Systematic review of cardiac electrical disease in Kearns-Sayre syndrome and mitochondrial cytopathy

- Mitochondrial disease was initially thought to be a rare disorder.
- Prevalence studies have now confirmed that the frequency of mtDNA mutations amongst 'healthy' or oligo-symptomatic subjects is probably 1 in 200 to 250 persons.
- The review article looks at the current challenges in the management of cardiac electrical disease in mitochondrial disease and the role for cardiac magnetic resonance (CMRI) for identifying subclinical cardiac involvement and whether defibrillator implantation may be preferable to pacemaker implantation in some patients with cardiac conduction disease.
- We propose that the patients with structurally normal hearts on transthoracic echocardiography may have subclinical disease only detectable by CMRI and that due to the potential for rapid and unexpected development of heart block and ventricular arrhythmia, routine screening ECG's should as a minimum be carried out every 6 months.

Kearns-Sayre syndrome (KSS) is a mitochondrial disorder characterised by onset before the age of 20 years, progressive external ophthalmoplegia, and pigmentary retinopathy, accompanied by either cardiac conduction defects, elevated cerebrospinal fluid protein or cerebellar ataxia. 50% of patients with KSS develop cardiac complications. The most common cardiac manifestation is conduction disease which may progress to complete atrioventricular block or bradycardia-related polymorphic ventricular tachycardia (PMVT).The management of cardiac electrical disease associated with KSS and mitochondrial cytopathy is systematically reviewed including the case of a 23 year-old female patient with KSS who developed a constellation of cardiac arrhythmias including rapidly progressive conduction system disease and monomorphic ventricular tachycardia with myocardial scarring. The emerging role of cardiac magnetic resonance imaging (CMR) in detecting subclinical cardiac involvement is also highlighted. This review illustrates the need for cardiologists to be informed about this rare but emerging condition.