The impact of elite endurance activity on cardiac remodelling in asians: an echocardiographic case control study

Background

Prolonged endurance training results in physiological changes to elite athletes' hearts. These changes include thickened left ventricular (LV) walls and dilated left and right ventricles that may overlap with those from pathological conditions such as hypertrophic cardiomyopathy, dilated cardiomyopathy and arrhythmogenic cardiomyopathy. While reference ranges for elite black and white athletes have been published to facilitate differentiation of physiology from pathology, data on Asian athletes remains scarce. With increasing Asian representation in international sport, it is important to ascertain the extent of physiological cardiac remodelling in Asian athletes.

Purpose

This study aimed to compare echocardiographic parameters of elite endurance athletes (EAs) and non-endurance controls and describe reference ranges in this population of Asian athletes.

Methods

Consecutive elite athletes engaging in endurance sport were identified from the Singapore Sports Cardiology Registry from January to October 2018. Controls were obtained from 3 sources: (a) skill-based athletes from the Singapore Sports Cardiology Registry, (b) healthy non-athletic volunteers from a national atrial fibrillation registry, and (c) healthy non-athletic volunteers from a national heart failure registry. All participants underwent resting two-dimensional, M-mode and Doppler transthoracic echocardiography and findings from EA were compared with controls.

Results

165 participants (55 EAs, 110 controls) were analysed (median age 29 years, male gender n=95; 58%, Chinese ethnicity n=55 for EAs; 100%) Baseline characteristics between both groups were comparable (Table 1). EAs had larger LV wall thickness (9.2 vs. 8.1 mm, p<0.001), LV cavity size (50.7 vs. 48.2 mm, p<0.001), LV mass index (98.4 vs. 73.8 g/m2, p<0.001), aortic root diameter at sinus of Valsalva (30.6 vs. 28.9 mm, p<0.01), right ventricular dimensions and biatrial volumes compared to controls (Table 2). Similar results were noted after indexing to body surface area. These associations also persisted after adjusting for age.

Conclusion(s)

Endurance activity in elite Singaporean Chinese athletes was associated with significant structural and functional cardiac remodeling compared to controls. Reference ranges for echocardiographic parameters in this population were described, allowing for more accuracy when differentiating physiology from pathology in Asian athletes.

Funding Acknowledgement

Type of funding sources: None.

Reference ranges for functional and structural echocardiographic parameters in asian athletes: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction

Physiologic cardiac remodelling is common in elite athletes, including changes such as increased left ventricle size and left ventricular wall thickness. These changes often overlap with those from pathological cardiac conditions - for instance dilated cardiomyopathy and hypertrophic cardiomyopathy - leading to diagnostic uncertainty. The availability of reference ranges specific to elite athletes, particularly Caucasian and Black ethnicities, facilitates accurate differentiation between physiology and pathology. However, there remains a paucity of Asian data despite an increased representation in global sport.

Purpose

To perform a systematic review and meta-analysis of cardiac imaging studies in Asian elite athletes and obtain reference values for commonly utilised parameters in this population.

Methods

We searched MEDLINE via PubMed, Embase, and the Cochrane Database for relevant studies from inception till 27th July 2021. We included observational studies that reported relevant cardiac imaging parameters in Asian elite athletes. We excluded studies that did not report gender-specific cardiac imaging parameters. After study selection and data extraction, we performed random effects meta-analysis of means to obtain the weighted mean of each relevant cardiac imaging parameter stratified by gender.

Results

We included a total of eight studies with relevant echocardiographic data from East Asia, South Asia and West Asia which comprised a total of 799 male and 206 female elite athletes participating in endurance and mixed sport disciplines. We excluded data pertaining to athletes participating in skill and power disciplines in a post-hoc manner due to paucity of data and extreme data ranges. The weighted mean left ventricular mass (g) was 211.5 (95% CI 202.6 - 220.3, I2 = 85.8%) for males, and 139.3 (95% CI 132 - 146.7, I2 = 88.2%) for females. The weighted mean left ventricular mass indexed to body surface area (g/m2) was 103.1 (95% CI 99.2 - 106.9, I2 = 79.4%) for males, and 75.1 (95% CI 71.5 - 78.6, I2 = 86.1%) for females. For left ventricular end diastolic diameter (mm), the weighted mean was 54.4 (95% CI 53.1 - 55.7, I2 = 97.3%) for males, and 47.2 (95% CI 46.2 - 48.3, I2 = 89.3%) for females. Lastly, the weighted mean left ventricular wall thickness (mm) was 9.9 (95% CI 9.6 - 10.2, I2 = 91.3%) for males, and 8.7 (95% CI 8.5 - 9, I2 = 80.7%) for females.

Conclusions

This is the first meta-analysis that provides preliminary echocardiographic reference ranges for Asian elite athletes. Statistical heterogeneity, however, is high in most outcome measures. This is likely due to the presence of confounders such as study demographics. Due to a paucity of studies, further subgroup or stratified analyses could not be performed meaningfully. More large-scale observational studies are required such that more sport, gender or region-specific data could be generated.

Prevalence and diagnostic yield of investigating t wave inversion in a large unselected pre-participation cohort of young Asian males

Background/Introduction

T wave inversion (TWI) is a potentially abnormal finding on pre-participation screening electrocardiography (ECG), as it may suggest an underlying cardiomyopathy that should be risk stratified appropriately to minimise the risk of sports-related sudden cardiac death. Existing international guidelines prescribe criteria for investigating TWI in athletes. However, it is not established if these criteria can be extrapolated to screening unselected individuals. There is also evidence recommending against investigating specific patterns of anterior TWI in certain subsets of athletes due to low diagnostic yield; whether these exemptions may apply to non-athletes is uncertain. Given the importance of physical activity for primary prevention of cardiovascular disease in the general population, more evidence to guide pre-participation ECG screening of unselected individuals is needed.

Purpose

Firstly, to determine the epidemiology of abnormal TWI in a large unselected pre-participation cohort of young males of predominantly Asian ethnicity. Secondly, to determine the diagnostic yield of an echocardiography-guided approach to investigating individuals with abnormal TWI for a cardiomyopathy.

Methods

All individuals who attended a national centre for pre-enlistment cardiac screening over 39 months from 2017 were examined. Demographic data, anthropometric data and standardised physical fitness test scores were collected. Resting 12-lead ECG was performed for all individuals. Those with abnormal TWI, defined as a negatively deflected T wave of at least 0.1 mV amplitude in two contiguous leads, were referred to tertiary centres for echocardiography.

Results

69,714 consecutive males of mean age 17.9±1.1 years were screened. 562 individuals (0.8%) displayed abnormal TWI. Better aerobic fitness, but not muscular strength, was associated with a higher prevalence of abnormal TWI in general and specifically in the anterior territory, although not beyond leads V1-V2. Aerobic fitness had no association with abnormal TWI in the inferior territory or lateral territory. Of those with abnormal TWI, 12 individuals (2.1%) were newly diagnosed with a cardiomyopathy. Significant factors associated with a cardiomyopathy diagnosis were abnormal TWI in the lateral territory, abnormal TWI in the anterior territory beyond lead V2, deeper maximum TWI depth, presence of hypertension and higher body mass index. No individual presenting with TWI restricted to solely leads V1-V2 and/or two inferior leads without abnormal TWI in other contiguous leads was diagnosed with a cardiomyopathy.

Conclusion

Investigating abnormal TWI in an unselected pre-participation cohort of young Asian males had a significant yield, particularly in individuals manifesting abnormal TWI in the lateral territory and the anterior territory beyond lead V2. The ECG finding of anterior TWI in an unselected population may not be as benign as that in athletic populations.

Funding Acknowledgement

Type of funding sources: None. Abnormal TWI: Prevalence and Yield

P1925Machine learning versus classic electrocardiographic criteria for left ventricular hypertrophy in a young pre-participation cohort: results from the SAFE protocol study

Background/Introduction

Classic electrocardiographic (ECG) criteria for left ventricular hypertrophy (LVH) have been well studied in Western populations, particularly in hypertensive patients. However, their utility in Asian populations is not well studied, and their applicability to young pre-participation cohorts is unclear. We sought to evaluate the performance of classical criteria against that of machine learning models.

Aims

We sought to evaluate the performance of classical criteria against the performance of novel machine learning models in the identification of LVH.

Methodology

Between November 2009 and December 2014, pre-participation screening ECG and subsequent echocardiographic data was collected from 13,954 males aged 16 to 22, who reported for medical screening prior to military conscription.

Final diagnosis of LVH was made on echocardiography, with LVH defined as a left ventricular mass index >115g/m2. The continuous and binary forms of classical criteria were compared against machine learning models using receiver-operating characteristics (ROC) curve analysis. An 80:20 split was used to divide the data into training and test sets for the machine learning models, and three fold cross validation was used in training the models. We also compared the important variables identified by machine learning models with the input variables of classical criteria.

Results

Prevalence of echocardiographic LVH in this population was 0.91% (127 cases). Classical ECG criteria had poor performance in predicting LVH, with the best predictions achieved by the continuous Sokolow-Lyon (AUC = 0.63, 95% CI = 0.58–0.68) and the continuous Modified Cornell (AUC = 0.63, 95% CI = 0.58–0.68). Machine learning methods achieved superior performance – Random Forest (AUC = 0.74, 95% CI = 0.66–0.82), Gradient Boosting Machines (AUC = 0.70, 95% CI = 0.61–0.79), GLMNet (AUC = 0.78, 95% CI = 0.70–0.86). Novel and less recognized ECG parameters identified by the machine learning models as being predictive of LVH included mean QT interval, mean QRS interval, R in V4, and R in I.

ROC curves of models studies

Conclusion

The prevalence of LVH in our population is lower than that previously reported in other similar populations. Classical ECG criteria perform poorly in this context. Machine learning methods show superior predictive performance and demonstrate non-traditional predictors of LVH from ECG data. Further research is required to improve the predictive ability of machine learning models, and to understand the underlying pathology of the novel ECG predictors identified.

P308Utility of a prominent R wave in lead V1 of a resting electrocardiogram for detecting significant cardiac pathology in an unselected population of young males

Background

Pre-participation electrocardiogram (ECG) screening is proposed as a means to detect cardiac pathology in asymptomatic individuals, and to select individuals for further cardiac investigation. Isolated ECG finding of Right Ventricular Hypertrophy (RVH) does not require further investigation based on the recent 2017 International Criteria. However, a prominent R wave in V1 has been described in cardiac abnormalities such as Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, cardiomyopathy in Duchenne muscular dystrophy, arrhythmogenic right ventricular cardiomyopathy (ARVC), atrial septal defect and pulmonary hypertension.

Purpose

We sought to examine the utility of a prominent R wave in V1 as a screening criterion in an asymptomatic young male population of predominantly non-athletes, to detect significant structural cardiac pathology.

Methods

As part of the Singapore Armed Forces Electrocardiographic and Echocardiographic (SAFE) Protocol Study, pre-military enlistment screening ECG data was collected from 144,346 males between the ages of 16 to 22 from November 2009 to December 2014. Patients with ECGs with a prominent R wave, defined as an R wave ≥0.5mV in lead V1 with an R/S ratio of ≥1, were sent to a tertiary medical facility for a detailed transthoracic echocardiogram and subsequent cardiologist review. Any cardiac pathology identified was deemed significant if it led to the patient being excluded from participation in vigorous physical activity.

Results

1,144 patients with an isolated prominent R wave in V1 were studied. The mean age was 18.2±1.09 years and 81% were of Chinese ethnicity. None of the patients had echocardiographic evidence of RVH, 5 patients had a dilated right ventricle and 3 individuals had an elevated pulmonary artery systolic pressure. 11 patients (0.96%) had significant structural heart disease known to be associated with a prominent R wave in V1 that excluded them from participation in physical activity. These included large atrial septal defects (n=8), pulmonary stenosis (n=1), total anomalous pulmonary venous return (n=1) and hypertrophic cardiomyopathy (n=1). The test has a sensitivity of 21.6%, specificity of 93.4%, positive predictive value of 0.96% and negative predictive value of 99.8%,

Performance As Screening Criteria Number of Patients With Cardiac Pathology In Those Tested Positive Number of Patients With Cardiac Pathology In Those Tested Negative Positive Predictive Value (%) Negative Predictive Value (%) Sensitivity (%) Specificity (%) 11 40 0.96 99.8 21.6 93.4

Significant Cardiac Pathology Identified

Conclusion

A prominent R in V1 is not associated with echocardiographic RVH, or ARVC even in a large predominantly non-athletic male population. However, 0.96% of such patients would have other significant cardiac pathologies such as a large atrial septal defect.

Variations of atrioventricular block

Atrioventricular (AV) block comprises a spectrum of cardiac conduction delays with varying clinical presentations. It is commonly encountered in both hospital as well as ambulatory settings, and recognition of the type of AV conduction delay is essential for appropriate subsequent management. The electrocardiogram is a key tool for identification of patients with AV conduction delays. Contrasting management strategies should be employed for differing levels of conduction block.

CFD investigation of steady flow in bi-leaflet heart valve hinge

This paper focuses on local flow patterns inside the hinge socket of a bi-leaflet mechanical heart valve (MHV), where experimental measurements are difficult due to the extremely small flow region of about 40 microm. The overall objective of this study is to simulate the steady flow in this confined micro channel within the hinge region of a partially protruded ball hinge concept. A CFD simulation of flow through a bi-leaflet heart valve hinge was carried out. Steady flow with the valve leaflet in the fully open position during the valve systole phase was studied using FLUENT 4.4.7 running on Silicon Graphics. Body Fitted Coordinates (BFC) grid distribution was applied in the overall flow domain and great care was taken at the mesh distribution within the hinge local area. The flow study focused on local flow patterns inside the hinge socket of the valve where experimental measurements in the actual size valve are not practical. CFD results show evidence of flow in local area of hinge and no evidence of stagnation. Flow migrates across the clearance, and small vortices are formed after the hinge stoppers. The results indicate that flow in the hinge region is complex and critical for the valve to function effectively.

Computational fluid dynamics study of a protruded-hinge bileaflet mechanical heart valve

BACKGROUND AND AIM OF THE STUDY

Following clinical experience with the Medtronic Parallel bileaflet mechanical heart valve, considerable interest has been shown in investigating fluid mechanics inside the hinge socket. Most of these studies involved hinges that are recessed into the valve housing, such as the St. Jude Medical (SJM), CarboMedics, Sorin and On-X bileaflet mechanical heart valves. The aim of this study was to investigate the flow fields of a protruded hinge under steady flow conditions, with the occluder in its fully open position. Computational fluid dynamics (CFD) simulation using the Fluent 4.4.7 commercial solver was applied in this investigation. This protruded hinge mechanism for pivoting the occluder is an in-house design from the Cardiovascular Dynamics Laboratory, Nanyang Technological University.

METHODS

The Fluent 4.4.7 code was run on a Silicon Graphic Inc. computer (4-CPUx185 MHz) in the CFD simulation. A body-fitted coordinates (BFC) grid was generated to cover the entire valvular flow domain, including the interior of the hinge and leaflet. Clearance between the leaflet and pivot housing was 50-70 microm. In the vicinity of the protruded hinge, mesh cells were small compared with hinge dimensions. A power law distribution of grid points was applied to optimize the number of cells used to cluster the entire flow field. The overall computational flow domain of the valve channel, including the floating leaflet and immersed hinge, was approximately 170,000 cells in total. Inside the hinge socket, approximately 10,000 cells were generated. A comparative model with recessed hinge that resembled the SJM valve hinge design was modeled. Due to geometric difficulties, an unstructured grid scheme was applied. Great attention was focused within the hinge pocket, in particular to the clearance between the hinge pivot and leaflet. A total of 2 million cells was generated for the whole computational flow domain.

RESULTS

Under steady flow conditions, with the leaflet fixed in an open position, the protruded hinge design yielded a pair of small vortices that formed behind the stoppers. A low-magnitude velocity was observed inside the hinge clearance. Vortices developed behind the protruded stopper. Migrating flow was noted beneath the leaflet clearance as a result of pressure difference across the leaflet. For the recessed hinge design, reverse flow dominated the inside of the hinge socket, and developed into a pair of vortices at high Reynolds number.

CONCLUSION

The protruded hinge mechanism was designed to expose the overall hinge region to the mainstream flow for a positive washing effect. Flow in this protruded hinge design is, in general, found to be three-dimensional. Initial results under steady flow conditions showed low laminar and turbulent shear stress, while the hinge clearance was well washed.

Digital particle image velocimetry investigation of the pulsating flow around a simplified 2-D model of a bileaflet heart valve

BACKGROUND AND AIM OF STUDY

Strong interactions are believed to exist between the pulsating valvular flow and the valve leaflet motions. Hinge position, indicated by d/W (d = distance between the two axes of the hinge pivots; W = width of the testing section in the middle plane), plays a critical role in MHV performance. An optimized hinge position for a bileaflet heart valve can be identified as a design criterion for better valve performance.

METHODS

A two-dimensional (2-D) digital particle image velocimetry (DPIV) system was used to map the transient flow field of a simplified 2-D model of a bileaflet heart valve with a hydraulic diameter enlarged three-fold under pressure waveforms which was expanded based on Womersley number and Euler number considerations. Six different hinge positions were investigated.

RESULTS

At extreme hinge positions (d/W <0.2 or d/W >0.3), large-scale and long-duration stagnation of flow was found in the central orifice, and instability and highly disturbed flow was noted in plots of velocity vectors.

CONCLUSION

The transient flow pattern in the vicinity of the valve was greatly affected by the hinge position of moving leaflets. An optimum d/W in the range 0.2-0.3 yielded good velocity field and opening and closing behaviors.