Allometric scaling for left ventricular mass and geometry in male and female athletes of mixed and endurance sports

BACKGROUND

The athlete's heart (AH) defines the phenotypical changes that occur in response to chronic exercise training. Echocardiographic assessment of the AH is used to calculate LV mass (LVM) and determine chamber geometry. This is, however, interpreted using standard linear (ratiometric) scaling to body surface area (BSA) whereas allometric scaling is now widely recommended. This study (1) determined whether ratiometric scaling of LVM to BSA (LVMiratio) provides a size-independent index in young and veteran athletes of mixed and endurance sports (MES), and (2) calculated size-independent beta exponents for allometrically derived (LVMiallo) to BSA and (3) describes the physiological range of LVMiallo and the classifications of LV geometry.

METHODS

1373 MES athletes consisting of young (< 35 years old) (males n = 699 and females n = 127) and veteran (> 35 years old) (males n = 327 and females n = 220) were included in the study. LVMiratio was calculated as per standard scaling and sex-specific LVMiallo were derived from the population. Cut-offs were defined and geometry was classified according to the new exponents and relative wall thickness.

RESULTS

LVMiratio did not produce a size independent index. When tested across the age range the following indexes LVMi/BSA0.7663 and LVMi/BSA0.52, for males and females respectively, were size independent (r = 0.012; P = 0.7 and r = 0.003; P = 0.920). Physiological cut-offs for LVMiallo were 135 g/(m2)0.7663 in male athletes and 121 g/(m2)0.52 in female athletes. Concentric remodelling / hypertrophy was present in 3% and 0% of young male and female athletes and 24% and 17% of veteran male and female athletes, respectively. Eccentric hypertrophy was observed in 8% and 6% of young male and female athletes and 9% and 11% of veteran male and female athletes, respectively.

CONCLUSION

In a large cohort of young and veteran male and female MES athletes, LVMiratio to BSA is not size independent. Sex-specific LVMiallo to BSA with LVMi/BSA0.77 and LVMi/BSA0.52 for male and female athletes respectively can be applied across the age-range. Population-based cut-offs of LVMiallo provided a physiological range demonstrating a predominance for normal geometry in all athlete groups with a greater percentage of concentric remodelling/hypertrophy occurring in veteran male and female athletes.

The impact of image and performance enhancing drugs on atrial structure and function in resistance trained individuals

BACKGROUND

Image and performance enhancing drugs (IPEDs) are commonly used in resistance trained (RT) individuals and negatively impact left ventricular (LV) structure and function. Few studies have investigated the impact of IPEDs on atrial structure and function with no previous studies investigating bi-atrial strain. Additionally, the impact of current use vs. past use of IPEDs is unclear.

METHODS

Utilising a cross-sectional design, male (n = 81) and female (n = 15) RT individuals were grouped based on IPED user status: current (n = 57), past (n = 19) and non-users (n = 20). Participants completed IPED questionnaires, anthropometrical measurements, electrocardiography, and transthoracic echocardiography with strain imaging. Structural cardiac data was allometrically scaled to body surface area (BSA) according to laws of geometric similarity.

RESULTS

Body mass and BSA were greater in current users than past and non-users of IPEDs (p < 0.01). Absolute left atrial (LA) volume (60 ± 17 vs 46 ± 12, p = 0.001) and right atrial (RA) area (19 ± 4 vs 15 ± 3, p < 0.001) were greater in current users than non-users but this difference was lost following scaling (p > 0.05). Left atrial reservoir (p = 0.008, p < 0.001) and conduit (p < 0.001, p < 0.001) strain were lower in current users than past and non-users (conduit: current = 22 ± 6, past = 29 ± 9 and non-users = 31 ± 7 and reservoir: current = 33 ± 8, past = 39 ± 8, non-users = 42 ± 8). Right atrial reservoir (p = 0.015) and conduit (p = 0.007) strain were lower in current than non-users (conduit: current = 25 ± 8, non-users = 33 ± 10 and reservoir: current = 36 ± 10, non-users = 44 ± 13). Current users showed reduced LV diastolic function (A wave: p = 0.022, p = 0.049 and E/A ratio: p = 0.039, p < 0.001) and higher LA stiffness (p = 0.001, p < 0.001) than past and non-users (A wave: current = 0.54 ± 0.1, past = 0.46 ± 0.1, non-users = 0.47 ± 0.09 and E/A ratio: current = 1.5 ± 0.5, past = 1.8 ± 0.4, non-users = 1.9 ± 0.4, LA stiffness: current = 0.21 ± 0.7, past = 0.15 ± 0.04, non-users = 0.15 ± 0.07).

CONCLUSION

Resistance trained individuals using IPEDs have bi-atrial enlargement that normalises with allometric scaling, suggesting that increased size is, in part, associated with increased body size. The lower LA and RA reservoir and conduit strain and greater absolute bi-atrial structural parameters in current than non-users of IPEDs suggests pathological adaptation with IPED use, although the similarity in these parameters between past and non-users suggests reversibility of pathological changes with withdrawal.

The athlete's heart: insights from echocardiography

The manifestations of the athlete's heart can create diagnostic challenges during an echocardiographic assessment. The classifications of the morphological and functional changes induced by sport participation are often beyond 'normal limits' making it imperative to identify any overlap between pathology and normal physiology. The phenotype of the athlete's heart is not exclusive to one chamber or function. Therefore, in this narrative review, we consider the effects of sporting discipline and training volume on the holistic athlete's heart, as well as demographic factors including ethnicity, body size, sex, and age.

Insights and recommendations into service model structure, staff roles and qualifications in a UK cancer specific clinical exercise service: a multi-method qualitative study

PURPOSE

Clinical exercise delivery in the United Kingdom is disparate in terms of service structure, staff roles and qualifications, therefore it is difficult to evaluate and compare across services. Our aim was to explore, in a purposely selected cancer exercise service that was recognised as effective; (i) how staff knowledge, skills and competencies contribute to the provision of the service, (ii) how these components assist in creating effective services, and (iii) to identify existing challenges from staff and service user perspectives.

METHODS

The Consolidated Framework for Implementation Research was used as an overarching guide to review the Prehab4Cancer service. Exercise specialists and service user perspectives were explored using a multi-method approach (online semi-structured interviews, online focus group and in-person observation) and data triangulation.

RESULTS

Exercise specialists were educated to a minimum of undergraduate degree level with extensive cancer-specific knowledge and skills, equivalent to that of a Registration Council for Exercise Physiologist (RCCP) Clinical Exercise Physiologist. Workplace experience was essential for exercise specialist development in behaviour change and communications skills.

CONCLUSIONS

Staff should be educated to a level comparable with the standards for registered RCCP Clinical Exercise Physiologists, which includes workplace experience to develop knowledge, skills and competencies in real-world settings.

A New Tool to Aid the Differential Diagnosis of Physiological Remodelling from Cardiac Pathology When Assessing Left Ventricle, Left Atrial and Aortic Structure and Function in Male Arab and Black Paediatric Athletes

Aim: To determine if published Z-scores for left ventricular (LV), left atrial (LA) and aortic structure as well as indices of LV function (Doppler and TDI) in paediatric athletes and non-athletes are appropriate for application in male Arab and black paediatric athletes. If inappropriate, we aim to provide new nomograms and Z-scores for clinical application. Methods: 417 (297 Arab, 120 black) male paediatric (11-18 years) athletes, were evaluated by 2D echocardiography as per British Society of Echocardiography recommendations, and biological age (by radiological X-ray) assessment. Z-scores were tested by residual and correlation analysis together with visual inspection. New Z-scores involved allometric (a*BSA(b+c*chronological age)) and second-order polynomial (y=a*chronological age2+b*chronological age+c) equations for measures of cardiac size and indices of LV function, respectively. Results: Residual linear regression, correlation analysis and visual inspection revealed published z-scores in white peri-pubertal footballers and paediatric non-athletes to be inappropriate for application in male Arab and black paediatric athletes. Residual linear regression revealed new Z-scores for measures of LV, LA and aortic root size to be independent of BSA, ethnicity, chronological and biological age. Residual linear regression revealed new Z-scores for measures of function to be independent of chronological age. Conclusion: Our new z-scores may aid differential diagnosis of suspected pathology versus physiology remodelling, in cardiac screening of the Arab and black paediatric athlete. Nomograms are provided to assist the tracking of the paediatric athlete necessitating annual follow-up and Excel z-score calculation to facilitate use in day-to-day practice.

The effects of exercise training in the cold on cerebral blood flow and cerebrovascular function in young healthy individuals

Exercise elicits acute increases in cerebral blood flow velocity (CBFv) and provokes long-term beneficial effects on CBFv, thereby reducing cerebrovascular risk. Acute exposure to a cold stimulus also increases CBFv. We compared the impact of exercise training in cold and thermoneutral environments on CFBv, cerebrovascular function and peripheral endothelial function. Twenty-one (16 males, 22 ± 5 years) individuals were randomly allocated to either a cold (5 °C) or thermoneutral (15 °C) exercise intervention. Exercise consisted of 50-min cycling at 70% heart rate max, three times per week for eight weeks. Transcranial Doppler was used to determine pre and post intervention CBFv, dynamic cerebral autoregulation (dCA) and cerebrovascular reactivity (CVRCO2). Conduit endothelial function, microvascular function and cardiorespiratory fitness were also assessed. Cardiorespiratory fitness improved (2.91 ml.min.kg-1, 95%CI 0.49, 5.3; P = 0.02), regardless of exercise setting. Neither intervention had an impact on CBFv, CVRCO2, FMD or microvascular function (P > 0.05). There was a significant interaction between time and condition for dCA normalised gain with evidence of a decrease by 0.192%cm.s-1.%mmHg-1 (95%CI -0.318, -0.065) following training in the cold and increase (0.129%cm.s-1.%mmHg-1, 95%CI 0.011, 0.248) following training in the thermoneutral environment (P = 0.001). This was also evident for dCA phase with evidence of an increase by 0.072 rad (95%CI -0.007, 0.152) following training in the cold and decrease by 0.065 (95%CI -0.144, 0.014) radians following training in the thermoneutral environment (P = 0.02). Both training interventions improved fitness but CBFv, CVRCO2 and peripheral endothelial function were unaltered. Exercise training in the cold improved dCA whereas thermoneutral negated dCA.

Charter to establish clinical exercise physiology as a recognised allied health profession in the UK: a call to action

The UK population is growing, ageing and becoming increasingly inactive and unfit. Personalised and targeted exercise interventions are beneficial for ageing and the management of chronic and complex conditions. Increasing the uptake of effective exercise and physical activity (PA) interventions is vital to support a healthier society and decrease healthcare costs. Current strategies for exercise and PA at a population level mostly involve self-directed exercise pathways, delivered largely via the fitness industry. Even for those who opt-in and manage to achieve the current recommendations regarding minimum PA, this generic ‘one-size-fits-all’ approach often fails to demonstrate meaningful physiological and health benefits. Personalised exercise prescription and appropriate exercise testing, monitoring and progression of interventions for individuals with chronic disease should be provided by appropriately trained and recognised exercise healthcare professionals, educated in the cognate disciplines of exercise science (eg, physiology, biomechanics, motor control, psychology). This workforce has operated for >20 years in the Australian public and private healthcare systems. Accredited exercise physiologists (AEPs) are recognised allied health professionals, with demonstrable health and economic benefits. AEPs have knowledge of the risks and benefits of distinct forms of exercise, skills in the personalised prescription and optimal delivery of exercise, and competencies to support sustained PA behavioural change, based on the established scientific evidence. In this charter, we propose a road map for the training, accreditation and promotion of a clinical exercise physiology profession in the UK.

5-Year prognostic value of the right ventricular strain-area loop in patients with pulmonary hypertension

Aims

Patients with pre-capillary pulmonary hypertension (PH) show poor survival, often related to right ventricular (RV) dysfunction. In this study, we assessed the 5-year prognostic value of a novel echocardiographic measure that examines RV function through the temporal relation between RV strain (ϵ) and area (i.e. RV ϵ-area loop) for all-cause mortality in PH patients.

Methods and results

Echocardiographic assessments were performed in 143 PH patients (confirmed by right heart catheterization). Transthoracic echocardiography was utilized to assess RV ϵ-area loop. Using receiver operating characteristic curve-derived cut-off values, we stratified patients in low- vs. high-risk groups for all-cause mortality. Kaplan–Meier survival curves and uni-/multivariable cox-regression models were used to assess RV ϵ-area loop’s prognostic value (independent of established predictors: age, sex, N-terminal pro B-type natriuretic peptide, 6-min walking distance). During follow-up 45 (31%) patients died, who demonstrated lower systolic slope, peak ϵ, and late diastolic slope (all P < 0.05) at baseline. Univariate cox-regression analyses identified early systolic slope, systolic slope, peak ϵ, early diastolic uncoupling, and early/late diastolic slope to predict all-cause mortality (all P < 0.05), whilst peak ϵ possessed independent prognostic value (P < 0.05). High RV loop-score (i.e. based on number of abnormal characteristics) showed poorer survival compared to low RV loop-score (Kaplan–Meier: P < 0.01). RV loop-score improved risk stratification in high-risk patients when added to established predictors.

Conclusion

Our data demonstrate the potential for RV ϵ-area loops to independently predict all-cause mortality in patients with pre-capillary PH. The non-invasive nature and simplicity of measuring the RV ϵ-area loop, support the potential clinical relevance of (repeated) echocardiography assessment of PH patients.

Acute exercise-induced changes in cardiac function relates to right ventricular remodeling following 12-wk hypoxic exercise training

Repeated ventricular exposure to alterations in workload may relate to subsequent cardiac remodeling. We examined whether baseline acute changes in right (RV) and left ventricular (LV) function relate to chronic cardiac adaptation to 12-wk exercise training. Twenty-one healthy individuals performed 12-wk high-intensity endurance running training under hypoxia (fraction of inspired oxygen: 14.5%). Resting transthoracic echocardiography was performed before and after the training program to assess ventricular structure, function, and mechanics (including strain-area/volume loops). In addition, we examined systolic cardiac function during recumbent exercise under hypoxia at baseline (heart rate of 110-120 beats/min, "stress echocardiography"). Fifteen individuals completed training (22.0 ± 2.4 yr, 10 males). Hypoxic exercise training increased RV size, including diameter and area (all P < 0.05). With exception of an increase in RV fractional area change (P = 0.03), RV function did not change post-training (all P > 0.05). Regarding the RV strain-area loop, lower systolic and diastolic slopes were found post-training (P < 0.05). No adaptation in LV structure, function, or mechanics was observed (all P > 0.05). To answer our primary aim, we found that a greater increase in RV fractional area change during baseline stress echocardiography (r = -0.67, P = 0.01) inversely correlated with adaptation in RV basal diameter following 12-wk training. In conclusion, 12-wk high-intensity running hypoxic exercise training induced right-sided structural remodeling, which was, in part, related to baseline increase in RV fractional area change to acute exercise. These data suggest that acute cardiac responses to exercise may relate to subsequent RV remodeling after exercise training in healthy individuals.NEW & NOTEWORTHY During exercise, the right ventricle is exposed to a disproportionally higher wall stress than the left ventricle, which is further exaggerated under hypoxia. In this study, we showed that 12-wk high-intensity running hypoxic exercise training induced right-sided structural remodeling, which was, in part, related to baseline cardiac increase in RV fractional area change to acute exercise. These data suggest that acute RV responses to exercise are related to subsequent right ventricular remodeling in healthy individuals upon hypoxic training.

Exercise-induced release of troponin

It is well established that regular physical activity reduces cardiovascular disease risk; however, numerous studies have demonstrated postexercise elevations in cardiac troponin (cTn), indicative of cardiac injury in apparently healthy individuals. The prevalence of these findings in different exercise settings and population groups, as well as potential underlying mechanisms and clinical significance of exercise-induced cTn release are not yet quite determined. The present review will discuss the cTn response to exercise in light of developing cTn assays and the correlation between postexercise cTn release and cardiac function. Additionally, recent data regarding the potential link between strenuous endurance exercise and its relationship with unfavorable cardiac effects in athletes, as well as the management of patients presenting at emergency care after sport events will be briefly reviewed.

Acute impact of changes to hemodynamic load on the left ventricular strain-volume relationship in young and older men

Chronic changes in left ventricular (LV) hemodynamics, such as those induced by increased afterload (i.e., hypertension), mediate changes in LV function. This study examined the proof of concept that 1) the LV longitudinal strain (ε)-volume loop is sensitive to detecting an acute increase in afterload, and 2) these effects differ between healthy young versus older men. Thirty-five healthy male volunteers were recruited, including 19 young (24 ± 2 yr) and 16 older participants (67 ± 5 yr). Tests were performed before, during, and after 10-min recovery from acute manipulation of afterload. Real-time hemodynamic data were obtained and LV longitudinal ε-volume loops were calculated from four-chamber images using two-dimensional echocardiography. Inflation of the anti-gravity (anti-G) suit resulted in an immediate increase in heart rate, blood pressure, and systemic vascular resistance and a decrease in stroke volume (all P < 0.05). This was accompanied by a decrease in LV peak ε, slower slope of the ε-volume relationship during early diastole, and an increase in uncoupling (i.e., compared with systole; little change in ε per volume decline during early diastole and large changes in ε per volume decline during late diastole) (all P < 0.05). All values returned to baseline levels after recovery (all P > 0.05). Manipulation of cardiac hemodynamics caused comparable effects in young versus older men (all P > 0.05). Acute increases in afterload immediately change the diastolic phase of the LV longitudinal ε-volume loop in young and older men. This supports the potency of the LV longitudinal ε-volume loop to provide novel insights into dynamic cardiac function in humans in vivo.

P784 Cardiac remodelling in elite rowers - insights from novel echocardiographic techniques

Funding Acknowledgements

No financial support

Background

Chronic exercise training leads to cardiac remodelling; the so-called Athlete’s Heart. Previous studies are often limited by a cross-sectional design whilst longitudinal training studies are often constrained to the assessment of non-athletes. Echocardiography provides comprehensive assessment of mechanics and may give additional insight into short-term changes in training volume in the elite athlete.

Purpose

To examine the impact of a short-term (9 months) increase in training volume on cardiac structure and mechanics in elite international competing rowers.

Methods

As part of the work-up to the 2012 Olympic Games, twenty-seven elite rowers (26.4 ± 3.7 years, 19 male) underwent baseline echocardiography prior to and post (9-months) a planned increase in training volume. Conventional echocardiographic indices including mechanics of all cardiac chambers were assessed.

Results

In response to increased training volume, there was a significant increase in left ventricular (LV) size (IVSd 9.2 ± 1.2 to 9.7 ± 1.1 mm, p = 0.001; PWd 8.3 ± 1.3 to 8.7 ± 1.4 mm, p = 0.013), LVIDd (56.5 ± 4.6 to 57.9 ± 4.2 mm, p = 0.001), and LVMi (90.2 ± 17.8 to 100.8 ± 17.1 g/m2, p = 0.000), see table. There was a significant increase in LV twist (9.2 ± 4.5 to 11.2 ± 4.7 °, p = 0.04; basal rotation -4.4 ± 3.1 to -4.5 ± 3.4 °, p = 0.84; apical rotation 5.8 ± 3.4 to 7.1 ± 3.7 °, p = 0.011), see figure, however, there were no changes in any other conventional indices of function or any other cardiac mechanics. There was a significant increase in left atrial (LA) volume (58.8 ± 15.2 to 65.3 ± 17.6 mm, p = 0.01) whilst no changes were observed in right heart structure.

Conclusion

An increase in exercise training volume in elite rowers across 9-months induced mild balanced structural remodelling of the LV and LA with a concomitant increase in LV twist. Contradictory to findings in non-athletes, there was no increase in right ventricular or atrial structure or function which may be representative of the elite athlete status and possibly already at threshold for physiological adaptation.

Abstract P784 Figure.

Exercise-induced Changes in Soluble ST2 Concentrations in Marathon Runners

Purpose

Previous studies have suggested that extreme endurance exercise may induce cardiac microdamage that could lead to subsequent myocardial fibrosis. Soluble suppression of tumorigenicity 2 (sST2) is a cardiac biomarker for assessment of myocardial fibrosis, inflammation, and strain. We evaluated baseline and exercise-induced sST2 concentrations in a heterogeneous cohort of marathon runners to identify predictors for sST2 concentrations.

Methods

Ninety-two runners supplied demographic data, health status, physical activity levels, and marathon experience. Before (baseline) and immediately after (finish) the marathon, blood was collected for analysis of sST2 and cardiac troponin I (cTnI).

Results

Eighty-two participants (45 ± 8 yr, 79% male) finished the race in 227 ± 28 min at 92% (88%–94%) of their predicted maximum heart rate (exercise intensity). sST2 concentrations increased in all runners, from 34 (25–46) ng·mL⁻¹ to 70 (53–87) ng·mL⁻¹ (P < 0.001), and cTnI increased from 9 (5–21) ng·L⁻¹ to 60 (34–102) ng·L⁻¹ (P < 0.001). sST2 concentrations were higher in the fastest marathon runners. Sex and marathon personal best time were associated with baseline sST2 (R² = 0.27); baseline sST2, weight loss, and exercise intensity during marathon were associated with finish sST2 (R² = 0.54); baseline sST2, height, sex, and weekly training hours were associated with the exercise-induced increase in sST2 (R² = 0.47). We observed no association between sST2 and cTnI concentrations.

Conclusion

An exercise-induced increase in sST2 was observed in all marathon runners with sST2 concentrations exceeding cutoff values both at baseline (48%) and finish (94%). Faster runners had higher sST2 concentrations. Our data suggest complex variables determine sST2 concentrations in marathon runners.

P1513Exercise-induced cardiac troponin I release and incident cardiovascular morbidity and mortality

Background

Blood concentrations of cardiac troponin I (cTnI) above the 99th percentile (upper reference limit, URL) are a key criterion for the diagnosis of acute myocardial injury and infarction. cTnI concentrations, even below the URL, also predict adverse outcomes in general and patient populations. cTnI increases after exercise, but the clinical significance of this exercise-induced cTnI increase is unknown. We examined the association between exercise-induced cTnI elevations and clinical outcomes in long-distance walkers.

Methods

cTnI was measured in 726 participants (median 61 [54–69] yrs) before and immediately after 30–55 km of walking. The primary endpoint was a composite of all-cause mortality and major adverse cardiovascular events (MACE, i.e. myocardial infarction, stroke, heart failure, revascularization or sudden cardiac arrest).

Results

Participants walked 498 [440–555] min at 68±10% of their maximum heart rate. Baseline cTnI concentrations were 2 [0–8] ng/L, with 9 participants (1%) demonstrating a baseline cTnI value above the URL (>40 ng/L). cTnI increased after walking (8 [1–18] ng/L, p<0.001) and 63 participants (9%) had a post-exercise cTnI value >URL. During 43 [23–77] months of follow-up, 62 participants (9%) experienced a primary endpoint; 29 died and 33 had MACE. 27% of participants with post-exercise cTnI >URL experienced a primary endpoint compared to only 7% with cTnI below the URL (log-rank p<0.001). The hazard ratio was 2.35 (95% CI: 1.21–4.53) after adjusting for age, sex, cardiovascular risk factors (hypertension, hypercholesterolemia or diabetes mellitus), cardiovascular diseases (myocardial infarction, stroke or heart failure) and baseline cTnI.

Kaplan-Meier of Mortality and MACE

Conclusion

Post-exercise cTnI concentrations >URL were associated with higher all-cause mortality and MACE, independent of age, sex, presence of cardiovascular risk factors or cardiovascular diseases and baseline cTnI concentrations in a large cohort of older long-distance walkers. Exercise-induced increases in cTnI may not be a benign physiological response to exercise in all, but an early marker of future mortality and cardiovascular events.

Acknowledgement/Funding

V.L.A was supported by a grant from the Radboud Institute for Health Sciences, T.M.H.E by a Horizon 2020 grant from the European Commission

Exercise-Induced Cardiac Troponin I Increase and Incident Mortality and Cardiovascular Events

BACKGROUND

Blood concentrations of cardiac troponin above the 99^th percentile are a key criterion for the diagnosis of acute myocardial injury and infarction. Troponin concentrations, even below the 99^th percentile, predict adverse outcomes in patients and the general population. Elevated troponin concentrations are commonly observed after endurance exercise, but the clinical significance of this increase is unknown. We examined the association between postexercise troponin I concentrations and clinical outcomes in long-distance walkers.

METHODS

We measured cardiac troponin I concentrations in 725 participants (61 [54-69] yrs) before and immediately after 30 to 55 km of walking. We tested for an association between postexercise troponin I concentrations above the 99^th percentile (>0.040 µg/L) and a composite end point of all-cause mortality and major adverse cardiovascular events (myocardial infarction, stroke, heart failure, revascularization, or sudden cardiac arrest). Continuous variables were reported as mean ± standard deviation when normally distributed or median [interquartile range] when not normally distributed.

RESULTS

Participants walked 8.3 [7.3-9.3] hours at 68±10% of their maximum heart rate. Baseline troponin I concentrations were >0.040 µg/L in 9 participants (1%). Troponin I concentrations increased after walking (P<.001), with 63 participants (9%) demonstrating a postexercise troponin concentration >0.040 µg/L. During 43 [23-77] months of follow-up, 62 participants (9%) experienced an end point; 29 died and 33 had major adverse cardiovascular events. Compared with 7% with postexercise troponin I ≤0.040 µg/L (log-rank P<.001), 27% of participants with postexercise troponin I concentrations >0.040 µg/L experienced an end point. The hazard ratio was 2.48 (95% CI, 1.29-4.78) after adjusting for age, sex, cardiovascular risk factors (hypertension, hypercholesterolemia or diabetes mellitus), cardiovascular diseases (myocardial infarction, stroke, or heart failure), and baseline troponin I concentrations.

CONCLUSIONS

Exercise-induced troponin I elevations above the 99^th percentile after 30 to 55 km of walking independently predicted higher mortality and cardiovascular events in a cohort of older long-distance walkers. Exercise-induced increases in troponin may not be a benign physiological response to exercise, but an early marker of future mortality and cardiovascular events.

Changes in dynamic left ventricular function, assessed by the strain-volume loop, relate to reverse remodeling after aortic valve replacement

Aortic valve replacement (AVR) leads to remodeling of the left ventricle (LV). Adopting a novel technique to examine dynamic LV function, our study explored whether post-AVR changes in dynamic LV function and/or changes in aortic valve characteristics are associated with LV mass regression during follow-up. We retrospectively analyzed 30 participants with severe aortic stenosis who underwent standard transthoracic echocardiographic assessment before AVR [88 (IQR or interquartile range: 22–143) days], post-AVR [13 (6–22) days], and during follow-up [455 (226–907) days]. We assessed standard measures of LV structure, function, and aortic valve characteristics. Novel insight into dynamic LV function was provided through a four-chamber image by examination of the temporal relation between LV longitudinal strain (ε) and volume (ε-volume loops), representing the contribution of LV mechanics to volume change. AVR resulted in immediate changes in structural valve characteristics, alongside a reduced LV longitudinal peak ε and improved coherence between the diastolic and systolic part of the ε-volume loop (all P < 0.05). Follow-up revealed a decrease in LV mass ( P < 0.05) and improvements in LV ejection fraction and LV longitudinal peak ε ( P < 0.05). A significant relationship was present between decline in LV mass during follow-up and post-AVR improvement in coherence of the ε-volume loops ( r = 0.439, P = 0.03), but not with post-AVR changes in aortic valve characteristics or LV function (all P > 0.05). We found that post-AVR improvements in dynamic LV function are related to long-term remodeling of the LV. This highlights the potential importance of assessing dynamic LV function for cardiac adaptations in vivo.

NEW & NOTEWORTHY Combining temporal measures of left ventricular longitudinal strain and volume (strain-volume loop) provides novel insights in dynamic cardiac function. In patients with aortic stenosis who underwent aortic valve replacement, postsurgical changes in the strain-volume loop are associated with regression of left ventricular mass during follow-up. This provides novel insight into the relation between postsurgery changes in cardiac hemodynamics and long-term structural remodeling, but also supports the potential utility of the assessment of dynamic cardiac function.

Scaling of cardiac morphology is interrupted by birth in the developing sheep Ovis aries

Scaling of the heart across development can reveal the degree to which variation in cardiac morphology depends on body mass. In this study, we assessed the scaling of heart mass, left and right ventricular masses, and ventricular mass ratio, as a function of eviscerated body mass across fetal and postnatal development in Horro sheep Ovis aries (~50-fold body mass range; N = 21). Whole hearts were extracted from carcasses, cleaned, dissected into chambers and weighed. We found a biphasic relationship when heart mass was scaled against body mass, with a conspicuous 'breakpoint' around the time of birth, manifest not by a change in the scaling exponent (slope), but rather a jump in the elevation. Fetal heart mass (g) increased with eviscerated body mass (M_b , kg) according to the power equation 4.90 M_b ^{0.88 ± 0.26 (± 95% CI )} , whereas postnatal heart mass increased according to 10.0 M_b ^{0.88 ± 0.10} . While the fetal and postnatal scaling exponents are identical (0.88) and reveal a clear dependence of heart mass on body mass, only the postnatal exponent is significantly less than 1.0, indicating the postnatal heart becomes a smaller component of body mass as the body grows, which is a pattern found frequently with postnatal cardiac development among mammals. The rapid doubling in heart mass around the time of birth is independent of any increase in body mass and is consistent with the normalization of wall stress in response to abrupt changes in volume loading and pressure loading at parturition. We discuss variation in scaling patterns of heart mass across development among mammals, and suggest that the variation results from a complex interplay between hard-wired genetics and epigenetic influences.

Impact of 24 weeks of supervised endurance versus resistance exercise training on left ventricular mechanics in healthy untrained humans

In addition to the well-known cardiac structural adaptation to exercise training, little work has examined changes in left ventricle (LV) mechanics. With new regional and global indexes available we sought to determine the effect of 24-wk endurance versus resistance training on LV mechanics. Twenty-three male subjects were randomly allocated to a 24-wk endurance or resistance training program. Pre- and posttraining two-dimensional echocardiographic images were acquired. Global LV mechanics [strain (ε)] were recorded in longitudinal, circumferential, and radial planes. Rotation was assessed at apical and basal levels. In addition, longitudinal ε-volume loops, across the cardiac cycle, were constructed from simultaneous LV ε (longitudinal and transverse strain) and volume measurements across the cardiac cycle as a novel measure of LV mechanics. Marginal differences in ε and rotation data were found between groups. After training, we found no change in global peak ε data. Peak basal rotation significantly increased after training, with changes in the endurance group (−2.2 ± 1.9° to −4.5 ± 3.3°) and the resistance group (−2.9 ± 3.0° to −3.4 ± 2.9°). LV ε-volume loops revealed a modest rightward shift in both groups. Although most global and regional indexes of LV mechanics were not significantly altered, 24 wk of intense supervised exercise training increased basal rotation. Further studies that assess LV mechanics in larger cohorts of subjects and those with cardiovascular disease and risk factors may reveal important training impacts.

NEW & NOTEWORTHY This study builds on previous work by our group and presents a comprehensive assessment of cardiac mechanics after dichotomous exercise training programs. We highlight novel findings in addition to the inclusion of strain-volume loops, which shed light on subtle differences in longitudinal and transverse contribution to volume change throughout the cardiac cycle. Our findings suggest that training has an impact on basal rotation and possibly strain-volume loops.

Scaling to produce size-independent indices of echocardiographic derived aortic root dimensions in elite Rugby Football League players

The assessment of aortic root dimensions is important in cardiac pre-participation screening. Scaling of cardiac dimensions removes the impact of body size allowing meaningful inter/intra group comparisons. Developing appropriate scaling approaches, scaling variables and extending the application to major vessels is warranted so underlying pathology can be detected and managed appropriately. The study aims to define relationships between aortic root dimensions and body surface area/height. Two hundred and twenty elite Rugby Football League athletes were recruited. All participants completed anthropometric assessments, a 12-lead ECG and echocardiogram. Aortic root was measured at the aortic annulus, sinus of valsalva, sinotubular junction and the proximal ascending aorta. Linear and allometric scaling were performed on the relationship between aortic measurements and body surface area/height. Absolute aortic root measurements fell within normal population data (mean ± standard deviation (range): aortic annulus: 22 ± 2 (17-28) mm, sinus of valsalva: 28 ± 3 (20-38) mm, sinotubular junction: 22 ± 3 (14-33) mm, proximal ascending aorta: 22 ± 3 (15-31) mm). Linear scaling to height produced size-independent indices at all aortic measurement sites (P < 0.05). Conversely, linear scaling using body surface area did not produce size-independent indices at any site (P > 0.05). Allometric scaling, using both body surface area and height, produced size-independent indices at all sites (P < 0.05). We recommend linearly scaling aortic root dimensions to height in elite Rugby Football League athletes and discourage the use of body surface area as a linear scaling quantity. Allometric scaling is also effective when using both body surface area and height.

Prevalence and significance of T-wave inversion in Arab and Black paediatric athletes: Should anterior T-wave inversion interpretation be governed by biological or chronological age?

BACKGROUND

International electrocardiographic (ECG) recommendations regard anterior T-wave inversion (ATWI) in athletes under 16 years to be normal.

DESIGN

The aim of this study was to identify the prevalence, distribution and determinants of TWI by ethnicity, chronological and biological age within paediatric athletes. A second aim was to establish the diagnostic accuracy of international ECG recommendations against refinement within athletes who present with ECG variants isolated to ATWI (V₁-V₄) using receiver operator curve analysis. Clinical context was calculated using Bayesian analysis.

METHODS

Four hundred and eighteen Arab and 314 black male athletes (11-18 years) were evaluated by ECG, echocardiogram and biological age (by radiological X-ray) assessment.

RESULTS

A total of 116 (15.8%) athletes presented with ATWI (V₁-V₄), of which 96 (82.8%) were observed in the absence of other ECG findings considered to be abnormal as per international recommendations for ECG interpretation in athletes; 91 (12.4%) athletes presented with ATWI confined to V₁-V₃, with prevalence predicted by black ethnicity (odds ratio (OR) 2.2, 95% confidence interval (CI) 1.3-3.5) and biological age under 16 years (OR 2.0, 95% CI 1.2-3.3). Of the 96 with ATWI (V₁-V₄) observed in the absence of other ECG findings considered to be abnormal, as per international recommendations for ECG interpretation in athletes, diagnostic accuracy was 'fail' (OR 0.47, 95% CI 0.00-1.00) for international recommendations and 'excellent' (OR 0.97, 95% CI 0.92-1.00) when governed by biological age under 16 years, providing a positive and negative likelihood ratio of 15.8 (95% CI 1.8-28.1) and 0.0 (95% CI 0.0-0.8), respectively.

CONCLUSION

Interpretation of ECG variants isolated with ATWI (V₁-V₄) using international recommendations (chronological age <16 years) warrants caution, but governance by biological age yielded an 'excellent' diagnostic accuracy. In the clinical context, the 'chance' of detecting cardiac pathology within a paediatric male athlete presenting with ATWI in the absence of other ECG findings considered to be abnormal, as per international recommendations for ECG interpretation in athletes (positive likelihood ratio 15.8), was 14.4%, whereas a negative ECG (negative likelihood ratio 0.0) was 0%.

Diagnostic accuracy and Bayesian analysis of new international ECG recommendations in paediatric athletes

OBJECTIVE

Historically, electrocardiographic (ECG) interpretation criteria for athletes were only applicable to adults. New international recommendations now account for athletes ≤16 years, but their clinical appropriateness is unknown. We sought to establish the diagnostic accuracy of new international ECG recommendations against the Seattle criteria and 2010 European Society of Cardiology (ESC) recommendations in paediatric athletes using receiver operator curve analysis. Clinical context was calculated using Bayesian analysis.

METHODS

876 Arab and 428 black male paediatric athletes (11-18 years) were evaluated by medical questionnaire, physical examination, ECG and echocardiographic assessment. ECGs were retrospectively analysed according to the three criteria.

RESULTS

Thirteen (1.0%) athletes were diagnosed with cardiac pathology that may predispose to sudden cardiac arrest/death (SCA/D) (8 (0.9%) Arab and (5 (1.2%) black)). Diagnostic accuracy was poor (0.68, 95% CI 0.54 to 0.82) for 2010 ESC recommendations, fair (0.70, 95% CI 0.54 to 0.85) for Seattle criteria and fair (0.77, 95% CI 0.61 to 0.93) for international recommendations. False-positive rates were 41.0% for 2010 ESC recommendations, 21.8% for Seattle criteria and 6.8% for international recommendations. International recommendations provided a positive (+LR) and negative (-LR) post-test likelihood ratio of 9.0 (95% CI 5.1 to 13.1) and 0.4 (95% CI 0.2 to 0.7), respectively.

CONCLUSION

In Arab and black male paediatric athletes, new international recommendations outperform both the Seattle criteria and 2010 ESC recommendations, reducing false positive rates, while yielding a 'fair' diagnostic accuracy for cardiac pathology that may predispose to SCA/D. In clinical context, the 'chance' of detecting cardiac pathology within a paediatric male athlete with a positive ECG (+LR=9.0) was 8.3%, whereas a negative ECG (-LR=0.4) was 0.4%.

Left ventricular function and mechanics following prolonged endurance exercise: an update and meta-analysis with insights from novel techniques

Background

The cardiac consequences of undertaking endurance exercise are the topic of recent debate. The purpose of this review is to provide an update on a growing body of literature, focusing on left ventricular (LV) function following prolonged endurance exercise over 2 h in duration which have employed novel techniques, including myocardial speckle tracking, to provide a more comprehensive global and regional assessment of LV mechanics.

Methods

Prospective studies were filtered independently following a pre-set criteria, resulting in the inclusion of 27 studies in the analyses. A random-effects meta-analysis was used to determine the weighted mean difference and 95% confidence intervals (CI) of LV functional and mechanical data from pre-to-post-exercise. Narrative commentary was also provided where volume of available evidence precluded meta-analysis.

Results

A significant overall reduction in LV longitudinal strain (Ɛ) n = 22 (− 18 ± 1 to − 17 ± 1%; effect size (d) − 9: − 1 to − 0.5%), strain rate n = 10 (SR;d − 0.9: − 0.1.3 to − 0.5 l/s) and twistn = 5 (11.9 ± 2.2 to 8.7 ± 2.2°,d − 1: − 1.6 to − 0.3°) was observed following strenuous endurance exercise (range 120–1740 min) (P < 0.01). A smaller number of studies (n = 4) also reported a non-significant reduction in global circumferential and radial Ɛ (P > 0.05).

Conclusion

The meta-analysis and narrative commentary demonstrated that a reduction in LV function and mechanics is evident following prolonged endurance exercise. The mechanism(s) responsible for these changes are complex and likely multi-factorial in nature and may be linked to right and left ventricular interaction.

Global and regional cardiac function in lifelong endurance athletes with and without myocardial fibrosis

The aim of the present study was to compare cardiac structure as well as global and regional cardiac function in athletes with and without myocardial fibrosis (MF). Cardiac magnetic resonance imaging with late gadolinium enhancement was used to detect MF and global cardiac structure in nine lifelong veteran endurance athletes (58 ± 5 years, 43 ± 5 years of training). Transthoracic echocardiography using tissue-Doppler and myocardial strain imaging assessed global and regional (18 segments) longitudinal left ventricular function. MF was present in four athletes (range 1-8 g) and not present in five athletes. MF was located near the insertion points of the right ventricular free wall on the left ventricle in three athletes and in the epicardial lateral wall in one athlete. Athletes with MF demonstrated a larger end diastolic volume (205 ± 24 vs 173 ± 18 ml) and posterior wall thickness (11 ± 1 vs 9 ± 1 mm) compared to those without MF. The presence of MF did not mediate global tissue velocities or global longitudinal strain and strain rate; however, regional analysis of longitudinal strain demonstrated reduced function in some fibrotic regions. Furthermore, base to apex gradient was affected in three out of four athletes with MF. Lifelong veteran endurance athletes with MF demonstrate larger cardiac dimensions and normal global cardiac function. Fibrotic areas may demonstrate some co-localised regional cardiac dysfunction, evidenced by an affected cardiac strain and base to apex gradient. These data emphasize the heterogeneous phenotype of MF in athletes.

Electrical and structural adaptations of the paediatric athlete’s heart: a systematic review with meta-analysis

Aim

To describe the electrocardiographic (ECG) and echocardiographic manifestations of the paediatric athlete’s heart, and examine the impact of age, race and sex on cardiac remodelling responses to competitive sport.

Design

Systematic review with meta-analysis.

Data sources

Six electronic databases were searched to May 2016: MEDLINE, PubMed, EMBASE, Web of Science, CINAHL and SPORTDiscus.

Inclusion criteria

(1) Male and/or female competitive athletes, (2) participants aged 6–18 years, (3) original research article published in English language.

Results

Data from 14 278 athletes and 1668 non-athletes were included for qualitative (43 articles) and quantitative synthesis (40 articles). Paediatric athletes demonstrated a greater prevalence of training-related and training-unrelated ECG changes than non-athletes. Athletes ≥14 years were 15.8 times more likely to have inferolateral T-wave inversion than athletes <14 years. Paediatric black athletes had significantly more training-related and training-unrelated ECG changes than Caucasian athletes. Age was a positive predictor of left ventricular (LV) internal diameter during diastole, interventricular septum thickness during diastole, relative wall thickness and LV mass. When age was accounted for, these parameters remained significantly larger in athletes than non-athletes. Paediatric black athletes presented larger posterior wall thickness during diastole (PWTd) than Caucasian athletes. Paediatric male athletes also presented larger PWTd than females.

Conclusions

The paediatric athlete’s heart undergoes significant remodelling both before and during ‘maturational years’. Paediatric athletes have a greater prevalence of training related and training-unrelated ECG changes than non-athletes, with age, race and sex mediating factors on cardiac electrical and LV structural remodelling.

Exploratory assessment of left ventricular strain-volume loops in severe aortic valve diseases

KEY POINTS

Severe aortic valve diseases are common cardiac abnormalities that are associated with poor long-term survival. Before any reduction in left ventricular (LV) function, the left ventricle undergoes structural remodelling under the influence of changing haemodynamic conditions. In this study, we combined temporal changes in LV structure (volume) with alterations in LV functional characteristics (strain, ԑ) into a ԑ-volume loop, in order to provide novel insight into the haemodynamic cardiac consequences of aortic valve diseases in those with preserved LV ejection fraction. We showed that our novel ԑ-volume loop and the specific loop characteristics provide additional insight into the functional and mechanical haemodynamic consequences of severe aortic valve diseases (with preserved LV ejection fraction). Finally, we showed that the ԑ-volume loop characteristics provide discriminative capacity compared with conventional measures of LV function.

ABSTRACT

The purpose of this study was to examine left ventricular (LV) strain (ԑ)-volume loops to provide novel insight into the haemodynamic cardiac consequences of aortic valve stenosis (AS) and aortic valve regurgitation (AR). Twenty-seven participants were retrospectively recruited: AR (n = 7), AS (n = 10) and control subjects (n = 10). Standard transthoracic echocardiography was used to obtain apical four-chamber images to construct ԑ-volume relationships, which were assessed using the following parameters: early systolic ԑ (ԑ_ES); slope of ԑ-volume relationship during systole (Sslope); end-systolic peak ԑ (peak ԑ); and diastolic uncoupling (systolic ԑ-diastolic ԑ at same volume) during early diastole (UNCOUP_ED) and late diastole (UNCOUP_LD). Receiver operating characteristic curves were used to determine the ability to detect impaired LV function. Although LV ejection fraction was comparable between groups, longitudinal peak ԑ was reduced compared with control subjects. In contrast, ԑ_ES and Sslope were lower in both pathologies compared with control subejcts (P < 0.01), but also different between AS and AR (P < 0.05). UNCOUP_ED and UNCOUP_LD were significantly higher in both patient groups compared with control subjects (P < 0.05). Receiver operating characteristic curves revealed that loop characteristics (AUC = 0.99, 1.00 and 1.00; all P < 0.01) were better able then peak ԑ (AUC = 0.75, 0.89 and 0.76; P = 0.06, <0.01 and 0.08, respectively) and LV ejection fraction (AUC = 0.56, 0.69 and 0.69; all P > 0.05) to distinguish AS vs control, AR vs control and AS vs AR groups, respectively. Temporal changes in ԑ-volume characteristics provide novel insight into the haemodynamic cardiac impact of AS and AR. Contrary to traditional measures (i.e. ejection fraction, peak ԑ), these novel measures successfully distinguish between the haemodynamic cardiac impact of AS and AR.

Myocardial Fibrosis in Athletes

Myocardial fibrosis (MF) is a common phenomenon in the late stages of diverse cardiac diseases and is a predictive factor for sudden cardiac death. Myocardial fibrosis detected by magnetic resonance imaging has also been reported in athletes. Regular exercise improves cardiovascular health, but there may be a limit of benefit in the exercise dose-response relationship. Intense exercise training could induce pathologic cardiac remodeling, ultimately leading to MF, but the clinical implications of MF in athletes are unknown. For this comprehensive review, we performed a systematic search of the PubMed and MEDLINE databases up to June 2016. Key Medical Subject Headings terms and keywords pertaining to MF and exercise (training) were included. Articles were included if they represented primary MF data in athletes. We identified 65 athletes with MF from 19 case studies/series and 14 athletic population studies. Myocardial fibrosis in athletes was predominantly identified in the intraventricular septum and where the right ventricle joins the septum. Although the underlying mechanisms are unknown, we summarize the evidence for genetic predisposition, silent myocarditis, pulmonary artery pressure overload, and prolonged exercise-induced repetitive micro-injury as contributors to the development of MF in athletes. We also discuss the clinical implications and potential treatment strategies of MF in athletes.

Effect of Novel, School-Based High-Intensity Interval Training (HIT) on Cardiometabolic Health in Adolescents: Project FFAB (Fun Fast Activity Blasts) - An Exploratory Controlled Before-And-After Trial

Background

Low-volume high-intensity interval training holds promise for cardiometabolic health promotion in adolescents, but sustainable interventions must be practical and engaging. We examined the effect of a school-based multi-activity low-volume high-intensity interval training intervention on adolescents’ cardiometabolic health.

Methods

In an exploratory controlled before-and-after design, 101 adolescents (mean age ± standard deviation [SD] 14.0 ± 0.3 years) were recruited from four schools; two were designated as intervention sites (n = 41), and two as control (n = 60). The intervention comprised 4 to 7 repetitions of 45 s maximal effort exercise (basketball, boxing, dance and soccer drills) interspersed with 90-s rest, thrice weekly for 10 weeks. Outcomes were non-fasting blood lipids and glucose, waist circumference, high sensitivity C-reactive protein, resting blood pressure, physical activity, twenty-metre shuttle-run test performance and carotid artery intima-media thickness. The difference in the change from baseline (intervention minus control) was estimated for each outcome. Using magnitude-based inferences, we calculated the probability that the true population effect was beneficial, trivial, and harmful against a threshold for the minimum clinically important difference of 0.2 between-subject SDs.

Results and Discussion

Mean (± SD) attendance for the intervention (expressed as percentage of available intervention sessions [n = 30]) was 77 ± 13%. Post-intervention, there were likely beneficial effects for triglycerides (-26%; 90% confidence interval -46% to 0%), waist circumference (-3.9 cm; -6.1 cm to -1.6 cm) and moderate-to-vigorous physical activity (+16 min; -5 to 38 min), and a possibly beneficial effect for twenty-metre shuttle-run test performance (+5 shuttles; -1 to 11 shuttles) in intervention participants (vs controls). The role of elevated triglycerides and waist circumference in cardiovascular disease and metabolic syndrome development underlines the importance of our findings. We also demonstrated that school-based low-volume high-intensity interval training can be delivered as intended, thus representing a novel and scalable means of improving aspects of adolescents’ cardiometabolic health.

Trial Registration

ClinicalTrials.gov NCT02626767

Gender differences in ventricular remodeling and function in college athletes, insights from lean body mass scaling and deformation imaging

Several studies suggest gender differences in ventricular dimensions in athletes. Few studies have, however, made comparisons of data indexed for lean body mass (LBM) using allometry. Ninety Caucasian college athletes (mixed sports) who were matched for age, ethnicity, and sport total cardiovascular demands underwent dual-energy x-ray absorptiometry scan for quantification of LBM. Athletes underwent comprehensive assessment of left and right ventricular and atrial structure and function using 2-dimensional echocardiography and deformation imaging using the TomTec analysis system. The mean age of the study population was 18.9 ± 1.9 years. Female athletes (n = 45) had a greater fat free percentage (19.4 ± 3.7%) compared to male athletes (11.5 ± 3.7%). When scaled to body surface area, male had on average 19 ± 3% (p <0.001) greater left ventricular (LV) mass; in contrast, when scaled to LBM, there was no significant difference in indexed LV mass -1.4 ± 3.0% (p = 0.63). Similarly, when allometrically scaled to LBM, there was no significant gender-based difference in LV or left atrial volumes. Although female athletes had mildly higher LV ejection fraction and LV global longitudinal strain in absolute value, systolic strain rate and allometrically indexed stroke volume were not different between genders (1.5 ± 3.6% [p = 0.63] and 0.0 ± 3.7% [p = 0.93], respectively). There were no differences in any of the functional atrial indexes including strain or strain rate parameters. In conclusion, gender-related differences in ventricular dimensions or function (stroke volume) appear less marked, if not absent, when indexing using LBM allometrically.

Comparison of three current sets of electrocardiographic interpretation criteria for use in screening athletes

BACKGROUND

An increasing number of sporting bodies report unacceptably high levels of false-positive ECGs when undertaking pre-participation cardiac screening. To address this issue, modified ECG interpretation criteria have become available for use within athletes.

OBJECTIVE

This study assessed the accuracy of the new 2014 'Refined Criteria' against the 2013 Seattle Criteria and the 2010 European Society of Cardiology (ESC) recommendations in a cohort of Arabic, black and Caucasian athletes.

METHODS

2491 male athletes (1367 Arabic, 748 black and 376 Caucasian) undertook pre-participation screening including a 12-lead ECG, with further investigation(s) upon indication.

RESULTS

Ten athletes (0.4%) were identified with cardiac pathology; seven with hypertrophic cardiomyopathy (HCM; five black and two Arabic) and three Arabs with Wolff-Parkinson-White syndrome (WPW). All three ECG criteria were 100% sensitive identifying all cases of HCM and WPW. The 2014 Refined Criteria reduced (p<0.0001) the prevalence of an abnormal ECG to 5.3% vs 11.6% (Seattle Criteria) and 22.3% (2010 ESC recommendations). The 2014 Refined Criteria significantly (p<0.0001) improved specificity (94.0%) across all ethnicities compared with the Seattle Criteria (87.5%) and ESC recommendations (76.6%). Black athletes continue to present a higher prevalence (p<0.0001) of abnormal ECGs compared with Arabic and Caucasian athletes (10% vs 3.6% and 2.1%).

CONCLUSIONS

The 2014 Refined Criteria for athlete ECG interpretation outperformed both the 2013 Seattle Criteria and the 2010 ESC recommendations by significantly reducing the number of false-positive ECGs in Arabic, black and Caucasian athletes while maintaining 100% sensitivity for serious cardiac pathologies.

Low-volume high-intensity interval training vs continuous aerobic cycling in patients with chronic heart failure: a pragmatic randomised clinical trial of feasibility and effectiveness

OBJECTIVES

The health benefits of high-intensity interval training in cardiac rehabilitation warrant further research. We compared the effectiveness of low-volume high-intensity interval training vs continuous aerobic exercise training in chronic heart failure.

DESIGN/SETTINGS

Unblinded, two arm parallel design with random assignment to exercise interventions in out-patient hospital rehabilitation gym.

METHODS

Patients with signs of chronic heart failure and ejection fraction < 45%, (mean age: 59.1 years (standard deviation (SD) 8.6); 3 women) completed 6 months of exercise using continuous aerobic exercise training (n = 9) or high-intensity interval training (n = 8). Cardiorespiratory fitness was determined during cycle ergometry using respiratory gas exchange analysis. Functional capacity was assessed via sit-to-stand and gait speed. Quality of life was assessed using the MOS Short-Form 36 and Minnesota living with heart failure questionnaires. Cardiac autonomic regulation was assessed using Heart Rate Variability.

RESULTS

Analysis of Covariance revealed significant time effects but no group × time interactions for exercise and functional capacity outcomes. Peak oxygen uptake (VO2peak) improved by a mean of 14.9% (SD 16.3%) from baseline and by 22% (SD 28.3) at ventilatory threshold in both groups. Sit-to-stand (11.9 (SD 11%)) and gait speed (16.0 (SD 19%)) improved similarly in both groups. No changes in quality of life or heart rate variability were noted. Training adaptations in high-intensity interval training were achieved despite a significantly reduced time commitment and total work volume compared to continuous aerobic exercise training.

CONCLUSION

Low-volume high-intensity interval training is a feasible and well tolerated training modality in cardiac rehabilitation settings, but is not more effective than continuous aerobic exercise training.

Systematic echocardiography is not efficacious when screening an ethnically diverse cohort of athletes in West Asia

BACKGROUND

The clinical and economic value of including systematic echocardiography (ECHO) alongside the 12-lead electrocardiograpm (ECG) when undertaking pre-participation screening in athletes has not been examined, yet several sporting organistations recommend its inclusion.

DESIGN

To examine the efficacy of systematic ECHO alongside the ECG, to identify sudden cardiac death (SCD) disease and to provide a cost-analysis of a government-funded pre-participation screening programme.

METHODS

A total 1628 athletes presented for cardiological consultation, ECG, and ECHO as standard, with further cardiac examinations performed if necessary to confirm or exclude pathology. The efficacy of systematic ECHO was compared to an ECG-led programme, with ECHO reserved as a follow-up examination.

RESULTS

To screen 1628 athletes with ECG and ECHO cost US$743,996. There were 54 24-h-blood pressure/ECG Holter recordings, 62 exercise tests, 25 CMRs, two electrophysiological studies, and two genetic tests, which cost US$67,734: total US$811,730. Eight athletes (0.5%) were identified with hypertrophic cardiomyopathy (HCM) and two (0.1%) with Wolff-Parkinson-White syndrome. The cost per identifed athlete was US$81,173. All 10 athletes presented an abnormal ECG. No athlete diagnosed with HCM was identified by ECHO in isolation. When adopting a ECG-led screening protocol, 15% of athletes required ECHO as a follow-up examination, resulting in a US$380,600 cost reduction (47% saving), with the cost per diagnosis reduced to US$43,113.

CONCLUSIONS

Athletes diagnosed with a disease associated with SCD were identified via an abnormal ECG and/or physical examination, personal symptoms, or family history. Screening athletes with systematic ECHO is not economically or clinically effective.

Significance of deep T-wave inversions in asymptomatic athletes with normal cardiovascular examinations: practical solutions for managing the diagnostic conundrum

Preparticipation screening programmes for underlying cardiac pathologies are now commonplace for many international sporting organisations. However, providing medical clearance for an asymptomatic athlete without a family history of sudden cardiac death (SCD) is especially challenging when the athlete demonstrates particularly abnormal repolarisation patterns, highly suggestive of an inherited cardiomyopathy or channelopathy. Deep T-wave inversions of ≥ 2 contiguous anterior or lateral leads (but not aVR, and III) are of major concern for sports cardiologists who advise referring team physicians, as these ECG alterations are a recognised manifestation of hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC). Subsequently, inverted T-waves may represent the first and only sign of an inherited heart muscle disease, in the absence of any other features and before structural changes in the heart can be detected. However, to date, there remains little evidence that deep T-wave inversions are always pathognomonic of either a cardiomyopathy or an ion channel disorder in an asymptomatic athlete following long-term follow-up. This paper aims to provide a systematic review of the prevalence of T-wave inversion in athletes and examine T-wave inversion and its relationship to structural heart disease, notably HCM and ARVC with a view to identify young athletes at risk of SCD during sport. Finally, the review proposes clinical management pathways (including genetic testing) for asymptomatic athletes demonstrating significant T-wave inversion with structurally normal hearts.

Does echocardiography accurately reflect CMR-determined changes in left ventricular parameters following exercise training? A prospective longitudinal study

Cardiac adaptation in response to exercise has historically been described using echocardiography. Cardiac magnetic resonance (CMR), however, has evolved as a preferred imaging methodology for cardiac morphological assessment. While direct imaging modality comparisons in athletes suggest that large absolute differences in cardiac dimensions exist, it is currently unknown whether changes in cardiac morphology in response to exercise training are comparable when using echocardiography and CMR. Twenty-two young men were randomly assigned to undertake a supervised and intensive endurance or resistance exercise-training program for 24 wk. Echocardiography and CMR assessment of left ventricular (LV) mass, LV end-diastolic volume, internal cavity dimensions, and wall thicknesses were completed before and after training. At baseline, pooled data for all cardiac parameters were significantly different between imaging methods, while LV mass (r = 0.756, P < 0.001) and volumes (LV end-diastolic volume, r = 0.792, P < 0.001) were highly correlated across modalities. Changes in cardiac morphology data with exercise training were not significantly related when echocardiographic and CMR measures were compared. For example, posterior wall thickness increased by 8.3% (P < 0.05) when assessed using echocardiography, but decreased by 2% when using CMR. In summary, echocardiography and CMR imaging modalities produce findings that differ with respect to changes in cardiac size and volume following exercise training.

Periodic limb movements in sleep contribute to further cardiac structure abnormalities in hemodialysis patients with restless legs syndrome

STUDY OBJECTIVES

In hemodialysis (HD) patients, restless legs syndrome (RLS) and periodic limb movements in sleep (PLMS) constitute common sleep disorders. Recent findings indicate a role for PLMS as a risk factor in the development of new or the aggravation of existing cardiovascular disease. The aim of the current study was to investigate the association of PLMS with indices of cardiac morphology and function in HD patients with RLS as a potential pathway by which PLMS could alter cardiovascular risk.

METHODS

Based on PLMS diagnosis by an overnight polysomnographic evaluation, 19 stable HD-RLS patients were divided into the PLMS group (n = 10) and the non-PLMS group (n = 9). During the overnight assessment, nocturnal blood pressure (BP) indices were also assessed. Left ventricular (LV) dimensions were examined by M-mode echocardiography, whereas LV diastolic function was evaluated by conventional Doppler and tissue Doppler imaging the following day.

RESULTS

LV internal diameter in diastole was significantly increased in the PLMS group (4.96 ± 0.61 vs 4.19 ± 0.48 cm, p = 0.007), leading to a significantly increase in LV mass (202 ± 52 vs 150 ± 37 g, p = 0.026). In contrast, no between group differences were observed in diastolic function indices (p > 0.05).

CONCLUSIONS

These are the first data to associate severe PLMS with further LV structure abnormalities in HD patients with RLS.

Do big athletes have big hearts? Impact of extreme anthropometry upon cardiac hypertrophy in professional male athletes

AIM

Differentiating physiological cardiac hypertrophy from pathology is challenging when the athlete presents with extreme anthropometry. While upper normal limits exist for maximal left ventricular (LV) wall thickness (14 mm) and LV internal diameter in diastole (LVIDd, 65 mm), it is unknown if these limits are applicable to athletes with a body surface area (BSA) >2.3 m(2).

PURPOSE

To investigate cardiac structure in professional male athletes with a BSA>2.3 m(2), and to assess the validity of established upper normal limits for physiological cardiac hypertrophy.

METHODS

836 asymptomatic athletes without a family history of sudden death underwent ECG and echocardiographic screening. Athletes were grouped according to BSA (Group 1, BSA>2.3 m(2), n=100; Group 2, 2-2.29 m(2), n=244; Group 3, <1.99 m(2), n=492).

RESULTS

There was strong linear relationship between BSA and LV dimensions; yet no athlete with a normal ECG presented a maximal wall thickness and LVIDd greater than 13 and 65 mm, respectively. In Group 3 athletes, Black African ethnicity was associated with larger cardiac dimensions than either Caucasian or West Asian ethnicity. Three athletes were diagnosed with a cardiomyopathy (0.4% prevalence); with two athletes presenting a maximal wall thickness >13 mm, but in combination with an abnormal ECG suspicious of an inherited cardiac disease.

CONCLUSION

Regardless of extreme anthropometry, established upper limits for physiological cardiac hypertrophy of 14 mm for maximal wall thickness and 65 mm for LVIDd are clinically appropriate for all athletes. However, the abnormal ECG is key to diagnosis and guides follow-up, particularly when cardiac dimensions are within accepted limits.

Conduit diameter and wall remodeling in elite athletes and spinal cord injury

PURPOSE

This study aimed to investigate localized and systemic effects of chronic exercise and inactivity on conduit artery remodeling in humans.

METHODS

We recruited elite athletes engaged in predominantly lower limb (LL runners/cyclists, n = 10) or upper limb (UL canoe paddlers, n = 12) exercise and matched able-bodied, recreationally active, controls (C, n = 16). We also studied wheelchair controls (spinal cord injury, n = 9) and athletes (spinal cord injury, n = 1; spina bifida, n = 4). Carotid, brachial, and superficial femoral (SF) artery diameter and wall thickness were assessed using high-resolution ultrasound.

RESULTS

Brachial diameters were significantly larger in UL and wheelchair users (athletes and controls) compared with C (both P < 0.05). SF artery diameter in wheelchair controls was significantly smaller compared with the other groups, with LL athletes having significantly greater lumen diameter than controls (both P < 0.05). In all arteries, a lower wall thickness was found in able-bodied athletes compared with C, including wheelchair athletes compared with wheelchair controls (P < 0.001). In the SF artery, wall-to-lumen-ratio was significantly lower in able-bodied athletes and higher in wheelchair controls compared with able-bodied controls (P < 0.001). In the brachial and carotid arteries, able-bodied and wheelchair athletes demonstrated lower wall-to-lumen-ratio than less active wheelchair controls and able-bodied controls (P < 0.001).

CONCLUSIONS

These findings suggest that remodeling of the arterial wall occurs systemically in response to exercise training and is unrelated to exercise type in humans. Conversely, localized effects are evident with respect to the effect of exercise on arterial diameter. These findings have implications for our understanding of the effects of exercise on arterial structure and function in humans.

The kinetics of highly sensitive cardiac troponin T release after prolonged treadmill exercise in adolescent and adult athletes

The nature and kinetics of postexercise cardiac troponin (cTn) appearance is poorly described and understood in most athlete populations. We compared the kinetics of high-sensitivity cTn T (hs-cTnT) after endurance running in training-matched adolescents and adults. Thirteen male adolescent (mean age: 14.1 ± 1.1 yr) and 13 male adult (24.0 ± 3.6 yr) runners performed a 90-min constant-load treadmill run at 95% of ventilatory threshold. Serum hs-cTnT levels were assessed preexercise, immediately postexercise, and at 1, 2, 3, 4, 5, 6, and 24 h postexercise. Serum NH2-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels were recorded preexercise and 3, 6, and 24 h postexercise. Left ventricular function was assessed preexercise, immediately postexercise, and 6 h postexercise. Peak hs-cTnT occurred at 3–4 h postexercise in all subjects, but was substantially higher ( P < 0.05) in adolescents [median (range): 211.0 (11.2–794.5) ng/l] compared with adults [median (range): 19.1 (9.7–305.6) ng/l]. Peak hs-cTnT was followed by a rapid decrease in both groups, although adolescent data had not returned to baseline at 24 h. Substantial interindividual variability was noted in peak hs-cTnT, especially in the adolescents. NT-pro-BNP was significantly elevated postexercise in both adults and adolescents and remained above baseline at 24 h in both groups. In both groups, left ventricular ejection fraction and the ratio of early-to-atrial peak Doppler flow velocities were significantly decreased immediately postexercise. Peak hs-cTnT was not related to changes in ejection fraction, ratio of early-to-atrial peak Doppler flow velocities, or NT-pro-BNP. The present data suggest that postexercise hs-cTnT elevation 1) occurred in all runners, 2) peaked 3–4 h postexercise, and 3) the peak hs-cTnT concentration after prolonged exercise was higher in adolescents than adults.

Growth of left ventricular mass with military basic training in army recruits

Exercise-induced left ventricular hypertrophy is well documented, but whether this occurs merely in line with concomitant increases in lean body mass is unclear.

PURPOSE

Our aim was to model the extent of left ventricular hypertrophy associated with increased lean body mass attributable to an exercise training program.

METHODS

Cardiac and whole-body magnetic resonance imaging was performed before and after a 10-wk intensive British Army basic training program in a sample of 116 healthy Caucasian males (aged 17-28 yr). The within-subjects repeated-measures allometric relationship between lean body mass and left ventricular mass was modeled to allow the proper normalization of changes in left ventricular mass for attendant changes in lean body mass. To linearize the general allometric model (Y=aXb), data were log-transformed before analysis; the resulting effects were therefore expressed as percent changes. We quantified the probability that the true population increase in normalized left ventricular mass was greater than a predefined minimum important difference of 0.2 SD, assigning a probabilistic descriptive anchor for magnitude-based inference.

RESULTS

The absolute increase in left ventricular mass was 4.8% (90% confidence interval=3.5%-6%), whereas lean body mass increased by 2.6% (2.1%-3.0%). The change in left ventricular mass adjusted for the change in lean body mass was 3.5% (1.9%-5.1%), equivalent to an increase of 0.25 SD (0.14-0.37). The probability that this effect size was greater than or equal to our predefined minimum important change of 0.2 SD was 0.78-likely to be important.

CONCLUSIONS

After correction for allometric growth rates, left ventricular hypertrophy and lean body mass changes do not occur at the same magnitude in response to chronic exercise.