophic cardiomyopathy, goes frequently along with late gadolinium enhancement [3], and is most frequently associated withmitochondrial disorders? [4] A heteroplasmy rate of 25% of the m.3243ANG mutation is low. In which tissue was it determined? Blood, muscle, saliva, or urine? Were other tissues investigated for the heteroplasmy rate as well? Was a muscle biopsy carried out? Recurrent stroke-like episodes (SLEs) are reported during the 11 years since diagnosis [1], which are a clinical manifestation of cerebral stroke-like lesions [5]. How many SLEs did the patient experience,