Exercise-induced increases in cardiac troponins and prothrombotic markers

Utility of cardiac biomarkers in sports medicine: Focusing on troponin, natriuretic peptides, and hypoxanthine

Evidence-based consensus suggests that physical activity and regular exercise training can reduce modifiable risk factors as well as rate of mortality and morbidity in patients with chronic diseases, such as cardiovascular disease (CVD), diabetes, obesity and cancer. Conversely, long-term exercise training and drastic increase in vigorous physical activity may also cause acute cardiovascular events (e.g. acute myocardial infarction) and deleterious cardiac remodeling, particularly when exercise is performed by unfit or susceptible individuals. There is a reversed J-shaped hormesis-like curve between the duration and intensity of exercise and level of CVD risks. Therefore, it is important for an early detection of cardiac injuries in professional and amateur athletes. Under this context, this article focuses on the use of biomarker testing, an indispensable component in the current clinical practices especially in Cardiology and Oncology. We attempt to justify the importance of using circulating biomarkers in routine practices of Sports Medicine for an objective assessment of CVD events following exercise. Special attentions are dedicated to three established or emerging cardiac biomarkers (i.e. cardiac troponins, natriuretic peptides, hypoxanthine) for myocardial tissue hypoxia/ischemia events, muscle stress, and the consequent cellular necrotic injury. Based on these focused analyses, we propose use of circulating biomarker testing in both laboratory and point-of-care settings with an increasingly broader involvement or participation of team physicians, trainers, coaches, primary care doctors, as well as educated athlete community. This diagnostic approach may improve the quality of medical surveillance and preventive measures on exercise-related CVD risks/outcomes.

Intraoperative Troponin Elevation in Liver Transplantation Is Independently Associated With Mortality: A Prospective Observational Study

Intraoperative factors implicated in postoperative mortality after liver transplantation (LT) are poorly understood. Because LT is a particularly demanding procedure, we hypothesized that intraoperative myocardial injury may be frequent and independently associated with early postoperative outcomes. We aimed to determine the association between intraoperative high-sensitivity troponin (hsTn) elevation during LT and 30-day postoperative mortality. A total of 203 adult patients undergoing LT were prospectively included in the cohort and followed during 1 year. Advanced hemodynamic parameters and serial high-sensitivity troponin T (hsTnT) measurements were assessed at 6 intraoperative time points. The optimal hsTnT cutoff level for intraoperative troponin elevation (ITE) was identified. Patients were classified into 2 groups according to the presence of ITE. Independent impact of ITE on survival was assessed through survival curves and multivariate Cox regression analysis. Intraoperative cardiac function was compared between groups. Troponin levels increased early during surgery in the ITE group. Troponin values at abdominal closure were associated with 30-day mortality (area under the receiver operating caracteristic curve, [AUROC], 0.73; P = 0.005). Patients with ITE showing values of hsTnT ≥61 ng/L at abdominal closure presented higher 30-day mortality (29.6% versus 3.4%; P < 0.001). ITE was independently associated with 30-day mortality (hazard ratio, 3.8; 95% confidence interval, 1.1-13.8; P = 0.04) and with worse overall intraoperative cardiac function. The hsTnT upper reference limit showed no discriminant capacity during LT. Intraoperative myocardial injury identified by hsTn elevation is frequently observed during LT, and it is associated with myocardial dysfunction and short-term mortality. Determinations of hsTn may serve as a valuable intraoperative monitoring tool during LT.

Troponin elevation in the setting of exercise-induced rhabdomyolysis in an athletic teenager

Troponin levels are often obtained when chest pain is evaluated in the paediatric emergency department. Elevations in troponin levels can be due to different causes, and it is important to fully understand all of these possible causes to help streamline further evaluation and therapy. We present the case of a teenager who had two episodes of troponin elevation in the setting of rhabdomyolysis.

Troponin release after exertional vasovagal syncope

Troponin release following exertional vasovagal syncope has not previously been reported. A young man was investigated after being admitted twice with exertional syncope, each time followed by a 10-fold spike in troponin I over 24 h. Treadmill exercise tests reproduced his symptoms and demonstrated a vasovagal mechanism. During recovery, despite lying supine, he remained hypotensive for 5 min, with profound bradycardia and ST segment depression. We suspected that intense cardiovagal neural activity may have caused the troponin leak.

[Ventricular arrythmia and sport practice: A Gallavardin's ventricular tachycardia during exercice in healthy heart, about a case and review of the literature]

Regular physical exercice has undeniable cardiovascular benefits and improves life expectancy. This benefice seems limited to moderate intensity exercises. Intense and chronic physical exercice would lead to heart structural changes. For a long time, knowledge of these cardiac effects seemed limited to the left ventricle. Since more authors have shown that right ventricle is vulnerability to the effects of intense chronic training. We report a Gallavardin-type ventricular stress tachycardia in a young with healthy hearted; in whom a right infundibular arrhythmogenic focus has been found in the absence of structural alteration of the right ventricle. Intense athletic activity may reveal a latent arrhythmogenic focus through sympathetic activation. Ablation was the preferred therapeutic strategy, preferred to drug therapy and derived from an analysis of risk-benefit ratios.

High-sensitivity cardiac troponin T in stable patients undergoing pharmacological stress testing

BACKGROUND

Acute changes in high-sensitivity troponin T (hs-TnT) are induced by myocardial ischemia during exercise stress testing, but there are no reports of pharmacological stress testing.

HYPOTHESIS

The pattern of troponin release by myocardial ischemia-induced pharmacological stress testing differs according to the ischemic burden in stable patients.

METHODS

In total, 250 patients with suspected coronary artery disease underwent pharmacological stress magnetic resonance imaging (MRI). The amount and degree of myocardial ischemia on MRI and ischemic outcomes at 6 months were determined. hs-TnT levels were measured at baseline and 1 and 3 hours after testing. The 6-month clinical outcome was prespecified.

RESULTS

Fifty-one patients had moderate to severe myocardial ischemia (group A), and 199 patients had no or mild myocardial ischemia (group B). hs-TnT levels were significantly higher in group A than B at baseline (11 vs 8 pg/mL, P = 0.016) and at 1 hour (12 vs 8 pg/mL, P = 0.009) and 3 hours after testing (12 vs 9 pg/mL, P = 0.012). Baseline hs-TnT levels of ≥14 pg/mL showed a 43% sensitivity and 77% specificity in predicting moderate to severe ischemia by MRI (P = 0.03; area under the curve: 0.608, P = 0.017). Patients administered dobutamine had a higher acute change in hs-TnT levels 3 hours after testing than did those administered adenosine (21 vs 0 pg/mL, P < 0.001). There was a trend toward a higher incidence of myocardial infarction in patients with baseline hs-TnT levels of ≥14 pg/mL.

CONCLUSIONS

hs-TnT levels are significantly higher in patients with moderate to severe than no or mild myocardial ischemia.

Does a run/walk strategy decrease cardiac stress during a marathon in non-elite runners?

OBJECTIVES

Although alternating run/walk-periods are often recommended to novice runners, it is unclear, if this particular pacing strategy reduces the cardiovascular stress during prolonged exercise. Therefore, the aim of the study was to compare the effects of two different running strategies on selected cardiac biomarkers as well as marathon performance.

DESIGN

Randomized experimental trial in a repeated measure design.

METHODS

Male (n=22) and female subjects (n=20) completed a marathon either with a run/walk strategy or running only. Immediately after crossing the finishing line cardiac biomarkers were assessed in blood taken from the cubital vein. Before (-7 days) and after the marathon (+4 days) subjects also completed an incremental treadmill test.

RESULTS

Despite different pacing strategies, run/walk strategy and running only finished the marathon with similar times (04:14:25±00:19:51 vs 04:07:40±00:27:15 [hh:mm:ss]; p=0.377). In both groups, prolonged exercise led to increased B-type natriuretic peptide, creatine kinase MB isoenzyme and myoglobin levels (p<0.001), which returned to baseline 4 days after the marathon. Elevated cTnI concentrations were observable in only two subjects. B-type natriuretic peptide (r=-0.363; p=0.041) and myoglobin levels (r=-0.456; p=0.009) were inversely correlated with the velocity at the individual anaerobic threshold. Run/walk strategy compared to running only reported less muscle pain and fatigue (p=0.006) after the running event.

CONCLUSIONS

In conclusion, the increase in cardiac biomarkers is a reversible, physiological response to strenuous exercise, indicating temporary stress on the myocyte and skeletal muscle. Although a combined run/walk strategy does not reduce the load on the cardiovascular system, it allows non-elite runners to achieve similar finish times with less (muscle) discomfort.

Blood cardiac troponin in toxic myocardial injury: archetype of a translational safety biomarker

A translational safety biomarker for toxic myocardial injury is needed in drug discovery and development. This need reflects the increasing recognition of occurrence of cardiotoxicities, prior lack of preclinical blood biomarkers for toxic cardiac injury, introduction of troponin as a biomarker, and regulatory and industry drivers. Cardiac troponin is considered the gold-standard biomarker in humans for cardiac injury due to ischemic injury and drug toxicity. It has been demonstrated to correlate highly with histopathological extent of injury, degree of impairment of cardiac function, and prognosis. Numerous studies have now clearly demonstrated that both cardiac troponin T and cardiac troponin I are sensitive and specific biomarkers of cardiac injury in laboratory animals. Their use is highly recommended for incorporation into preclinical drug-safety studies, especially whenever there is any history of cardiac effect in prior studies with a compound of the same or similar chemical or pharmacological class. The main caveats with respect to cross-species use of specific cardiac troponin assays are the need for species-specific validation, definition of cut-offs based on relevant assessments of imprecision and reference ranges or concurrent controls, and knowledge of the species-dependent kinetics of release into, and clearance from, the blood. Future development of high-sensitivity assays should determine whether minimal increases below a threshold concentration of troponin might reflect reversible myocardial effects.

Can high altitude influence cytokines and sleep?

The number of persons who relocate to regions of high altitude for work, pleasure, sport, or residence increases every year. It is known that the reduced supply of oxygen (O₂) induced by acute or chronic increases in altitude stimulates the body to adapt to new metabolic challenges imposed by hypoxia. Sleep can suffer partial fragmentation because of the exposure to high altitudes, and these changes have been described as one of the responsible factors for the many consequences at high altitudes. We conducted a review of the literature during the period from 1987 to 2012. This work explored the relationships among inflammation, hypoxia and sleep in the period of adaptation and examined a novel mechanism that might explain the harmful effects of altitude on sleep, involving increased Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) production from several tissues and cells, such as leukocytes and cells from skeletal muscle and brain.

Competitive sports and the heart: benefit or risk?

BACKGROUND

Controversy surrounds the cardiac effects of competitive sports and the athlete's heart. In this review, we present and discuss the main cardiological findings in competitive athletes.

METHOD

Selective review of pertinent literature retrieved by a search with the keywords "athlete's heart," "ECG," "echocardiography," "endurance exercise," "longevity," and others.

RESULTS

Regular exercise leads to functional and structural adaptations that improve cardiac function. Athlete's heart, which develops rarely, is a typical finding in endurance athletes. This condition is characterized by physiological, harmonically eccentric hypertrophy of all cardiac chambers. The athlete's ECG can be used to distinguish physiological, training-related changes from pathological training-unrelated changes. The athlete's heart function is normal at rest and increases appropriately during exercise. The cardiac markers troponin and B-type natriuretic peptide are within the normal range in healthy athletes at rest, but can temporarily be mildly elevated after exhausting endurance-exercise, without evidence of myocardial damage. The epidemiological data suggest that participation in competitive sports increases life expectancy.

CONCLUSION

Competitive exercise does not induce cardiac damage in individuals with healthy hearts, but does induce physiological functional and structural cardiac adaptations which have positive effects on life expectancy.

The impact of obesity on cardiac troponin levels after prolonged exercise in humans

Elevated cardiac troponin I (cTnI), a marker for cardiac damage, has been reported after high-intensity exercise in healthy subjects. Currently, little is known about the impact of prolonged moderate-intensity exercise on cTnI release, but also the impact of obesity on this response. 97 volunteers (55 men and 42 women), stratified for BMI, performed a single bout of walking exercise (30-50 km). We examined cTnI-levels before and immediately after the exercise bout in lean (BMI < 25 kg/m(2), n = 30, 57 ± 19 years), overweight (25 ≤ BMI < 30 kg/m(2), n = 29, 56 ± 11 years), and obese subjects (BMI ≥ 30 kg/m(2), n = 28, 53 ± 9 years). Walking was performed at a self-selected pace. cTnI was assessed using a high-sensitive cTnI-assay (Centaur; clinical cut-off value ≥ 0.04 μg/L). We recorded subject characteristics (body weight, blood pressure, presence of cardiovascular risk) and examined exercise intensity by recording heart rate. Mean cTnI-levels increased significantly from 0.010 ± 0.006 to 0.024 ± 0.046 μg/L (P < 0.001). The exercise-induced increase in cTnI was not different between lean, overweight and obese subjects (two-way ANOVA interaction; P = 0.27). In 11 participants, cTnI was elevated above the clinical cut-off value for myocardial infarction. Logistic regression analysis identified exercise intensity (P < 0.001), but not BMI, body fat percentage or waist circumference to significantly relate to positive troponin tests. In conclusion, prolonged, moderate-intensity exercise results in a comparable increase in cTnI-levels in lean, overweight and obese subjects. Therefore, measures of obesity unlikely relate to the magnitude of the post-exercise elevation in cTnI.

Diagnostic and Prognostic Information Provided by a High Sensitivity Assay for Cardiac Troponin T

Cardiac troponins (cTns) are the preferred biomarkers for the diagnosis of acute myocardial infarction, assessment of risk and prognosis, and for determination of antithrombotic and revascularization strategy in patients with acute coronary syndromes. The implementation of high sensitivity cTn assays into the clinical routine has increased the number of patients diagnosed with myocardial infarction. In addition, the number of patients with elevated cTn levels that cannot be explained by acute ischemic injury was increased, which is observed in patients with chronic heart disease and other nonischemic cardiac injury or in patients with impaired renal function. The new definition of myocardial infarction provides support for the interpretation of elevated cTn measured with high sensitivity cTn assays in patients with suspected acute coronary syndrome. This review will summarize clinical studies with the recently introduced high sensitivity cTnT assay (TnT hs) with reference to recent experience with high sensitivity cTn assays in general.

Effect of prolonged walking on cardiac troponin levels

Increased cardiac troponin I (cTnI), a marker for cardiac damage, has been reported after strenuous exercise in young subjects. However, little is known about changes in cTnI after moderate-intensity exercise in a heterogenous population or which factors may contribute to this change in cTnI levels. We examined cTnI levels before and immediately after each day of a 4-day long-distance walking event (30 to 50 km/day) in a heterogenous group (67 men, 42 women), across a broad age range (21 to 82 years), with known cardiovascular pathology or risk factors present in many subjects (n = 24). Walking was performed at a self-selected pace. Cardiac TnI was assessed using a standard system (Immulite) with high values (>or=0.20 microg/L) cross-checked using a high-sensitive cTnI assay (Centaur). Mean cTnI levels increased significantly from 0.04 to 0.07 microg/L on day 1, with no further increase thereafter (p <0.001, analysis of variance). Backward linear regression found a weak, but significant, association of age (p <0.001), walking speed (p = 0.02), and cardiovascular pathology (p = 0.03) with postexercise cTnI level (combined r(2) = 0.11, p <0.001). In 6 participants (6%), cTnI was increased above the clinical cut-off value for myocardial infarction on >or=1 day. These participants supported the regression analysis, because they were older, walked at higher relative exercise intensity, and reported a high prevalence of cardiovascular pathology. In conclusion, prolonged, moderate-intensity exercise may result in an increase in cTnI levels in a broad spectrum of subjects, especially in older subjects with pre-existing cardiovascular disease or risk factors.

Pulmonary oedema and hyponatraemia after an ironman triathlon

A 36-year-old man presented with symptoms of acute pulmonary oedema at the conclusion of the Australian ironman triathlon. He was alert, orientated, with an oxygen saturation of 75% on room air. Chest examination revealed bilateral basal crepitations. Serum sodium was 120 mmol/L and chest x ray revealed bilateral basal opacities. He was treated for acute pulmonary oedema with prompt improvement and given 200 ml of intravenous hypertonic saline followed by normal saline. Serum sodium decreased to 117 mmol/L and 30 hours after presentation he had a seizure. He fully recovered and was discharged 5 days after admission. This case highlights that exercise-associated hyponatraemia and pulmonary oedema are still not widely understood and there is still a reluctance to treat hyponatraemia aggressively with ongoing hypertonic saline.

Reference population and marathon runner sera assessed by highly sensitive cardiac troponin T and commercial cardiac troponin T and I assays

BACKGROUND

Endurance exercise can increase cardiac troponin (cTn) concentrations as high as those seen in cases of minor myocardial infarction. The inability of most cTn assays to reliably quantify cTn at very low concentrations complicates a thorough data analysis, and the clinical implications of such increases remain unclear. The application of recently developed highly sensitive cTn immunoassays may help resolve these problems.

METHODS

We evaluated the precommercial highly sensitive cardiac troponin T (hs-cTnT) assay from Roche Diagnostics and the Architect cardiac troponin I (cTnI-Architect) assay from Abbott Diagnostics by testing samples from a reference population of 546 individuals and a cohort of 85 marathon runners. We also measured the samples with the current commercial cTnT assay for comparison.

RESULTS

Although the hs-cTnT and cTnI-Architect assays were capable of measuring cTn concentrations at low concentrations (<0.01 microg/L), only the hs-cTnT assay demonstrated a CV of <10% at the 99th percentile of the reference population and a near-gaussian distribution of the measurements. After a marathon, 86% of the runners had cTnT concentrations greater than the 99th percentile with the hs-cTnT assay, whereas only 45% of the runners showed increased concentrations with the current cTnT assay. cTn concentrations remained significantly increased the day after the marathon. A multiple regression analysis demonstrated marathon experience and age to be significant predictors of postmarathon cTn concentrations (P < 0.05).

CONCLUSIONS

The hs-cTnT assay was the only assay tested with a performance capability sufficient to detect cTn concentrations in healthy individuals. The number of runners with increased cTn concentrations after a marathon depends highly on an assay's limit of detection (LOD). The assay with the lowest LOD, the hs-cTnT assay, showed that almost all runners had increased cTn concentrations. The clinical implications of these findings require further investigation.

Exercise-induced cardiac troponin T release: a meta-analysis

PURPOSE

Cardiac troponin T (cTnT) is a highly specific marker of myocardial damage and used clinically in the diagnosis of acute myocardial infarction (AMI). Release of cTnT has been demonstrated in several small studies after endurance exercise. The purpose of this study was to explore, using a meta-analytic approach, the incidence of postexercise cTnT release after endurance exercise.

METHODS

Articles identified via Pubmed, SportDiscus, and Embase (1997-2006) searches using the key words cardiac troponin T, cTnT, cardiac biomarkers, and exercise; a search of bibliographies; and consultation with experts in the field were entered into a random-effects meta-analysis. We identified 26 relevant studies (1120 cases). Age, gender, and body mass of participants, as well as exercise mode and duration, were explored as possible moderator variables with meta-regressions.

RESULTS

Postexercise cTnT levels exceeded the assay detection limit in 47% of participants (95% CI = 39-56%). The detection of postexercise cTnT after cycling events was approximately half that of running events (27 vs 52%, P = 0.042). The detection of postexercise cTnT decreased slightly as event duration increased (P = 0.022) and mean body mass decreased (P = 0.0033). Postexercise detection of cTnT was not affected by age (P= 0.309) and was only slightly higher for studies with more males in the sample (P = 0.028).

CONCLUSIONS

Exercise-induced cTnT release is apparent in almost half of the endurance athletes who have been studied to date. Relatively heavy individuals competing in shorter endurance events, primarily running marathons, are slightly more likely to demonstrate elevated cTnT postexercise than other athletes. These data are useful for clinicians evaluating athletes with cTnT elevations after competitive endurance exercise events.

Serum cardiac troponin T, troponin I, plasma BNP and left ventricular mass index in professional football players

Concentrations of cardiac troponins (cTn) in serum or plasma may be elevated in several disease states other than acute coronary syndromes. In heart failure and end stage renal disease, cardiac troponin T (cTnT) correlates positively with left ventricular mass index (LVMI). Exercise-induced elevation of cardiac troponins in well-trained athletes has been confirmed by several reports but the aetiology and clinical significance is unclear. In the present study, we measured baseline concentrations of cardiac markers and investigated whether or not serum cTnT is associated with left ventricular hypertrophy (LVH) in professional football players.

METHODS

Twenty-three male professional football players with a mean age of 23 years (range 18-32) were studied. Echocardiography and blood sampling were carried out approx 24h after a training session. Serum cTnT, other cardiac markers and plasma brain natriuretic peptide (BNP) were compared with LVMI.

RESULTS

cTnT was only detectable in one subject. The prevalence of elevated cardiac troponin I (cTnI), creatine kinase MB (CKMB) and creatine kinase was higher than for cTnT. cTnI concentrations were higher in football players than in controls. LVMI did not correlate with any of the cardiac markers. Plasma BNP concentrations were normal in all subjects.

CONCLUSION

Serum cTnT concentrations were not elevated in healthy professional football players with LVH. This argues against the hypothesis that LVH per se may cause increased cTnT. The finding of higher cTnI in football players than in non-athletic controls should be confirmed and the aetiology elucidated.

Serum chemistry alterations in Alaskan sled dogs during five successive days of prolonged endurance exercise

OBJECTIVE

To determine the impact of successive days of endurance exercise on select serum chemistry values in conditioned Alaskan sled dogs.

DESIGN

Prospective cohort study.

ANIMALS

10 conditioned Alaskan sled dogs.

PROCEDURES

All dogs ran 160 km/d for 5 consecutive days. Serum was obtained prior to exercise and immediately after each exercise run; all samples were obtained before dogs were fed. Serum electrolyte, mineral, protein, total bilirubin, urea nitrogen, creatinine, and cardiac troponin-I concentrations and serum alkaline phosphatase, alanine aminotransferase, creatine kinase, and aspartate aminotransferase activities were measured. Data were analyzed by means of analysis of covariance for a randomized complete block design with dog as a blocking variable, time as a covariate, and distance run as the treatment of interest. Least square mean values were compared with values obtained prior to exercise, and linear and quadratic contrasts were examined.

RESULTS

Serum globulin concentration was low prior to exercise (mean +/- SD, 2.2 +/- 0.3g/dL) and progressively decreased as exercise continued. Exercise was associated with increases in serum chloride, urea nitrogen, and cardiac troponin-I concentrations and serum alanine aminotransferase, creatine kinase, and aspartate aminotransferase activities and with progressive decreases in serum potassium, total protein, and albumin concentrations.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that multiple successive days of endurance exercise resulted in mild aberrations in serum chemistry variables in conditioned sled dogs. Changes likely reflected the metabolic stresses of prolonged endurance exercise as well as dietary composition. Hypoglobulinemia in resting, conditioned sled dogs may reflect the immunosuppressive or catabolic effects of intense endurance training.

Novel application of flow propagation velocity and ischaemia-modified albumin in analysis of postexercise cardiac function in man

The present study employed novel echocardiographic tools and cardiac markers to obtain a greater understanding of the aetiology and time course of altered cardiac function and cardiac damage following prolonged exercise and, in particular, the possible role of transient ischaemia within these phenomena. Fourteen runners in the 2004 London Marathon were assessed pre-, immediately post-, 1 h post- and 24 h postcompletion of the race. Left ventricular function was examined echocardiographically using 2-D, M-mode, tissue Doppler imaging and flow propagation velocity (Vp). Venous blood samples were analysed for N-terminal pro-B-type natriuretic peptide (proBNP), cardiac troponin T (cTnT) and ischaemia-modified albumin (IMA). Left ventricular (LV) diastolic filling was altered on completion of the race, as indicated by significant decreases in mean early to late diastolic myocardial wave (E':A') ratio and Vp (from 1.82 +/- 0.9 to 1.32 +/- 0.32, and from 67.5 +/- 9.3 to 60.2 +/- 8.2 cm s(-1), respectively, P < 0.05), accompanied by an increase in proBNP (from 21.6 +/- 11 to 47.08 +/- 19.5 pg l(-1), P < 0.05). The observed reduction in LV diastolic filling following completion of a marathon, unrelated to changes in heart rate or loading parameters, indicates an intrinsically mediated change in diastolic filling. Exercise-induced elevations in cTnT in nine individuals (range, 0.023-0.37 microg l(-1)) were indicative of minor cardiac damage. A significant reduction in IMA was observed after the marathon (from 63.68 +/- 9.83 to 44.94 +/- 16.13 Um l(-1), P < 0.05), unrelated to the alterations in cardiac function, proBNP or cTnT. The absence of an elevation in IMA suggests that exercise-induced myocardial ischaemia did not occur and therefore could not explain the changes in cardiac function or biomarkers. Future studies in this area should investigate alternative diagnostic tools for the detection of transient ischaemia, and other potential mechanisms, in order to extend the understanding of this phenomenon.

Cardiac drift during prolonged exercise with echocardiographic evidence of reduced diastolic function of the heart

This study examined whether, in 16 male subjects, a continuous increase in heart rate (HR) during 4 h of ergometry cycling relates to cardiac fatigue or cardiomyocyte damage. Serum cardiac troponin T (cTnT) was determined and echocardiographic assessment was carried out prior to and after 2 h of exercise, within 15 min of completing exercise and after 24 h. Left ventricular contractile function (end-systolic blood pressure-volume relationship [SBP/ESV]) and diastolic filling (ratio of early to late peak left ventricular filling velocities [E:A]) were calculated. During exercise HR was 132+/-5 beats min(-1) after 2 h and increased to 141+/-5 beats min(-1) (mean +/- SD; P<0.05), but there was no evidence of altered LV contractile function (SBP/ESV 39.0+/-5.1 mmHg cm(-1) to 36.5+/-5.2 mmHg cm(-1) and SBP/ESV was not correlated to maximal oxygen uptake (r(2)=0.363). In contrast, E:A decreased (1.82+/-0.32 to 1.48+/-0.30; P<0.05) and returned towards baseline after 24 h (1.78+/-0.28), and individual changes were correlated to maximal oxygen uptake (r(2)=0.61; P<0.05). Low levels of cTnT were detected in two subjects after 4 h of exercise that had normalised by 24 h of recovery. During prolonged exercise cardiovascular drift occurred with echocardiographic signs of a reduced diastolic function of the heart, especially in those subjects with a high maximal oxygen uptake.

Postexercise Left Ventricular Function and cTnT in Recreational Marathon Runners

PURPOSE

To assess the impact of prolonged exercise on left ventricular (LV) function and the appearance of cardiac troponin T (cTnT) in older and recreational athletes.

METHODS

Heart rate (HR), blood pressures, and cTnT were recorded in 35 subjects (age range 22-57 yr, finishing time 157-341 min) pre- and postrace. Echocardiograms (N = 26) assessed stroke volume (SV), ejection fraction (EF), sBP/LV end-systolic volume (sBP/ESV), diastolic filling (E:A ratio) as well as preload (LV internal dimension at end-diastole [LVIDd]) and afterload (LV wall stress). HR and core temperature were recorded in-event. Prepost changes in LV function were analyzed by repeated measures t-test. Delta scores for LV function and cTnT data were correlated with each other, age, finishing time, alterations in loading, and in-event data.

RESULTS

SV was significantly decreased postrace (109 +/- 31 vs 85 +/- 25 mL, P < 0.05) likely due to a significant decrease in LVIDd (5.3 +/- 0.4 vs 4.9 +/- 0.5 cm, P < 0.05; r = 0.80, P < 0.05). LV wall stress was unchanged postrace (90 +/- 25 vs 89 +/- 27 g x cm(-2), P > 0.05). EF (70 +/- 12 vs.70 +/- 10%, P > 0.05) and sBP/ESV (3.7 +/- 2.9 vs 4.0 +/- 2.0, P > 0.05) did not change prepost race and were not related to age or finishing time (P > 0.05). E:A ratio was significantly reduced postrace (1.73 +/- 0.38 vs 1.41 +/- 0.25, P < 0.05) and could not be explained by an increased HR (56 +/- 9 vs 84 +/- 10, P < 0.05; r = 0.08, P > 0.05), a reduced LVIDd (r = 0.11, P > 0.05), age, finishing time, or in-event data. Postrace 26/33 subjects presented cTnT values in the range 0.024-0.080 microg x L(-1) that were not related to changes in LV function, loading, age, finishing time, or in-event data.

CONCLUSION

No evidence of load-independent depression in LV systolic function was reported. Changes in cTnT and E:A were not related, and their etiology is uncertain.

Clinical significance of increased cardiac troponins T and I in participants of ultra-endurance events

Of 105 asymptomatic finishers of endurance competitive events lasting several hours, increased blood concentrations of cardiac troponins T and I above the 99% upper reference values were found in 24 and 34 subjects, respectively; N-terminal pro-brain natriuretic peptide was also significantly increased. Within 3 months after the events, 21 troponin-positive participants underwent an extensive cardiac examination, which in all but 1 (critical coronary heart disease) revealed no signs of persistent cardiac damage.

Comparison of cardiac troponin T and I in healthy men and in aortic valve replacement

Troponins are of outstanding importance for the diagnosis of myocardial infarction. Cardiac troponin T (cTnT) and the various cardiac troponin I (cTnI) assays differ with respect to method comparison, diagnostic sensitivity and diagnostic specificity. To understand the differences in the diagnostic behavior of troponin assays, AccuTnI and Elecsys Troponin STAT were used in a group of healthy men and in the follow-up of patients with aortic valve replacement (AVR). Within the healthy subjects AccuTnI was able to differentiate two subgroups from each other, whereas the cTnT concentrations of all subjects were below the detection limit. In AVR patients, cTnT and cTnI correlated sufficiently, if the postoperative periods were taken into consideration. There was a rapid increase in cTnI within 24 h. In contrast, a broad peak was evident for cTnT between 48 and 120 h. The results emphasize more the differences in the release of cTnI and cTnT from the cytoplasm and the thin filaments of the cardiomyocytes than the modifications of the troponins circulating in the blood.