Cardiac screening investigations in adult-onset progressive external ophthalmoplegia patients

Screening and prevalence of cardiac abnormalities on electro- and echocardiography in a large cohort of patients with mitochondrial disease

BACKGROUND

In patients with primary mitochondrial disease (MD), screening with electrocardiogram (ECG) and transthoracic echocardiography (TTE) is warranted according to current guidelines as structural cardiac abnormalities are frequent. This study aims to evaluate the cardiac phenotype of a large Dutch cohort of patients with MD and investigates whether ECG alone is sufficient for predicting structural cardiac abnormalities on TTE.

METHODS

In this retrospective cohort study, genetically confirmed MD patients >18 years old with an available ECG and TTE were included. Newcastle Mitochondrial Disease Scale for Adults (NMDAS) scores were assessed. ECG's were evaluated for rhythm and conduction disorders, voltage criteria for left ventricular hypertrophy (LVH) and repolarization disorders. Echocardiographic evaluation included left and right ventricular volumes and function, and presence of LVH or concentric remodeling.

RESULTS

In total, 200 MD patients were included with a median age of 45 years (IQR; 37-57) of whom 36% were male. Of all MD patients, 35% had abnormalities on ECG and 61% on TTE. Most frequent structural cardiac abnormalities on TTE were: global longitudinal strain > - 18% (54%), concentric remodeling (27%) and left ventricular (LV) ejection fraction <52% (14%). Patients with maternally inherited diabetes and deafness (MIDD) and mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) had the highest prevalence of ECG abnormalities (50% and 47%). TTE abnormalities were most prevalent in patients with MIDD (75%), followed by mitochondrial myopathy (MM) (55%), MELAS (47%) and Mitochondrial Epilepsy and Ragged Red Fibers (MERRF) (47%). MD patients with a high disease severity (NMDAS ≥21) had a higher prevalence of ECG abnormalities (44%, p = 0.039) and structural cardiac abnormalities (72%, p = 0.004) compared to patients with a NMDAS score of 11-20 and ≤ 10 (ECG: 34% and 19%; TTE: 63% and 39%). ECG abnormalities had a positive predictive value of 74% and a negative predictive value of 53% for structural cardiac abnormalities on TTE.

CONCLUSION

MD patients frequently have cardiac involvement especially patients with MIDD, MELAS or high NMDAS score. ECG as sole screening parameter is insufficient to detect structural cardiac abnormalities.

Risk of cardiac manifestations in adult mitochondrial disease caused by nuclear genetic defects

Objective

Regular cardiac surveillance is advocated for patients with primary mitochondrial DNA disease. However, there is limited information to guide clinical practice in mitochondrial conditions caused by nuclear DNA defects. We sought to determine the frequency and spectrum of cardiac abnormalities identified in adult mitochondrial disease originated from the nuclear genome.

Methods

Adult patients with a genetically confirmed mitochondrial disease were identified and followed up at the national clinical service for mitochondrial disease in Newcastle upon Tyne, UK (January 2009 to December 2018). Case notes, molecular genetics reports, laboratory data and cardiac investigations, including serial electrocardiograms and echocardiograms, were reviewed.

Results

In this cohort-based observational study, we included 146 adult patients (92 women) (mean age 53.6±18.7 years, 95% CI 50.6 to 56.7) with a mean follow-up duration of 7.9±5.1 years (95% CI 7.0 to 8.8). Eleven different nuclear genotypes were identified: TWNK, POLG, RRM2B, OPA1, GFER, YARS2, TYMP, ETFDH, SDHA, TRIT1 and AGK. Cardiac abnormalities were detected in 14 patients (9.6%). Seven of these patients (4.8%) had early-onset cardiac manifestations: hypertrophic cardiomyopathy required cardiac transplantation (AGK; n=2/2), left ventricular (LV) hypertrophy and bifascicular heart block (GFER; n=2/3) and mild LV dysfunction (GFER; n=1/3, YARS2; n=1/2, TWNK; n=1/41). The remaining seven patients had acquired heart disease most likely related to conventional cardiovascular risk factors and presented later in life (14.6±12.8 vs 55.1±8.9 years, p<0.0001).

Conclusions

Our findings demonstrate that the risk of cardiac involvement is genotype specific, suggesting that routine cardiac screening is not indicated for most adult patients with nuclear gene-related mitochondrial disease.

Systematic review and meta-analysis of cardiac involvement in mitochondrial myopathy

Objective

Our goal was to perform a systematic review of the literature to demonstrate the prevalence of cardiac abnormalities identified using cardiac investigations in patients with mitochondrial myopathy (MM).

Methods

This systematic review surveys the available evidence for cardiac investigations in MM from a total of 21 studies including 825 participants. Data were stratified by genetic mutation and clinical syndrome.

Results

We identified echocardiogram and ECG as the principal screening modalities that identify cardiac structural (29%) and conduction abnormalities (39%) in various MM syndromes. ECG abnormalities were more prevalent in patients with m.3243A>G mutations than other gene defects, and patients with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) had a higher prevalence of ECG abnormalities than patients with other clinical syndromes. Echocardiogram abnormalities were significantly more prevalent in patients with m.3243A>G or m.8344A>G mutations compared with other genetic mutations. Similarly, MELAS and MERRF had a higher prevalence compared with other syndromes. We observed a descriptive finding of an increased prevalence of ECG abnormalities in pediatric patients compared with adults.

Conclusions

This analysis supports the presence of a more severe cardiac phenotype in MELAS and myoclonic epilepsy with ragged red fibres syndromes and with their commonly associated genetic mutations (m.3243A>G and m.8344A>G). This provides the first evidence basis on which to provide more intensive cardiac screening for patients with certain clinical syndromes and genetic mutations. However, the data are based on a small number of studies. We recommend further studies of natural history, therapeutic response, pediatric participants, and cardiac MRI as areas for future investigation.

Chronic Progressive External Ophthalmoplegia in the Absence of Ptosis

Classically defined as bilateral, symmetric, and progressive ophthalmoparesis with myopathic ptosis, chronic progressive external ophthalmoplegia (CPEO) rarely has been reported in the absence of ptosis. We describe 2 patients with CPEO and without ptosis who presented with binocular diplopia related to small-angle esodeviations, poor fusional amplitudes, and slow saccades. In both cases, hematological studies and neuroimaging ruled out alternative etiologies, whereas muscle biopsy showed findings of mitochondrial myopathy.

Mitochondrial disease: genetics and management

Mitochondrial disease is one of the most common groups of genetic diseases with a minimum prevalence of greater than 1 in 5000 in adults. Whilst multi-system involvement is often evident, neurological manifestation is the principal presentation in most cases. The multiple clinical phenotypes and the involvement of both the mitochondrial and nuclear genome make mitochondrial disease particularly challenging for the clinician. In this review article we cover mitochondrial genetics and common neurological presentations associated with adult mitochondrial disease. In addition, specific and supportive treatments are discussed.

Characteristic cardiac phenotypes are detected by cardiovascular magnetic resonance in patients with different clinical phenotypes and genotypes of mitochondrial myopathy

BACKGROUND

Mitochondrial myopathies (MM) are a heterogeneous group of inherited conditions resulting from a primary defect in the mitochondrial respiratory chain with consecutively impaired cellular energy metabolism. Small sized studies using mainly electrocardiography (ECG) and echocardiography have revealed cardiac abnormalities ranging from conduction abnormalities and arrhythmias to hypertrophic or dilated cardiomyopathy in these patients. Recently, characteristic patterns of cardiac involvement were documented by cardiovascular magnetic resonance (CMR) in patients with chronic progressive external ophthalmoplegia (CPEO)/Kearns-Sayre syndrome (KSS) and with mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS). The present study aimed to characterize the prevalence and pattern of cardiac abnormalities and to test the additional diagnostic value of CMR in this patient population. The hypothesis that different neuromuscular MM syndromes present with different cardiac disease phenotypes was evaluated.

METHODS

Sixty-four MM patients (50 ± 15 years, 44% male) and 25 matched controls (52 ± 14 years, 36% male) prospectively underwent cardiac evaluations including CMR (comprising cine- and late-gadolinium-enhancement (LGE) imaging). Based on the neuromuscular phenotype and genotype, the patients were grouped: (a) CPEO/KSS (N = 33); (b) MELAS/-like (N = 11); c) myoclonic epilepsy with ragged-red fibers (MERRF) (N = 3) and d) other non-specific MM forms (N = 17).

RESULTS

Among the 64 MM patients, 34 (53%) had at least one abnormal CMR finding: 18 (28%) demonstrated an impaired left ventricular ejection-fraction (LV-EF <60%), 14 (22%) had unexplained LV hypertrophy and 21 (33%) were LGE-positive. Compared to controls, MM patients showed significantly higher maximal wall thickness (10 ± 3 vs. 8 ± 2 mm, p = 0.005) and concentricity (LV mass to end-diastolic volume: 0.84 ± 0.27 vs. 0.67 ± 0.11, p < 0.0001) with frequent presence of non-ischemic LGE (30% vs. 0%, p = 0.001). CPEO/KSS showed a predominantly intramural pattern of LGE mostly confined to the basal LV inferolateral wall (8/10; 80%) in addition to a tendency toward concentric remodelling. MELAS/-like patients showed the highest frequency of cardiac disease (in 10/11 (91%)), a mostly concentric LV hypertrophy (6/9; 67%) with or without LV systolic dysfunction and a predominantly focal, patchy LGE equally distributed among LV segments (8/11; 73%). Patients with MERRF and non-specific MM had no particular findings. Pathological CMR findings indicating cardiac involvement were detected significantly more often than pathological ECG results or elevated cardiac serum biomarkers (34 (53%) vs. 18 (28%) vs. 21 (33%); p = 0.008).

CONCLUSION

Cardiac involvement is a frequent finding in MM patients - and particularly present in KSS/CPEO as well as MELAS/-like patients. Despite a high variability in clinical presentation, CPEO/KSS patients typically show an intramural pattern of LGE in the basal inferolateral wall whereas MELAS patients are characterized by overt concentric hypertrophy and a rather unique, focally accentuated and diffusely distributed LGE.