A high prevalence of arterial hypertension in patients with mitochondrial diseases

Diagnosis and Management of Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes Syndrome

Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a complex mitochondrial disorder characterized by a wide range of systemic manifestations. Key clinical features include recurrent stroke-like episodes, seizures, lactic acidosis, muscle weakness, exercise intolerance, sensorineural hearing loss, diabetes, and progressive neurological decline. MELAS is most commonly associated with mutations in mitochondrial DNA, particularly the m.3243A>G mutation in the MT-TL1 gene, which encodes tRNALeu (CUR). These mutations impair mitochondrial protein synthesis, leading to defective oxidative phosphorylation and energy failure at the cellular level. The clinical presentation and severity vary widely among patients, but the syndrome often results in significant morbidity and reduced life expectancy because of progressive neurological deterioration. Current management is largely focused on conservative care, including anti-seizure medications, arginine or citrulline supplementation, high-dose taurine, and dietary therapies. However, these therapies do not address the underlying genetic mutations, leaving many patients with substantial disease burden. Emerging experimental treatments, such as gene therapy and mitochondrial replacement techniques, aim to correct the underlying genetic defects and offer potential curative strategies. Further research is essential to understand the pathophysiology of MELAS, optimize current therapies, and develop novel treatments that may significantly improve patient outcomes and extend survival.

Refractory Hypotension in a Late-Onset Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS) Male with m.3243 A>G Mutation: A Case Report

(1) Introduction: Symptom spectrum can be of great diversity and heterogeneity in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) patients in clinical practice. Here, we report a case of MELAS presenting asymptomatic refractory hypotension with m.3243 A>G mutation. (2) Case representation: A 51-year-old male patient presented with a headache, vertigo, and difficulty in expression and understanding. The magnetic resonance imaging of the brain revealed an acute stroke-like lesion involving the left temporoparietal lobe. A definitive diagnosis of MELAS was given after the genetic test identified the chrM-3243 A>G mutation. The patient suffered recurrent stroke-like episodes in the 1-year follow-up. Notably, refractory hypotension was observed during hospitalizations, and no significant improvement in blood pressure was found after continuous use of vasopressor drugs and fluid infusion therapy. (3) Conclusions: We report a case of refractory hypotension which was unresponsive to fluid infusion therapy found in a patient with MELAS. Our case suggests that comprehensive management should be paid attention to during treatment. A further study on the pathological mechanism of the multisystem symptoms in MELAS would be beneficial to the treatment of patients.

Cardiac Outcomes in Adults With Mitochondrial Diseases

BACKGROUND

Patients with mitochondrial diseases are at risk of heart failure (HF) and arrhythmic major adverse cardiac events (MACE).

OBJECTIVES

We developed prediction models to estimate the risk of HF and arrhythmic MACE in this population.

METHODS

We determined the incidence and searched for predictors of HF and arrhythmic MACE using Cox regression in 600 adult patients from a multicenter registry with genetically confirmed mitochondrial diseases.

RESULTS

Over a median follow-up time of 6.67 years, 29 patients (4.9%) reached the HF endpoint, including 19 hospitalizations for nonterminal HF, 2 cardiac transplantations, and 8 deaths from HF. Thirty others (5.1%) reached the arrhythmic MACE, including 21 with third-degree or type II second-degree atrioventricular blocks, 4 with sinus node dysfunction, and 5 sudden cardiac deaths. Predictors of HF were the m.3243A>G variant (HR: 4.3; 95% CI: 1.8-10.1), conduction defects (HR: 3.0; 95% CI: 1.3-6.9), left ventricular (LV) hypertrophy (HR: 2.6; 95% CI: 1.1-5.8), LV ejection fraction <50% (HR: 10.2; 95% CI: 4.6-22.3), and premature ventricular beats (HR: 4.1; 95% CI: 1.7-9.9). Independent predictors for arrhythmia were single, large-scale mtDNA deletions (HR: 4.3; 95% CI: 1.7-10.4), conduction defects (HR: 6.8; 95% CI: 3.0-15.4), and LV ejection fraction <50% (HR: 2.7; 95% CI: 1.1-7.1). C-indexes of the Cox regression models were 0.91 (95% CI: 0.88-0.95) and 0.80 (95% CI: 0.70-0.90) for the HF and arrhythmic MACE, respectively.

CONCLUSIONS

We developed the first prediction models for HF and arrhythmic MACE in patients with mitochondrial diseases using genetic variant type and simple cardiac assessments.

Higher SBP in female patients with mitochondrial disease

BACKGROUND

Previous research suggests that hypertension is more prevalent among patients with mitochondrial diseases. Blood pressure (BP) is linearly related to increased cardiovascular risk, and this relationship is strongest for SBP; nevertheless, studies on SBP and DBP in mitochondrial diseases have not yet been performed.

METHOD

In a retrospective case-control study design, BP in mitochondrial disease patients was compared with BP in a population cohort. Secondly, using multiple linear regression, we examined blood pressure differences in various genetic mitochondrial diseases. Lastly, we explored additional predictors of BP in a subgroup with the m.3243A>G variant.

RESULTS

Two hundred and eighty-six genetically confirmed mitochondrial disease patients were included. One hundred and eighty of these patients carried the m.3243A>G mitochondrial DNA variant. SBP was 9 mmHg higher in female mitochondrial disease patients than in the general female population (95% CI: 4.4-13.3 mmHg, P < 0.001), whereas male patients had similar BP compared with controls. BP was not significantly different in patients with m.8344A>G and m.8363G>A, a mtDNA deletion or a nuclear mutation compared with m.3243A>G patients. Higher SBP was a predictor for left ventricular hypertrophy in the m.3243A>G subgroup (P = 0.04).

CONCLUSION

Novel aspects of the role of mitochondrial dysfunction in blood pressure regulation are exposed in this study. Compared with the general population, female mitochondrial disease patients have a higher SBP. Left ventricular hypertrophy is more prevalent in patients with higher SBP. Clinicians should be aware of this to prevent hypertensive complications in mitochondrial disease patients.

Prevalence of heart disease in patients with mitochondrial abnormalities on skeletal muscle biopsy

Objective

Mitochondrial DNA mutations are associated with an increased risk of heart disease. Whether an increased prevalence of cardiovascular disease is present in patients presenting with mitochondrial abnormalities on skeletal muscle biopsy remains unknown. This study was designed to determine the prevalence of cardiac conduction disease and structural heart disease in patients presenting with mitochondrial abnormalities on skeletal muscle biopsy.

Methods

This is a retrospective cohort study of 103 patients with mitochondrial abnormalities on skeletal muscle biopsy who were referred for evaluation of muscle weakness at a single tertiary care referral center from 2012 to 2018. Of these patients, 59 (57.3%) had an electrocardiogram available and were evaluated for the presence of conduction disease. An echocardiogram was available in 43 patients (42%) who were evaluated for the presence of structural heart disease. The prevalence of cardiac disease was compared to control cohort populations (Framingham and the Atherosclerosis Risk in Communities, ARIC cohorts).

Results

Mitochondrial abnormalities associated with cardiac conduction disease (defined as QRS duration ≥ 120 msec) were present in 8.9%, versus 2.0% (p < 0.001) in the Framingham population and 2.6% (p = 0.003) in the ARIC cohort. LV systolic dysfunction (LVEF ≤ 50%) was present in 11.6%, versus 3.6% (p < 0.01) in the Framingham and 3% (p < 0.01) in the ARIC populations. Left ventricular hypertrophy was present in 28.6%, versus 13.6% (p < 0.02) in the Framingham and 10.4% (p < 0.001) in the ARIC populations.

Interpretation

Given the increased prevalence of cardiovascular disease, patients with mitochondrial abnormalities on skeletal muscle biopsy should undergo routine cardiac screening with physical exam, electrocardiography, and cardiac imaging.

Atherosclerosis Can Be Mitochondrial: A Review

One of the systems that are potentially affected in mitochondrial disorders, but hardly get systematically investigated, are the arteries. One of the phenotypic manifestations in arteries is atherosclerosis. This review focuses on the current knowledge and recent advances of mitochondrial atherosclerosis. We conducted a systematic literature review via PubMed using appropriate search terms.

Atherosclerosis in mitochondrial disorders may result from a primary pathomechanism or a secondary one due to mitochondrial diabetes, arterial hypertension, or hyperlipidemia. Anecdotal reports show that primary atherosclerosis can be a phenotypic feature of mitochondrial disorders. Predominantly, patients carrying mutations in mtDNA-located genes may develop primary mitochondrial atherosclerosis. Though not systematically investigated, it is conceivable that primary mitochondrial atherosclerosis results from increased oxidative stress, mitophagy, metabolic breakdown, or lactic acidosis. Mitochondrial disorder patients with primary mitochondrial atherosclerosis should receive not only antithrombotic medication but also antioxidants and cofactors.

Atherosclerosis in mitochondrial disorders may occur even in the absence of classical atherosclerosis risk factors, suggesting that atherosclerosis can be a primary manifestation of the metabolic defect. Though primary atherosclerosis in mitochondrial disorders has not been systematically investigated, anecdotal data indicate that mitochondrial dysfunction can be a mechanism for the development of primary, mitochondrial atherosclerosis. These patients require antioxidants and cofactors in addition to antithrombotic medication.