Torsades de pointes in a patient with Kearns-Sayre syndrome: a fortunate finding

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.

Arrhythmia prevalence and sudden death risk in adults with the m.3243A>G mitochondrial disorder

AIMS

To define the prevalence of non-sustained tachyarrhythmias and bradyarrhythmias in patients with the m.3243A>G mitochondrial genotype and a previously defined, profile, associated with 'high sudden-death risk'.

METHODS AND RESULTS

Patients at high risk of sudden death because of combinations of ventricular hypertrophy, mitochondrial encephalopathy, lactic acidosis and stroke-like episodes family phenotype, epilepsy or high mutation load, due to the m.3243A>G mutation, were identified from a mitochondrial cohort of 209 patients. All recruited had serial ECG and echo assessments previously according to schedule, had an ECG-loop recorder implanted and were followed for as long as the device allowed. Devices were programmed to detect non-sustained brady- or tachy-arrhythmias. This provided comprehensive rhythm surveillance and automatic downloads of all detections to a monitoring station for cardiology interpretation. Those with sinus tachycardia were treated with beta-blockers and those with ventricular hypertrophy received a beta-blocker and ACE-inhibitor combination.Nine consecutive patients, approached (37.2±3.9 years, seven males) and consented, were recruited. None died and no arrhythmias longer than 30s duration occurred during 3-year follow-up. Three patients reported palpitations but ECGs correlated with sinus rhythm. One manifest physiological, sinus pauses >3.5 s during sleep and another had one asymptomatic episode of non-sustained ventricular tachycardia.

CONCLUSIONS

Despite 'high-risk' features for sudden death, those studied had negligible prevalence of arrhythmias over prolonged follow-up. By implication, the myocardium in this genotype is not primarily arrhythmogenic. Arrhythmias may not explain sudden death in patients without Wolff-Parkinson-White or abnormal atrioventricular conduction or, it must require a confluence of other, dynamic, proarrhythmic factors to trigger them.

Kearns-Sayre Syndrome With Persistent Ventricular Tachycardia Refractory to Shocks and Medications

Cardiovascular conduction delay makes up part of the triad associated with Kearns-Sayre syndrome (KSS). Although there have been a few reported cases of prolonged Qtc and polymorphic ventricular tachycardia associated with this disease, despite the use of automatic implantable cardioverter defibrillators (AICD) for secondary prevention, some cases have been reported where the use of AICD did not help. We present a case of a 62-year-old male with KSS who came to the emergency department (ED) after two episodes of syncope. He already had an automatic AICD placed at the age of 34. Our patient had Qtc prolongation which is an unusual finding in KSS. He also had recurrent ventricular tachycardia (VT) refractory to medications and multiple shocks from his AICD, which progressed to a VT storm. He eventually passed away after the withdrawal of care, as his prognosis worsened. We recommend that a more clear guideline will help manage this devastating disease, resulting in mortality reduction.

Mitochondrial DNA deletion and duplication in Kearns-Sayre Syndrome (KSS) with initial presentation as Pearson Marrow-Pancreas Syndrome (PMPS): Two case reports in Barranquilla, Colombia

Background

Kearns–Sayre Syndrome (KSS) and Pearson Marrow‐Pancreas Syndrome (PMPS) are among the classic phenotypes caused by mitochondrial DNA (mtDNA) deletions. KSS is a rare mitochondrial disease defined by a classic triad of progressive external ophthalmoplegia, atypical pigmentary retinopathy, and onset before 20 years. PMPS presents in the first year of life with bone marrow failure and exocrine pancreatic dysfunction, and can evolve into KSS later in life. Even though an mtDNA deletion is the most frequent mutation in KSS and PMPS, cases of duplications and molecular rearrangements have also been described. In Colombia, few case reports of KSS and PMPS have been published in indexed journals or have been registered in scientific events.

Methods

We discuss clinical and genetic aspects of two case reports of pediatric female patients, with initial clinical diagnosis of PMPS who later evolved into KSS, with confirmatory molecular studies of an mtDNA deletion and an mtDNA duplication.

Results

A large‐scale mtDNA deletion, NC_012920.1:m.8286_14416del, was confirmed by Southern Blot in patient 1. An mtDNA duplication of 7.9 kb was confirmed by MLPA in patient 2.

Conclusions

Our findings are compatible with the phenotypic and genetic presentation of PMPS and KSS. We present the first molecularly confirmed case reports of Colombian patients, diagnosed initially with PMPS, who later evolved to KSS.

Mitochondrial DNA mutations and cardiovascular disease

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is responsible for more morbidity and mortality worldwide than any other ailment. Strategies for reducing CVD prevalence must involve identification of individuals at high risk for these diseases, and the prevention of its initial development. Such preventive efforts are currently limited by an incomplete understanding of the genetic determinants of CVD risk. In this review, evidence for the involvement of inherited mitochondrial mutations in development of CVD is examined.

RECENT FINDINGS

Several forms of CVD have been documented in the presence of pathogenic mitochondrial DNA (mtDNA) mutations, both in isolation and as part of larger syndromes. Other 'natural' mtDNA polymorphisms not overtly tied to any pathology have also been associated with alterations in mitochondrial function and individual risk for CVD, but until very recently these studies have been merely correlative. Fortunately, novel animal models are now allowing investigators to define a causal relationship between inherited 'natural' mtDNA polymorphisms, and cardiovascular function and pathology.

SUMMARY

Cardiovascular involvement is highly prevalent among patients with pathogenic mtDNA mutations. The relationship between CVD susceptibility and 'natural' mtDNA polymorphisms requires further investigation, but will be aided in the near future by several novel experimental models.

Kearns Sayre Syndrome: Looking beyond A-V conduction

A 15-year-old boy was diagnosed with Kayne Sayre Syndrome. He presented with pigmentary retinopathy, progressive ophthalmoplegia and complete heart block. He received a transvenous dual chamber pacemaker. Two years later he died suddenly while at home. This case highlights the importance of recognizing mechanisms other than heart block as a cause of sudden death in a patient with KSS.

Dilated cardiomyopathy with cardiogenic shock in a child with Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS) is a mitochondrial myopathy resulting from mitochondrial DNA deletion. This syndrome primarily involves the central nervous system, eyes, skeletal muscles and the heart. The most well-known cardiac complications involve the conduction system; however, there have been case reports describing cardiomyopathy. We describe a case of a child with KSS who presented with decompensated cardiac failure from dilated cardiomyopathy representing cardiomyocyte involvement of KSS. Our patient had a rapidly progressing course, despite maximal medical management, requiring emergent institution of extracorporeal membrane oxygenation and transition to a ventricular assist device. To the best of our knowledge, this is the youngest patient in the literature to have dilated cardiomyopathy in KSS.

Mitochondrial cardiomyopathy and related arrhythmias

Mitochondrial dysfunction has been shown to be involved in the pathophysiology of arrhythmia, not only in inherited cardiomyopathy due to specific mutations in the mitochondrial DNA but also in acquired cardiomyopathy such as ischemic or diabetic cardiomyopathy. This article briefly discusses the basics of mitochondrial physiology and details the mechanisms generating arrhythmias due to mitochondrial dysfunction. The clinical spectrum of inherited and acquired cardiomyopathies associated with mitochondrial dysfunction is discussed followed by general aspects of the management of mitochondrial cardiomyopathy and related arrhythmia.

Cardiac manifestations of primary mitochondrial disorders

OBJECTIVES

One of the most frequently affected organs in mitochondrial disorders (MIDs), defined as hereditary diseases due to affection of the mitochondrial energy metabolism, is the heart. Cardiac involvement (CI) in MIDs has therapeutic and prognostic implications. This review aims at summarizing and discussing the various cardiac manifestations in MIDs.

METHODS

Data for this review were identified by searches of MEDLINE, Current Contents, and PubMed using appropriate search terms.

RESULTS

CI in MIDs may be classified according to various different criteria. In the present review cardiac abnormalities in MIDs are discussed according to their frequency with which they occur. CI in MIDs includes cardiomyopathy, arrhythmias, heart failure, pulmonary hypertension, dilation of the aortic root, pericardial effusion, coronary heart disease, autonomous nervous system dysfunction, congenital heart defects, or sudden cardiac death. The most frequent among the cardiomyopathies is hypertrophic cardiomyopathy, followed by dilated cardiomyopathy, and noncompaction.

CONCLUSIONS

CI in MID is more variable and prevalent than previously thought. All tissues of the heart may be variably affected. The most frequently affected tissue is the myocardium. MIDs should be included in the differential diagnoses of cardiac disease.

Batteries not included: diagnosis and management of mitochondrial disease

In 1998, Wallace et al. (Science 1988; 242: 1427-30) published evidence that the mutation m.11778G>A was responsible for causing Leber's hereditary optic neuropathy. This was the first account of a mitochondrial DNA mutation being irrefutably linked with a human disease and was swiftly followed by a report from Holt et al. (Nature 1988; 331: 717-9) identifying deletions in mitochondrial DNA as a cause for myopathy. During the subsequent 20 years there has been an exponential growth in 'mitochondrial medicine', with clinical, biochemical and genetic characterizations of a wide range of mitochondrial diseases and evidence implicating mitochondria in a host of many other clinical conditions including ageing, neurodegenerative illness and cancer. In this review we shall focus on the diagnosis and management of mitochondrial diseases that lead directly or indirectly to disruption of the process of oxidative phosphorylation.