Hibernoma: a case report of a rare cardiac tumour

Background

A cardiac hibernoma is a rare phenomenon, with just a handful of reports in the literature. They are difficult to characterize with conventional imaging including echocardiography, computed tomography (CT), cardiac magnetic resonance (CMR), or positron emission tomography (PET). Their definitive diagnosis relies primarily on histopathology via either endovascular or surgical biopsy. Previous case reports have entailed surgical excision followed by histopathology; however, surgery may be unfavourable in some patients with increased perioperative risk.

Case summary

We present the case of a 57-year-old woman who was referred to our cardiology service with an interatrial lipomatous mass found incidentally on chest CT for assessment of rib fractures. She had 6 months of unexplained syncope, which was attributed to superior vena cava (SVC) compression demonstrated by chest CT. The mass had benign characteristics on echocardiography, CT, and CMR but was glucose-avid on PET, which indicated a possible malignancy such as liposarcoma. Her comorbid and very significant airways disease precluded her from surgical excision, so instead, endovascular biopsy was performed. Histopathology showed brown fat which was negative for mouse double minute 2 amplification on fluorescence in situ hybridisation testing; hence, a diagnosis was made of hibernoma, a rare benign tumour of brown fat. Given the benign diagnosis and her surgical risk with severe chronic obstructive pulmonary disease, a multidisciplinary recommendation was made favouring conservative management, with careful ongoing follow-up and the consideration of SVC stenting if symptoms progressed.

Discussion

The definitive diagnosis of a cardiac hibernoma is complex and relies heavily on histopathology due to the contradictory findings on chest imaging. Careful consideration of management within a multidisciplinary team setting is essential to achieve a successful outcome.

Clinical outcomes of 10 years of cardiac screening in elite New Zealand athletes

OBJECTIVES

To report findings from the High Performance Sport New Zealand cardiac screening programme, including comparisons between sexes and ethnicities.

DESIGN

Retrospective cohort study.

METHODS

Elite Olympic-sport athletes were screened (2012-2022) with personal/family history, physical examination, resting 12-lead ECG and followed from the date of first screening until July 2022. An audit reviewed screening records, including demographic data, ECGs, follow-up and diagnoses. Flagged/equivocal ECGs were re-reviewed (International Criteria).

RESULTS

2075 ECGs from 1189 athletes (53 % female, mean age 21 years; 83 % European, 9 % Māori, 5 % Pacific Islander, 3 % other) were included. No athletes retired for cardiac reasons; there were no cardiac deaths or major cardiac incidents (mean follow-up from first screening: 6.1 years (range: 0.6-10.9 years)). Diagnoses included Wolff-Parkinson-White (WPW) syndrome (0.7 %) and cardiomyopathies (0.3 %). Overall, 3.5 % of ECGs were abnormal, with ECGs of females more commonly abnormal (4.4 % vs 2.5 %, p = 0.02) and with a higher proportion of ECGs with abnormal T-wave inversion (TWI) (3.1 % vs 0.9 %, p < 0.001) compared to males. Of the abnormal TWI in females (all aged ≥16 years), 47 % was limited to V1-V3 with no other abnormalities. Abnormality rates were similar between Māori, Pacific Islander and European athlete ECGs.

CONCLUSIONS

WPW was the most frequent diagnosis, with very little cardiomyopathy found. The proportion of abnormal ECGs was low overall, but higher in females. This was driven by anterior TWI in V1-V3 which was not associated with diagnoses of conditions associated with sudden cardiac death (SCD). There was no difference in the proportion of abnormal ECGs of Māori or Pacific Island athletes compared to European athletes.

Coronary microvascular dysfunction: A review of recent progress and clinical implications

The coronary microcirculation plays a cardinal role in regulating coronary blood flow to meet the changing metabolic demands of the myocardium. Coronary microvascular dysfunction (CMD) refers to structural and functional remodeling of the coronary microcirculation. CMD plays a role in the pathogenesis of obstructive and non-obstructive coronary syndromes as well as myocardial diseases, including heart failure with preserved ejection fraction (HFpEF). Despite recent diagnostic advancements, CMD is often under-appreciated in clinical practice, and may allow for the development of novel therapeutic targets. This review explores the diagnosis and pathogenic role of CMD across a range of cardiovascular diseases, its prognostic significance, and the current therapeutic landscape.

Automatic segmentation of the great arteries for computational hemodynamic assessment

BACKGROUND

Computational fluid dynamics (CFD) is increasingly used for the assessment of blood flow conditions in patients with congenital heart disease (CHD). This requires patient-specific anatomy, typically obtained from segmented 3D cardiovascular magnetic resonance (CMR) images. However, segmentation is time-consuming and requires expert input. This study aims to develop and validate a machine learning (ML) method for segmentation of the aorta and pulmonary arteries for CFD studies.

METHODS

90 CHD patients were retrospectively selected for this study. 3D CMR images were manually segmented to obtain ground-truth (GT) background, aorta and pulmonary artery labels. These were used to train and optimize a U-Net model, using a 70-10-10 train-validation-test split. Segmentation performance was primarily evaluated using Dice score. CFD simulations were set up from GT and ML segmentations using a semi-automatic meshing and simulation pipeline. Mean pressure and velocity fields across 99 planes along the vessel centrelines were extracted, and a mean average percentage error (MAPE) was calculated for each vessel pair (ML vs GT). A second observer (SO) segmented the test dataset for assessment of inter-observer variability. Friedman tests were used to compare ML vs GT, SO vs GT and ML vs SO metrics, and pressure/velocity field errors.

RESULTS

The network's Dice score (ML vs GT) was 0.945 (interquartile range: 0.929-0.955) for the aorta and 0.885 (0.851-0.899) for the pulmonary arteries. Differences with the inter-observer Dice score (SO vs GT) and ML vs SO Dice scores were not statistically significant for either aorta or pulmonary arteries (p = 0.741, p = 0.061). The ML vs GT MAPEs for pressure and velocity in the aorta were 10.1% (8.5-15.7%) and 4.1% (3.1-6.9%), respectively, and for the pulmonary arteries 14.6% (11.5-23.2%) and 6.3% (4.3-7.9%), respectively. Inter-observer (SO vs GT) and ML vs SO pressure and velocity MAPEs were of a similar magnitude to ML vs GT (p > 0.2).

CONCLUSIONS

ML can successfully segment the great vessels for CFD, with errors similar to inter-observer variability. This fast, automatic method reduces the time and effort needed for CFD analysis, making it more attractive for routine clinical use.

Analysis of athlete QT intervals by age: Fridericia and Hodges heart rate corrections outperform Bazett for athlete ECG screening

BACKGROUND

Cardiac screening of elite athletes including a 12‑lead electrocardiogram (ECG) is recommended by numerous international bodies. Current athlete ECG interpretation guidelines recommend the Bazett method to correct the QT interval (QTc).

OBJECTIVE

This study sought to investigate normative QTc changes by age using athlete screening ECGs and different QT correction methods in a population of elite cricketers.

METHODS

Initial cardiac screening ECGs from an existing database of elite Australian cricketers aged 14-35 years were examined. Average QT interval, QTcB (corrected QT-Bazett), QTcF (Fridericia), QTcH (Hodges), and heart rate (HR) were analyzed by age and sex.

RESULTS

A total of 1310 athletes (66% male, 34% female) were included with mean age 19.1 years and mean heart rate 66.9 bpm (range 38-121 bpm). With increasing age, HR decreased and absolute QT increased. The pattern of QTc change with age differed depending on the method of correction: Bazett correction (QTcB) demonstrated a "dish-shaped" or broad U-shaped appearance; while Fridericia and Hodges corrections showed a linear increase in QTc from young to older age. The Bazett method had a stronger correlation of HR with QTc (R² = 0.32) than either Fridericia (R² = 0.0007) or Hodges (R² = 0.009) methods.

CONCLUSIONS

The Bazett method is not the most accurate QT correction in athletes, especially during adolescence. In elite cricketers, QTcB revealed a drop in QTc from adolescence to early adulthood due to mis-correction of the QT interval. The Fridericia method has the smoothest correction of HR and least QT variation by age and may be preferred for athlete screening.

A Bayesian network analysis quantifying risks versus benefits of the Pfizer COVID-19 vaccine in Australia

The Pfizer COVID-19 vaccine is associated with increased myocarditis incidence. Constantly evolving evidence regarding incidence and case fatality of COVID-19 and myocarditis related to infection or vaccination, creates challenges for risk-benefit analysis of vaccination. Challenges are complicated further by emerging evidence of waning vaccine effectiveness, and variable effectiveness against variants. Here, we build on previous work on the COVID-19 Risk Calculator (CoRiCal) by integrating Australian and international data to inform a Bayesian network that calculates probabilities of outcomes for the delta variant under different scenarios of Pfizer COVID-19 vaccine coverage, age groups (≥12 years), sex, community transmission intensity and vaccine effectiveness. The model estimates that in a population where 5% were unvaccinated, 5% had one dose, 60% had two doses and 30% had three doses, there was a substantially greater probability of developing (239–5847 times) and dying (1430–384,684 times) from COVID-19-related than vaccine-associated myocarditis (depending on age and sex). For one million people with this vaccine coverage, where transmission intensity was equivalent to 10% chance of infection over 2 months, 68,813 symptomatic COVID-19 cases and 981 deaths would be prevented, with 42 and 16 expected cases of vaccine-associated myocarditis in males and females, respectively. These results justify vaccination in all age groups as vaccine-associated myocarditis is generally mild in the young, and there is unequivocal evidence for reduced mortality from COVID-19 in older individuals. The model may be updated to include emerging best evidence, data pertinent to different countries or vaccines and other outcomes such as long COVID.

'Stay home when sick' advice: implications for sport and exercise

The coronavirus pandemic has given everyone in society an education on the harms of spread of respiratory illness. Young healthy athletes are far less likely to suffer severe adverse consequences of viral illnesses than the elderly and frail, but they are not completely immune. Chronic fatigue (overtraining) is an uncommon outcome and myocarditis a rare one, but they both warrant due consideration. It is, therefore, a sensible individual strategy to 'stay home when sick' if only for these risks. Traditionally though, athletes have tended to push through (train and play when ill) because of competing concerns, such as key events/matches and 'not wanting to let teammates down'. Data from both low COVID-19 and high COVID-19 countries show that the number of cardiovascular deaths in a society correlates with the number of respiratory deaths at the same time, further linking respiratory viruses to cardiovascular deaths. We are now more aware of public health obligations to prevent the spread of respiratory illnesses, in particular to protect the more vulnerable members the community. This hopefully will correspond with a change in the culture of sport to one where it is considered 'the right thing to do', to 'stay home when sick'.

Clinical Implications of IL-32, IL-34 and IL-37 in Atherosclerosis: Speculative Role in Cardiovascular Manifestations of COVID-19

Atherosclerosis, which is a primary cause of cardiovascular disease (CVD) deaths around the world, is a chronic inflammatory disease that is characterised by the accumulation of lipid plaques in the arterial wall, triggering inflammation that is regulated by cytokines/chemokines that mediate innate and adaptive immunity. This review focuses on IL-32, -34 and -37 in the stable vs. unstable plaques from atherosclerotic patients. Dysregulation of the novel cytokines IL-32, -34 and -37 has been discovered in atherosclerotic plaques. IL-32 and -34 are pro-atherogenic and associated with an unstable plaque phenotype; whereas IL-37 is anti-atherogenic and maintains plaque stability. It is speculated that these cytokines may contribute to the explanation for the increased occurrence of atherosclerotic plaque rupture seen in patients with COVID-19 infection. Understanding the roles of these cytokines in atherogenesis may provide future therapeutic perspectives, both in the management of unstable plaque and acute coronary syndrome, and may contribute to our understanding of the COVID-19 cytokine storm.

A systematic review and meta-analysis of the prevalence of left ventricular non-compaction in adults

AIMS

To assess the reported prevalence of left ventricular non-compaction (LVNC) in different adult cohorts, taking in to consideration the role of diagnostic criteria and imaging modalities used.

METHODS AND RESULTS

A systematic review and meta-analysis of studies reporting LVNC prevalence in adults. Studies were sourced from Pre-Medline, Medline, and Embase and assessed for eligibility according to inclusion criteria. Eligible studies provided a prevalence of LVNC in adult populations (≥12 years). Studies were assessed, and data extracted by two independent reviewers. Fifty-nine eligible studies documenting LVNC in 67 unique cohorts were included. The majority of studies were assessed as moderate or high risk of bias. The pooled prevalence estimates for LVNC were consistently higher amongst cohorts diagnosed on cardiac magnetic resonance (CMR) imaging (14.79%, n = 26; I2 = 99.45%) compared with echocardiogram (1.28%, n = 36; I2 = 98.17%). This finding was unchanged when analysis was restricted to studies at low or moderate risk of bias. The prevalence of LVNC varied between disease and population representative cohorts. Athletic cohorts demonstrated high pooled prevalence estimates on echocardiogram (3.16%, n = 5; I2 = 97.37%) and CMR imaging (27.29%, n = 2).

CONCLUSION

Left ventricular non-compaction in adult populations is a poorly defined entity which likely encompasses both physiological adaptation and pathological disease. There is a higher prevalence with the introduction of newer imaging technologies, specifically CMR imaging, which identify LVNC changes more readily. The clinical significance of these findings remains unclear; however, there is significant potential for overdiagnosis, overtreatment, and unnecessary follow-up.

Post-mortem cardiac magnetic resonance parameters in normal and diseased conditions

Background

Post-mortem cardiac magnetic resonance (CMR) is a non-invasive alternative to conventional autopsy. At present, diagnostic guidelines for cardiovascular conditions such as hypertrophic cardiomyopathy have not been established. We correlated post-mortem CMR images to definite conventional autopsy findings and hypothesed that elevated T2-weighted signal intensity and RV to LV area ratios can identify myocardial infarction and pulmonary emboli respectively.

Methods

For this unblinded pilot sub-study, we selected cases from the original blinded study that compared post-mortem imaging to conventional autopsy in patients referred for coronial investigation between October 2014 to November 2016. Three groups of scans were selected based on the cause of death identified by conventional autopsy: non-cardiovascular causes of death with no structural cardiac abnormality i.e., control cases, acute/subacute myocardial infarction and pulmonary emboli. Left ventricular (LV) wall thickness, LV myocardial signal intensity and ventricular cavity areas were measured.

Results

Fifty-six scans were selected [39 (69.6%) males]: 37 (66.1%) controls, eight (14.3%) acute/subacute myocardial infarction and eleven (19.6%) pulmonary emboli. The median age was 61 years [Interquartile range (IQR) 50-73] and the median time from death to imaging and autopsy was 2 days (IQR 2-3) and 3 days (IQR 3-4). The septal and lateral walls were thicker {15 mm [13-17] and 15 mm [14-18]} on post-mortem CMR than published ante-mortem measurements. Areas of acute/subacute myocardial infarction had significantly higher T2-weighted signal intensity (normalised to skeletal muscle) compared to normal myocardium in those who died from other causes {2.5 [2.3-3.0.] vs. 1.9 [1.8-2.3]; P<0.001}. In cases with pulmonary emboli, there was definite RV enlargement with a larger indexed RV to LV area ratio compared to those who died from other causes {2.9 [2.5-3.0] vs. 1.8 [1.5-2.0]; P<0.001}.

Conclusions

We present potential post-mortem CMR parameters to identify important cardiovascular abnormalities that may be beneficial when conventional autopsy cannot be performed. In patients without cardiovascular disease, LV wall thickness was found to be unreliable in diagnosing hypertrophic cardiomyopathy without histological and/or genetic testing. Elevated T2 signal intensity and RV to LV area ratios may be useful markers for acute/subacute myocardial infarction and pulmonary emboli. Larger studies will be necessary to define cut-offs.

Comparison of conventional autopsy with post-mortem magnetic resonance, computed tomography in determining the cause of unexplained death

Conventional autopsy is the gold standard for identifying unexplained death but due to declines in referrals, there is an emerging role for post-mortem imaging. We evaluated whether post-mortem magnetic resonance (PMMR) and computed tomography (PMCT) are inferior to conventional autopsy. Deceased individuals ≥ 2 years old with unexplained death referred for coronial investigation between October 2014 to December 2016 underwent PMCT and PMMR prior to conventional autopsy. Images were reported separately and then compared to the autopsy findings by independent and blinded investigators. Outcomes included the accuracy of imaging modalities to identify an organ system cause of death and other significant abnormalities. Sixty-nine individuals underwent post-mortem scanning and autopsy (50 males; 73%) with a median age of 61 years (IQR 50-73) and median time from death to imaging of 2 days (IQR 2-3). With autopsy, 48 (70%) had an organ system cause of death and were included in assessing primary outcome while the remaining 21 (30%) were only included in assessing secondary outcome; 12 (17%) had a non-structural cause and 9 (13%) had no identifiable cause. PMMR and PMCT identified the cause of death in 58% (28/48) of cases; 50% (24/48) for PMMR and 35% (17/48) for PMCT. The sensitivity and specificity were 57% and 57% for PMMR and 38% and 73% for PMCT. Both PMMR and PMCT identified 61% (57/94) of other significant abnormalities. Post-mortem imaging is inferior to autopsy but when reported by experienced clinicians, PMMR provides important information for cardiac and neurological deaths while PMCT is beneficial for neurological, traumatic and gastrointestinal deaths.

Exercise Intolerance, Benefits, and Prescription for People Living With a Fontan Circulation: The Fontan Fitness Intervention Trial (F-FIT)-Rationale and Design

Background: Despite developments in surgical techniques and medical care, people with a Fontan circulation still experience long-term complications; non-invasive therapies to optimize the circulation have not been established. Exercise intolerance affects the majority of the population and is associated with worse prognosis. Historically, people living with a Fontan circulation were advised to avoid physical activity, but a small number of heterogenous, predominantly uncontrolled studies have shown that exercise training is safe-and for unique reasons, may even be of heightened importance in the setting of Fontan physiology. The mechanisms underlying improvements in aerobic exercise capacity and the effects of exercise training on circulatory and end-organ function remain incompletely understood. Furthermore, the optimal methods of exercise prescription are poorly characterized. This highlights the need for large, well-designed, multi-center, randomized, controlled trials. Aims and Methods: The Fontan Fitness Intervention Trial (F-FIT)-a phase III clinical trial-aims to optimize exercise prescription and delivery in people with a Fontan circulation. In this multi-center, randomized, controlled study, eligible Fontan participants will be randomized to either a 4-month supervised aerobic and resistance exercise training program of moderate-to-vigorous intensity followed by an 8-month maintenance phase; or usual care (control group). Adolescent and adult (≥16 years) Fontan participants will be randomized to either traditional face-to-face exercise training, telehealth exercise training, or usual care in a three-arm trial with an allocation of 2:2:1 (traditional:telehealth:control). Children (<16 years) will be randomized to either a physical activity and exercise program of moderate-to-vigorous intensity or usual care in a two-arm trial with a 1:1 allocation. The primary outcome is a change in aerobic exercise capacity (peak oxygen uptake) at 4-months. Secondary outcomes include safety, and changes in cardiopulmonary exercise testing measures, peripheral venous pressure, respiratory muscle and lung function, body composition, liver stiffness, neuropsychological and neurocognitive function, physical activity levels, dietary and nutritional status, vascular function, neurohormonal activation, metabolites, cardiac function, quality of life, musculoskeletal fitness, and health care utilization. Outcome measures will be assessed at baseline, 4-months, and 12-months. This manuscript will describe the pathophysiology of exercise intolerance in the Fontan circulation and the rationale and protocol for the F-FIT.

Left Ventricular Non-Compaction: Review of the Current Diagnostic Challenges and Consequences in Athletes

Left ventricular non-compaction (LVNC) is a complex clinical condition with no diagnostic gold standard. At present, there is trepidation about the accuracy of the diagnosis, the correlation to clinical outcomes and the long-term medical management. This article reviews the current imaging criteria, the limitations of echocardiography and cardiac magnetic resonance and the consequences of LV hypertrabeculation in athletes.

Genetic architecture of left ventricular noncompaction in adults

The genetic etiology and heritability of left ventricular noncompaction (LVNC) in adults is unclear. This study sought to assess the value of genetic testing in adults with LVNC. Adults diagnosed with LVNC while undergoing screening in the context of a family history of cardiomyopathy were excluded. Clinical data for 35 unrelated patients diagnosed with LVNC at ≥18 years of age were retrospectively analyzed. Left ventricular (LV) dysfunction, electrocardiogram (ECG) abnormalities, cardiac malformations or syndromic features were identified in 25 patients; 10 patients had isolated LVNC in the absence of cardiac dysfunction or syndromic features. Exome sequencing was performed, and analysis using commercial panels targeted 193 nuclear and mitochondrial genes. Nucleotide variants in coding regions or in intron-exon boundaries with predicted impacts on splicing were assessed. Fifty-four rare variants were identified in 35 nuclear genes. Across all 35 LVNC patients, the clinically meaningful genetic diagnostic yield was 9% (3/35), with heterozygous likely pathogenic or pathogenic variants identified in the NKX2-5 and TBX5 genes encoding cardiac transcription factors. No pathogenic variants were identified in patients with isolated LVNC in the absence of cardiac dysfunction or syndromic features. In conclusion, the diagnostic yield of genetic testing in adult index patients with LVNC is low. Genetic testing is most beneficial in LVNC associated with other cardiac and syndromic features, in which it can facilitate correct diagnoses, and least useful in adults with only isolated LVNC without a family history. Cardiac transcription factors are important in the development of LVNC and should be included in genetic testing panels.

Predictors of Change in Left-Ventricular Structure and Function in a Trial of Extended Hours Hemodialysis

BACKGROUND

Myocardial pathology is common in patients undergoing hemodialysis. To explore the effects of differing aspects of dialysis treatment on its evolution, we examined the impact of change in markers of volume status, hemodynamics and solute clearance on left ventricular (LV) parameters in a randomized trial of extended hours dialysis.

METHODS AND RESULTS

A Clinical Trial of IntensiVE (ACTIVE) Dialysis randomized 200 patients undergoing hemodialysis to extended dialysis hours (≥ 24 hours/week) or standard hours (12-18 hours/week) for 12 months. In a prespecified substudy, 95 participants underwent cardiac magnetic resonance imaging (CMR) at baseline and at the study's end. Generalized linear regression was used to model the relationship between changes in LV parameters and markers of volume status (normalized ultrafiltration rate and total weekly interdialytic weight gain), hemodynamic changes (systolic and diastolic blood pressure) and solute control (urea clearance, dialysis hours and phosphate). Randomization to extended hours dialysis was not associated with change in any CMR parameter. Reduction in ultrafiltration rate was associated with reduction in LV mass index (P = 0.049) and improved ejection fraction (P = 0.024); reduction in systolic blood pressure was also associated with improvement in ejection fraction (P = 0.045); reduction in interdialytic weight gain was associated with reduced stroke volume (P = 0.038). There were no associations between change in urea clearance, phosphate or total hours per week and CMR parameters.

CONCLUSIONS

Reduction in ultrafiltration rate and blood pressure are associated with improved myocardial parameters in hemodialysis recipients independently of solute clearance or dialysis time. These findings underscore the importance of fluid status and related parameters as potential treatment targets in this population.

Cardiovascular Magnetic Resonance Imaging of Inherited Heart Conditions

Imaging modalities are central to diagnosis and prognostication of confirmed or suspected inherited cardiomyopathies. The availability and use of cardiovascular magnetic resonance imaging (CMR) to supplement traditional modalities has increased substantially and has several advantages over traditional imaging techniques. CMR is unique in its ability to easily acquire images in any plane. Moreover, advances in CMR sequences have begun to enable characterisation of the myocardium without the need for invasive biopsy and has provided a major step forward in the understanding of inherited heart disease pathology and genotype-phenotype interactions. This review summarises the current role of CMR in inherited cardiomyopathies depending on their genotype and phenotype status, using arrhythmogenic right ventricular dysplasia/cardiomyopathy and hypertrophic cardiomyopathy as prototypical examples.

Long term CMR follow up of patients with right ventricular abnormality and clinically suspected arrhythmogenic right ventricular cardiomyopathy (ARVC)

BACKGROUND

The Task Force Criteria (TFC) for arrhythmogenic right ventricular cardiomyopathy (ARVC) was updated in 2010 to improve specificity. There was concern however that the revised cardiovascular magnetic resonance (CMR) criteria was too restrictive and not sensitive enough to detect early forms of the condition. We previously described patients with clinically suspected ARVC who satisfied criteria from non-imaging TFC categories and fulfilled parameters from the original but not the revised CMR criteria; as a result, these patients were not confirmed as definite ARVC but may represent an early phenotype.

METHODS

Patients scanned between 2008 and 2015 who had either right ventricular (RV) dilatation or regional dyskinesia satisfying at least minor imaging parameters from the original criteria and without contra-indication underwent serial CMR scanning using a 1.5 T scanner. The aims were to assess the risk of progressive RV abnormalities, evaluate the accuracy of the revised CMR criteria and the need for guideline directed CMR surveillance in at-risk individuals.

RESULTS

Overall, 48 patients were re-scanned; 24 had a first-degree relative diagnosed with ARVC using the revised TFC or a first-degree relative with premature sudden death from suspected ARVC and 24 patients had either left bundle branch morphology ventricular tachycardia or > 500 ventricular extra-systoles in 24-h. Mean follow up was 69+/- 25 months. The indexed RV end-diastolic, end-systolic volumes and ejection fraction were calculated for both scans. There was significant reduction in RV volumes and improvement in RV ejection fraction (EF) irrespective of changes to body surface area; - 11.7+/- 15.2 mls/m2, - 6.4+/- 10.5 mls/m2 and + 3.3 +/- 7.9% (p = 0.01, 0.01 and 0.04). Applying the RV parameters to the revised CMR criteria, two patients from the family history group (one with confirmed ARVC and one with a premature death) had progressive RV abnormalities satisfying major criteria. The remaining patients (n = 46) did not satisfy the criteria and either had normal RV parameters with regression of structural abnormalities (27,56.3%) or stable abnormalities (19,43.7%).

CONCLUSION

The revised CMR criteria represents a robust tool in the evaluation of patients with clinical suspicion of ARVC, especially for those with ventricular arrhythmias without a family history for ARVC. For patients with RV abnormalities that do not fulfill the revised criteria but have a family history of ARVC or an ARVC associated gene mutation, a surveillance CMR scan should be considered as part of the clinical follow up protocol.

A case report: X-linked dystrophin gene mutation causing severe isolated dilated cardiomyopathy

Background 

X-linked dilated cardiomyopathy (XLDCM) is a rare but rapidly progressive cardiomyopathy caused by dystrophin gene mutation. Mutations are more often associated with Duchenne and Becker Muscular Dystrophy, which are characterized by skeletal muscle weakness or limb girdle dystrophy. However, patients with isolated XLDCM have normal skeletal muscle but complete dystrophin loss in cardiac muscle resulting in isolated myocardial involvement without overt signs of skeletal myopathy.

Case summary 

A previously well 16-year-old boy developed sudden onset dense left-sided weakness and facial droop. Computed tomography (CT) angiography and CT brain showed an occluded right internal carotid artery extending to the right middle cerebral artery. He underwent successful endovascular clot retrieval but developed frank pulmonary oedema and cardiogenic shock requiring inotropic support and intubation. Transthoracic echocardiography demonstrated severe left ventricular (LV) cardiomyopathy and an apical thrombus. Subsequent cardiac magnetic resonance (CMR) imaging confirmed the LV parameters and diffuse late gadolinium enhancement. Despite absence of skeletal manifestations, subsequent genetic testing revealed an X-linked dystrophin gene mutation [c.31+G>T (IVS1G>T)]. He was commenced on empirical heart failure therapy and underwent successful cardiac transplantation.

Discussion 

X-linked dilated cardiomyopathy is a rare, rapidly progressing cardiomyopathy. Patients show normal skeletal muscle dystrophin but absent expression in cardiac muscle, resulting fibrosis, and atrophy. About 20% of affected young males have significantly reduced survival and thus the diagnosis must be considered in cases of idiopathic cardiomyopathy with CMR and genetic testing key to the diagnosis. Whilst evidence exists for empirical heart failure medications, cardiac transplantation remains the definitive treatment.

Severe right ventricular dilatation after repair of Tetralogy of Fallot is associated with increased left ventricular preload and stroke volume

Aims

Pulmonary regurgitation (PR) and right ventricular (RV) dilatation are common in repaired tetralogy of Fallot (rTOF). Left ventricular (LV) dysfunction is an important risk factor in rTOF. The effect of PR/RV dilatation on LV performance and RV-LV interactions in rTOF are incompletely understood. We examined LV responses and exercise capacity in rTOF, both before and after pulmonary valve replacement (PVR).

Methods and results

Cardiac magnetic resonance imaging scans in 126 rTOF patients (age 17.3 ± 7.6 years) were analysed, comparing subjects with indexed RV end-diastolic volume (RVEDVi) <170 mL/m2 (mild/moderate dilatation, n = 95) and RVEDVi ≥170 mL/m2 (severe dilatation, n = 31). Indexed PR volume (PRVi), RV end-systolic (RVESVi), RV end-diastolic (RVEDVi), RV stroke volume (RVSVi), net pulmonary forward flow (NPFFi), LV end-diastolic (LVEDVi), LV end-systolic (LVESVi), LV stroke volume (LVSVi), RV and LV ejection fraction (EF), and diastolic septal curvature were obtained. Peak aerobic capacity (VO2 max) was measured. In a subset (n = 30), measures were obtained pre-and-post surgical PVR. Compared to those with mild/moderate RV dilatation, patients with severe RV dilation had greater PRVi (38 ± 12 vs. 24 ± 9 mL/m2, P < 0.0001), NPFFi (53 ± 9 vs. 44 ± 11 mL/m2, P < 0.0001), LVEDVi (87 ± 14 vs. 73 ± 13 mL/m2, P < 0.0001), LVESVi (39 ± 12 vs. 30 ± 8 mL/m2, P < 0.0001), and LVSVi (48 ± 7 vs. 43  ±  8 mL/m2, P = 0.002) but lower RV ejection fraction (46 ± 8 vs. 53 ± 7%, P < 0.0001). Septal curvature and VO2 max were similar in both groups. After PVR, there was no change in LVEDVi, LVSVi, septal curvature, or VO2 max.

Conclusions

Chronic PR with severe RV dilatation is associated with increased NPFFi, LVEDVi, and LVSVi. This may potentially explain preserved exercise capacity in rTOF with severe PR and RV dilatation.

A 10-year review of sudden death during sporting activities

BACKGROUND

Sudden death during sport is a rare but devastating event. Previous research has mostly focused on sudden deaths in young competitive athletes.

OBJECTIVE

The purpose of this study was to characterize the demographics and etiologies of sudden cardiac death during sport in Australia.

METHODS

All autopsies conducted at our forensic medicine facility between 2006 and 2015 inclusive were reviewed. Sporting-related deaths among those 7-65 years of age were identified. Data collected included subject height, weight, gender, circumstances of death, and pathologic findings at autopsy.

RESULTS

A total of 19,740 autopsies were completed in the study period: 12,395 in subjects age 18-65 years (adults) and 385 in subjects age 7-17 years (children). There were 201 sports-related adult deaths at an incidence rate of 0.76-1.49 per 100,000 participant-years. Of the deaths, 74% were witnessed. Of the adult cases, 68% (n = 136) were due to cardiac causes, with coronary artery disease the most frequent cause (n = 90 [45%]). Structural abnormalities were common in adult cardiac deaths; 51 (38%) had cardiac weight ≥500 g, and 75 (55%) had left ventricular wall thickness >15 mm. Of the 15 child deaths, 5 (33%) were arrhythmogenic or presumed arrhythmic, and 5 (33%) were inherited cardiomyopathies (2 hypertrophic cardiomyopathy, 3 arrhythmogenic right ventricular cardiomyopathy).

CONCLUSION

Sudden cardiac death during sport is rare. Deaths are mostly due to coronary artery disease in adults and cardiomyopathy or arrhythmia in children. Because the majority of sports deaths are witnessed, they present an opportunity to enhance outcomes by cardiopulmonary resuscitation training and increased availability of automated external defibrillators at sports venues.

Diagnosis of Arrhythmogenic Right Ventricular Cardiomyopathy: Progress and Pitfalls

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy that predominantly affects the right ventricle. With a prevalence in the range of 1:5000 to 1:2000 persons, ARVC is one of the leading causes of sudden cardiac death in young people and in athletes. Although early detection and treatment is important, the diagnosis of ARVC remains challenging. There is no single pathognomonic diagnostic finding in ARVC; rather, current international task force criteria specify diagnostic major and minor criteria in six categories: right ventricular imaging (including echocardiography and cardiac magnetic resonance imaging (MRI)), histology, repolarisation abnormalities, depolarisation and conduction abnormalities, arrhythmias and family history (including genetic testing). Combining findings from differing diagnostic modalities can establish a "definite", "borderline" or "possible" diagnosis of ARVC. However, there are limitations inherent in the current task force criteria, including the lack of specificity for ARVC; future iterations may be improved, for example, by enhanced imaging protocols able to detect subtle changes in the structure and function of the right ventricle, incorporation of electro-anatomical data, response to adrenergic challenge, and validated criteria for interpreting genetic variants.