Cardiac disease in Kearns-Sayre syndrome requires comprehensive management

Mitochondrial Myopathy in a 21-Year-Old Man Presenting With Bilateral Lower Extremity Weakness and Swelling

Bilateral lower extremity weakness and swelling can have several causes. Although often underdiagnosed, mitochondrial myopathy is more prevalent in the general population than more commonly suspected diseases, such as Guillain-Barre syndrome. The clinical manifestations of mitochondrial disease can be broadly classified into 3 categories: chronic progressive external ophthalmoplegia, skeletal muscle-central nervous system syndromes, or pure myopathy. Cardiac abnormalities occur in 30% to 32% of cases, mostly in the form of hypertrophic cardiomyopathy, dilated cardiomyopathy, or conduction abnormalities. We report a case of a 21-year-old student who developed bilateral lower limb weakness, pain, and swelling diagnosed with mitochondrial myopathy on muscle biopsy. Initial laboratory tests revealed elevated creatinine kinase, brain natriuretic peptide, troponin, myoglobin, and lactic acid and reduced serum bicarbonate. Cardiac workup revealed systolic heart failure with a reduced ejection fraction. Endomyocardial biopsy revealed punctate foci of lymphocytic myocarditis. However, cardiac magnetic resonance imaging did not reveal either myocarditis or an infiltrative cardiac disease. An extensive autoimmune and infection work-up was negative. A muscle biopsy from the patient's rectus femoris revealed scattered ragged-blue fibers (stained with NADH dehydrogenase), scattered ragged-red fibers on modified Gomori trichrome stain, and cytochrome-c oxidase negative fibers with increased perimysial and endomysial connective tissue, consistent with active and chronic primary mitochondrial myopathy. The patient was treated successfully with furosemide, metoprolol, and methylprednisolone. Adult-onset mitochondrial myopathy is a rare clinical disorder, and our experience stresses the importance of using an inter-disciplinary team approach to diagnose uncommon clinical disorders with widely variable multisystem involvement.

Ventricular arrhythmias in Kearns-Sayre syndrome: A cohort study using the National Inpatient Sample database 2016-2019

BACKGROUND

Degeneration of the cardiac conduction system resulting in complete heart block (CHB), ventricular arrhythmias (VA), and sudden cardiac death (SCD) is recognized in patients with Kearns-Sayre syndrome (KSS) and is potentially preventable with permanent pacemaker (PPM) implantation. However, other mechanisms for SCD have been proposed, and the efficacy of implanting a defibrillator instead of PPM remains to be investigated.

METHODS

We utilized the National Inpatient Sample (NIS) database 2016-2019 to investigate the risk of VA or dysrhythmic cardiac arrest (dCA) in KSS patients. We compared the outcomes of KSS to myotonic dystrophy (MD), a more common genetic disorder with similar clinical cardiac features and course.

RESULTS

We identified 640 admissions for KSS. VA or dCA were lower in admissions for KSS than MD patients (2.3% vs. 4.5%, p = .009). Device implantation differed between study groups. Approximately, 70% of cases with KSS and conduction abnormalities had pacemaker (± defibrillator) on hospital discharge, compared to 35% in MD. Conduction abnormalities were associated with higher rates of VA or dCA in both study groups. None of the admissions for KSS patients who developed VA or dCA had a pacemaker, and all of them had conduction abnormalities. One-third of admissions for MD patients who developed VA or dCA had a device already implanted prior to the event.

CONCLUSION

Despite its effectiveness in preventing VA, PPM remains underutilized in patients with KSS or MD who have conduction abnormalities. PPM alone do not fully prevent VA in MD patients; therefore, addition of defibrillator capacity might be necessary.

Kearns Sayre syndrome: a rare etiology of complete atrioventricular block in children (case report)

Kearns Sayre syndrome is a rare mitochondrial abnormality first described in 1958, characterized by a triad associating progressive external ophthalmoplegia, ptosis, and pigmentary retinopathy with progressive alteration of cardiac conduction, which determines the vital prognosis of this entity. Here we report the case of a 13-year-old child of consanguineous parents who consults for recurrent syncope. The clinical exam found bilateral ptosis with complete atrioventricular block on electrocardiogram. The ophthalmological exam found pigmentary retinopathy. The patient underwent successful implantation of a double chamber pacemaker within 24 hours of admission, with an uneventful postoperative course. This case report highlights the interest of systematically assessing cardiac complications in children with mitochondrial disease such as Kearns Sayre syndrome, especially since cardiac involvement is the major prognostic factor in this disease.