Heart rate variability and repolarization characteristics in symptomatic and asymptomatic Brugada syndrome.

AIM: Modulation of ST-segment elevation (STE) and tachyarrhythmic events by the autonomic nervous system (ANS) has been reported in patients with Brugada syndrome (BS). This study examined and compared the autonomic characteristics and STE in symptomatic vs. asymptomatic patients with BS. METHODS AND RESULT: We studied 40 symptomatic and 78 asymptomatic patients (mean age = 46.1 ± 13.7 years; 88 men) who underwent 24 h, 12-lead electrocardiograms, and exercise and a head-up tilt tests. Heart rate variability was examined and STE was measured at 5 points between 100 and 140 ms after the onset of 1 min averaged QRS complexes, and the type 1 Brugada pattern was automatically identified. 'Type 1 Brugada burden' was the percentage of averaged type 1 complexes. All measurements were made over 24 h, and during day and night times. During daytime, the variation coefficients of standard deviation of normal-to-normal intervals were 39.0 ± 12.3 vs. 34.1 ± 14.5 ms (P< 0.05) and high frequency normalized units were 39.9 ± 16.9 vs. 33.9 ± 16.2% (P< 0.05) in symptomatic vs. asymptomatic patients, respectively. ST-segment elevation was similar in symptomatic and asymptomatic patients at all time points. The type 1 Brugada burden in V2 was 38.7 ± 33.6% in the symptomatic vs. 24.3 ± 35.2% in the asymptomatic sample, a statistically non-significant difference. CONCLUSION: This analysis of ANS did not identify sensitive predictors of arrhythmic events in patients with BS. We observed, however, greater fluctuations in sinus node response to ANS in symptomatic patients. The type 1 Brugada electrocardiographic pattern was not as reliable a predictor of arrhythmic risk as previously reported.

Recognition and significance of pathological T-wave inversions in athletes.

BACKGROUND: Pathological T-wave inversion (PTWI) is rarely observed on the ECG of healthy athletes, whereas it is common in patients with certain cardiac diseases. All ECG interpretation guidelines for use within athletes state that PTWI (except in leads aVR, III and V1 and in V1-V4 when preceded by domed ST segment in asymptomatic Afro-Caribbean athletes only) cannot be considered a physiological adaptation. The aims of the present study were to prospectively determine the prevalence of cardiac pathology in athletes presenting with PTWI, and to examine the efficacy of cardiac magnetic resonance in the work-up battery of further examinations. METHODS AND RESULTS: Athletes presenting with PTWI (n=155) were investigated with clinical examination, ECG, echocardiography, exercise testing, 24h Holter ECG, and cardiac magnetic resonance. Cardiac disease was established in 44.5% of athletes, with hypertrophic cardiomyopathy (81%) the most common pathology. Echocardiography was abnormal in 53.6% of positive cases, and cardiac magnetic resonance identified a further 24 athletes with disease. Five athletes (7.2%) considered normal on initial presentation subsequently expressed pathology during follow-up. Familial history of sudden cardiac death and ST-segment depression associated with PTWI were predictive of cardiac disease. CONCLUSIONS: PTWI should be considered pathological in all cases until proven otherwise, because it was associated with cardiac pathology in 45% of athletes. Despite echocardiography identifying pathology in half of these cases, cardiac magnetic resonance must be considered routine in athletes presenting with PTWI with normal echocardiography. Although exclusion from competitive sport is not warranted in the presence of normal secondary examinations, annual follow-up is essential to ascertain possible disease expression.

Cardiac adaptation to exercise in adolescent athletes of African ethnicity: an emergent elite athletic population.

BACKGROUND/AIMS: Adult black athletes (BA) exhibit left ventricular hypertrophy (LVH) on echocardiography and marked ECG repolarisation changes resembling those observed in hypertrophic cardiomyopathy (HCM). Limited data are available for adolescent BA, the group most vulnerable to exercise-related sudden cardiac death. METHODS: Between 1996 and 2011, 245 male and 84 female adolescent BA from a wide variety of sporting disciplines underwent cardiac evaluation including ECG and echocardiography. Athletes exhibiting T-wave inversions and/or echocardiographic LVH were investigated further for quiescent cardiomyopathies. Results were compared with 903 adolescent white athletes (WA) and 134 adolescent sedentary black controls (BC). RESULTS: LVH on echocardiography was present in 7% of BA compared to only 0.6% of WA and none of the BC. In the very young (<16 years), 5.5% of BA, but none of the WA, demonstrated LVH. Within the BA group, LVH was more prevalent in men compared to women (9% vs 1.2%, p=0.012). T-wave inversions were present in 22.8% BA, 4.5% WA and 13.4% BC. T-wave inversions in BA occurred with similar frequency in men and women and were predominantly confined to leads V1-V4. T-wave inversions in the lateral leads, commonly associated with cardiomyopathies, were present in 2.4% of BA. On a further evaluation and mean follow-up of 8.3 years, none of the athletes exhibited HCM. CONCLUSIONS: Athletic training has a pronounced effect on adolescent BA. Black athletes as young as 14 years of age may exhibit left ventricular wall thicknesses of 15 mm and marked repolarisation changes resembling HCM. Male and female BA demonstrate a high prevalence of T-wave inversions.

Impact of ethnicity upon cardiovascular adaptation in competitive athletes: relevance to preparticipation screening.

Regular participation in intensive physical exercise is associated with several structural and electrophysiological cardiac adaptations that enhance diastolic filling and facilitate a sustained increase in the cardiac output that is fundamental to athletic excellence. Such cardiac adaptations are collectively referred to as the 'Athlete's Heart' and are frequently reflected on the 12-lead ECG and imaging studies. Thorough knowledge relating to exercise-associated cardiovascular adaptation is imperative for the purposes of differentiating physiological adaptation from cardiac pathology, since an erroneous diagnosis of cardiac disease has potentially serious consequences for the athlete's physical, psychological, social and financial well-being. The majority of studies investigating the cardiovascular adaptation to exercise are based on cohorts of Caucasian athletes. However, there is mounting evidence that ethnicity is an important determinant of the objective manifestations of cardiovascular adaptation to exercise. The most pronounced paradigm of ethnically distinct cardiovascular adaptation to exercise stems from athletes of African/Afro-Caribbean descent, who exhibit a significantly higher prevalence of repolarisation anomalies and left ventricular hypertrophy, compared to Caucasian athletes; the differentiation between athlete's heart and hypertrophic cardiomyopathy is particularly challenging in this ethnic group. The extrapolation of ECG and echocardiographic criteria used to diagnose potentially serious cardiac disorders in Caucasian athletes to the African/Afro-Caribbean athlete population would result in an unacceptable number of unnecessary investigations and increased risk of false disqualification from competitive sport. Accurate interpretation of the athlete's ECG and echocardiogram is crucial, particularly when one considers the continuous expansion of preparticipation screening programmes. This review attempts to highlight ethnically determined differences in cardiovascular adaptation to exercise and provides a practical guide for the interpretation of baseline investigations in athletes of diverse ethnic backgrounds.

The prevalence, distribution, and clinical outcomes of electrocardiographic repolarization patterns in male athletes of African/Afro-Caribbean origin.

AIMS: Athletic training in male black athletes (BAs) is associated with marked ECG repolarization changes that overlap with hypertrophic cardiomyopathy (HCM). Differentiating between the two entities is prudent since BAs exhibit a higher prevalence of exercise-related sudden death from HCM compared with white athletes (WAs). METHODS AND RESULTS: Between 1996 and 2010, 904 BAs underwent serial cardiac evaluations including ECG and echocardiography. Athletes exhibiting T-wave inversions were investigated further for HCM. Results were compared with 1819 WAs, 119 black controls (BCs), and 52 black HCM patients. Athletes were followed up for 69.7 ± 29.6 months. T-wave inversions were present in 82.7% HCM patients, 22.8% BAs, 10.1% BCs, and 3.7% WAs. In athletes, the major determinant of T-wave inversions was black ethnicity. T-wave inversions in BAs (12.7%) were predominantly confined to contiguous anterior leads (V1-V4). Only 4.1% of BAs exhibited T-wave inversions in the lateral leads. In contrast, both BCs and HCM patients exhibited lower prevalence of T-wave inversions in leads V1-V4 (4.2 and 3.8%, respectively) with most T-wave inversions in HCM patients (76.9%) involving the lateral leads. During follow-up one BA survived cardiac arrest and two athletes (one BA, one WA) were diagnosed with HCM. All three exhibited T-wave inversions in the lateral leads. CONCLUSIONS: T-wave inversions in leads V1-V4 appear to represent an ethnic variant of 'athlete's heart'. Conversely, T-wave inversions in the lateral leads may represent the initial expression of underlying cardiomyopathy and merit further evaluation and regular surveillance.

Impact of long-lasting moderate-intensity stage cycling event on cardiac function in young female athletes: A case study.

PURPOSE: Effects of intense and/or prolonged exercise have been studied extensively in male athletes. Nevertheless, data are scare on the effect of long duration events on cardiac function in female athletes. Our aim was to investigate the effect of a long-lasting moderate-intensity stage cycling event on cardiac function of young female athletes. METHODS: Seven well-trained female cyclists were included. They completed a cycling event of 3529 km on 23 days. All underwent an echocardiography on 6 time-points (baseline and at the arrival of day (D) 3, 7, 12, 13 and 23). Cardiac function was assessed by conventional echocardiography, tissue Doppler imaging and speckle tracking techniques. Daily exercise load was determined by heart rate (HR), power output and rate of perceived exertion data (RPE, Borg scale). RESULTS: All stages were mainly done at moderate intensity (average HR: 65% of maximal, average aerobic power output: 36% of maximal, average RPE: 4). Resting HR measured at the time of echocardiography did not vary during the event. Resting cardiac dimensions did not significantly change during the 23 days of cycling. No significant modification of cardiac function, whatever the studied cavity, were observed all along the event. CONCLUSION: The results suggest that, in the context of our case study, the long-lasting moderate-intensity stage cycling event was not associated with cardiac function alteration. Nevertheless, we must be careful in interpreting them due to the limits of an underpowered study.

Importance of ventricular longitudinal function in chronic heart failure.

AIMS: Despite its immediate relevance, cardiopulmonary exercise testing (CPET) is infrequently performed in the presence of chronic heart failure (CHF). Previous studies of patients suffering from CHF have found a closer correlation between exercise capacity and measurements of diastolic than systolic ventricularfunction. We examined the correlation between echocardiographic measurements and (i) results of CPET and (ii) cardiovascular prognosis. METHODS AND RESULTS: We performed resting two-dimensional echocardiograms and CPET in 140 patients with CHF (mean age = 61 ± 13 years, 111 men). The underlying heart disease was ischaemic in 48 patients (34%). They were followed for a mean of 38 months (range 28-52). The mean left ventricular (LV) ejection fraction (EF) was 30 ± 9% and peak VO2 17.2 ± 6.5 mL/kg/min. LVEF correlated weakly with peak VO2 (r = 0.21), while systolic and early diastolic LV longitudinal function correlated best [early diastolic peak velocity at the mitral annulus (E'): r = 0.38; global longitudinal strain (GLS): r = -0.4; P <0.001 for both]. By multiple variable regression analysis, the best prediction of peak VO2 was derived from a model based on age, mitral annulus end-diastolic peak velocity (A'), GLS, right ventricular (RV) systolic strain, and left atrial systolic strain (r² = 0.57; P <0.0001). The two best independent predictors of adverse cardiovascular events at 28 months were GLS (odds ratio 1.31, P <0.001; prognostic cut-off = -8%) and RV systolicstrain (odds ratio 1.05, P =0.01; prognostic cut-off = -22%). CONCLUSION: Resting RV and LV longitudinal functions were reliable predictors of adverse cardiovascular events and correlated moderately with, but not took to the place of, CPET measurements.

Improved diagnosis of post-operative myocardial infarction by contrast echocardiography after coronary artery bypass graft surgery.

OBJECTIVE: Contrast echocardiography is a more accurate means of assessment of left ventricular (LV) regional motion compared with non-enhanced echocardiography. Despite new tests, the diagnosis of post-operative myocardial infarction (MI) remains difficult. The aim of this study was to determine whether contrast echocardiography can facilitate this diagnosis. METHODS: We performed standard and contrast echocardiography in 79 consecutive patients before and up to 10 days after they underwent isolated coronary artery bypass graft (CABG) surgery. RESULTS: The post-operative intra- and interobserver reproducibility of echocardiographic measurements of the LV ejection fraction and wall motion score was significantly higher with than without contrast enhancement. The proportion of non-visualized LV myocardial segments was significantly greater with non-enhanced (6.6%) than with contrast (0.3%) echocardiography (P< 0.0001). The mean peak serum cardiac troponin (cTnI) concentration was significantly higher in the group of patients with new wall motion abnormalities detected with contrast-enhanced echocardiography. A correlation was found (r = -0.43, P< 0.01) between peak cTnI and changes in wall motion score only when a contrast agent was used. CONCLUSION: Contrast echocardiography facilitated the detection of new LV wall motion abnormalities after CABG. This observation, added to other markers, might facilitate the diagnosis of post-operative MI.

Exercise-Induced Cardiac Fatigue in Soldiers Assessed by Echocardiography.

Background: Echocardiographic signs of exercise-induced cardiac fatigue (EICF) have been described after strenuous endurance exercise. Nevertheless, few data are available on the effects of repeated strenuous exercise, especially when associated with other constraints as sleep deprivation or mental stress which occur during military selection boot camps. Furthermore, we aimed to study the influence of experience and training level on potential EICF signs. Methods: Two groups of trained soldiers were included, elite soldiers from the French Navy Special Forces (elite; n = 20) and non-elite officer cadets from a French military academy (non-elite; n = 38). All underwent echocardiography before and immediately after exposure to several days of uninterrupted intense exercise during their selection boot camps. Changes in myocardial morphology and function of the 4 cardiac chambers were assessed. Results: Exercise-induced decrease in right and left atrial and ventricular functions were demonstrated with 2D-strain parameters in both groups. Indeed, both atrial reservoir strain, RV and LV longitudinal strain and LV global constructive work were altered. Increase in LV mechanical dispersion assessed by 2D-strain and alteration of conventional parameters of diastolic function (increase in E/e' and decrease in e') were solely observed in the non-elite group. Conventional parameters of LV and RV systolic function (LVEF, RVFAC, TAPSE, s mitral, and tricuspid waves) were not modified. Conclusions: Alterations of myocardial functions are observed in soldiers after uninterrupted prolonged intense exercise performed during selection boot camps. These alterations occur both in elite and non-elite soldiers. 2D-strain is more sensitive to detect EICF than conventional echocardiographic parameters.