Cardiogenetics 2019; volume 9:8194

Non-ischemic scar underlines ventricular arrhythmias in Case Report Correspondence: Alessandro Zorzi, Kearns-Sayre A 44-year old male with KSS was Department of Cardiac, Thoracic, Vascular referred to our cardiology clinic four years and Public Health Sciences, University of Padova, via Giustiniani 2, 35100, Padova, syndrome before for palpitations. Serial 24-h ECG Italy. demonstrated frequent ventricular ectopic Tel.: +39.0498.212321. Stefano Figliozzi, Alessandro Zorzi, beats (VEBs) and non-sustained ventricular E-mail: [email protected] Martina Perazzolo Marra, tachycardia that persisted despite beta- Alessandro Ruocco, Sabino Iliceto, blockers therapy. There was no family his- Key words: Mitochondrial cardiomyopathy; Domenico Corrado, Chiara Calore tory of cardiac disease and his medications Kearns-Sayre syndrome; ventricular arrhyth- were carvedilol, ramipril and coenzyme Q- mias; imaging; cardiac magnetic resonance; Department of Cardiac, Thoracic, 10. Baseline electrocardiogram (ECG) non-ischemic scar. Vascular and Public Health Sciences, (Figure 1, panel A) and transthoracic University of Padova, Italy echocardiography were normal. A 12-lead Received for publication: 28 March 2019. Accepted for publication: 12 July 2019. 24-h ambulatory ECG monitoring recorded 2175 isolated VEBs, 35 couplets and a run Abstract This work is licensed under a Creative of nonsustained ventricular tachycardia of 5 Commons Attribution NonCommercial 4.0 Kearns-Sayre syndrome (KSS) is a rare beats with a right bundle branch License (CC BY-NC 4.0). mitochondrial disease in which cardiac block/superior axis pattern of the ectopic involvement has been associated with poor QRS, suggesting left ventricular free-wall ©Copyright: the Author(s), 2019 prognosis. Although the most common clin- origin (Figure 1, panel B). Frequent atrial Licensee PAGEPress, Italy ical manifestation is progressive conduction ectopic beats (1981 in 24 h) were also pres- Cardiogenetics 2019; 9:8194 doi:10.4081/cardiogenetics.2019.8194 system impairment, patients can suffer from ent, while there was no evidence of atri- ventricular arrhythmias. Yet, they show a oventricular block. Contrast-enhanced car- high prevalence of sudden cardiac death, diac magnetic resonance (CMR) revealed only whose etiopathological mechanism is not mid-wall late gadolinium enhancement tive biomarkers.6 Similar to our case, in 8 completely understood. Cardiac magnetic (LGE) in the basal-mid anterolateral and out of these 10 patients, myocardial resonance is a rising tool to detect subclini- inferolateral segments, consistent with a left involvement consisted of a mid-wall area of cal heart involvement in many heart dis- ventricular non-ischemic scar (Figureuse 1, LGE in the basal-mid lateral segments. eases and was recently able to detect non- panels C and D) in the absence of morpho- Interestingly, this LGE pattern was not ischemic scar, which is an arrhythmogenic functional abnormalities, myocardial edema found in other mitochondrial disorders with substrate, in patients affected by KSS. or fatty infiltration. The regional distribu- heart involvement. KSS is distinctively tion of the myocardial scar was consistent characterized by a high risk of SCD: with the plausible site of origin of VEBs. although atrioventricular block due to pro- gressive conduction system disease is tradi- Introduction tionally believed to be the cause, a number Kearns-Sayre syndrome (KSS) is a of patients died suddenly despite pacemaker 7 mitochondrial disease characterized by Discussion implantation. In these cases, myocardial onset before the age of 20 years, progres- Scar tissue is a well-known substrate for scar-related VAs may be a potential mecha- sive external ophthalmoplegia, pigmentary VEBs (which origin from surviving nism. According to this perspective, CMR retinopathy, elevated cerebrospinal fluid myocites interspersed among fibrous tissue should be strongly considered for detection protein and cerebellar ataxia.1 Cardiac or the scar borden-zone) and re-entrant sus- of cardiac involvement in KSS patients, involvement is more frequent in KSS than tained ventricular tachycardia in patients particularly in those with ventricular in other mitochondrial disorders, often in with cardiomyopathies.3 More recently, iso- arrhythmias, as it may help to identify con- the form of progressive conductionNon-commercial system lated left-ventricular myocardial scar with a cealed arrhythmogenic substrates. disease leading to bundle branch block and non-ischemic distribution has been recog- infra-Hissian atrioventricular block because nized as a substrate of apparently unex- the specialized cardiac conduction system plained VAs in patients with otherwise cells are particularly rich of mitochondria. structurally normal heart.4 Although these Conclusions Furthermore, patients with KSS show a lesions are traditionally considered the sign Although the most common clinical high risk of sudden cardiac death (SCD), of a healed myocarditis, left ventricular scar manifestation of KSS is progressive con- which is traditionally ascribed to atrioven- with a subepicardial/midmural (i.e. non- duction system impairment, patients can tricular block or torsades-de-pointes in the ischemic) distribution can be secondary to also suffer from VAs. Myocardial scar is an context of bradycardia-related QT-prolon- genetically-determined cardiac damage arrhythmic substrate that is frequently gation. On the other hand, ventricular such as in case of desmoplakin, phospho- demonstrated by CMR in the absence of arrhythmias (VAs) can also be observed, lamban or filamin-C gene-mutation.5 All echocardiographic or ECG abnormalities. although their etiopathological mechanism those conditions are characterized by a high Consequently, CMR may provide an incre- and clinical relevance remain to be elucidat- risk of SCD for ventricular tachyarrhyth- mental value for cardiac involvement iden- ed.2 We present the case of a patient affected mias unrelated to the degree of ventricular tification and risk stratification of patients by KSS with a long-standing history of VAs systolic dysfunction. with KSS. Prospective cohort studies are despite the absence of electrocardiogram A recent CMR study detected patholog- needed to evaluate the impact of myocardial (ECG) and electrocardiographic signs of ical findings in 10 out of 35 patients affect- scarring on indications to prophylactic ICD cardiac involvement. ed by KSS, despite normal ECG and nega- implantation even in the absence of myocar-

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Figure 1. Baseline electrocardiogram is normal (A). Nonsustained ventricular tachycardia recorded at 24-h ambulatory electrocardio- gram monitoring. A right bundle branch block/superior axis pattern of the ectopic QRS is evident (B). Contrast-enhanced cardiac mag- netic resonance reveals mid-wall late gadolinium enhancement of the left ventricle,use consistent with non-ischemic scar. Long axis (C) and basal short-axis (D) views show the involvement of the basal-mid segments of the anterolateral and inferolateral myocardial wall (arrows).

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