Myocardial Injury and the Release of Troponins I and T in the Blood of Patients

Background Cardiac troponin I (cTnI) and cTnT are the established biomarkers of cardiomyocyte damage and the recommended biomarkers for the diagnosis of acute myocardial infarction (MI). High-sensitivity immunochemical diagnostic systems are able to measure the cTn concentrations in the blood of a majority of healthy people. At the same time, the concentration of cTn may be increased not only after MI but also because of other pathologies that might affect myocardium. This effect reduces the clinical specificity of cTn for MI and may complicate the diagnosis. Content This review summarizes the existing information regarding the causes and mechanisms that lead to the increase of cTn concentration in blood and the forms of cTn that are present in circulation after MI or other types of myocardial injury. Summary Different etiologies of disease associated with increases of cTn above the 99th percentile and various mechanisms of troponin release from myocardium could result in the appearance of different forms of cTn in blood and provide the first clinical evidence of injury. Additional research is needed for the careful characterization of cTn forms that are present in the blood in different clinical settings. That knowledge may lead to the development of immunochemical systems that would differentiate certain forms of troponins and possibly certain types of cardiac disease.

Troponin-I release after cardiac surgery with different surgical techniques and post-operative neurological outcomes

Cerebral hypoperfusion during cardiopulmonary bypass surgery has been thought to be a factor in the aetiology of brain damage with evidence of post operative neurological deficits. Cardiacspecific biomarkers such as troponin-I, troponin-T and CK-MB have been used extensively to predict myocardial injury and ischaemia. This prospective study investigateed the level of troponin-I release in both off-pump and CPB-technique CABG surgery, as well as postulated a relationship of troponin release and post-operative neurological outcome. A total of 44 adult patients undergoing coronary artery bypass graft (CABG) were enrolled into either an off-pump or on-pump groups, with 22 patients participating in each. Group A (on-pump) underwent myocardial revascularisation with CPB and cardioplegic arrest, while Group B (off pump) underwent beating heart surgery. The measurement of troponin-I is a 1-step enzyme immunoassay method, with specificity and sensitivity set at 0.4 ug/mL. Neurological assessment was done using the NIH Stroke Scale, and neuropsychologic assessment was assessed on cognitive function using modified Weschler Memory Scale, for which scores were standardized to achieve a composite measure of concentration. A set of statistical analysis was done to correlate troponin-I release with different surgical techniques of CPB and OPCAB. Although each independent technique showed a marked rise of troponin-I from baseline to 6 hours post-operatively, the difference in troponin release was not significant between the 2 groups at specified time intervals (p=0.124). There was however a significant correlation of troponin-I release with the number of grafts used in the surgery, irrespective of the type of grafts or surgical technique. None of the patients in either group showed any neurological or cognitive deficits presenting at day 3 and day 7 post-operatively. The findings of this study demonstrate that there is no significant short-term cognitive or neurological dysfunctions post operatively, as indicated by troponin-I release in assessing the severity of myocardial injury.

Baseline features and management in adult and pediatric clinically suspected and biopsy-proven myocarditis in the cardiomyopathy and myocarditis long-term EORP registry

Background The Myocarditis section of the EORP Cardiomyopathy and Myocarditis Long-term Registry is a prospective, observational, multinational registry of adult and pediatric patients enrolled using the ESC 2013 diagnostic criteria of clinically suspected (CS) or biopsy-proven (BP) myocarditis (myoc). Purpose i) To obtain a real-world snapshot of features and management of myoc; ii) to assess features at presentation in CS and in BP myoc and by age. Methods 581 patients (68% male), 493 adults, aged 34.9 (SD 18.5) years, and 88 children, aged 8.1 (SD 5.2) years, were divided into 3 groups (G): G1 (n=234, 40%), CS myoc plus cardiac magnetic resonance (CMR) confirmed; G2 (n=222, 38,2%), BP myoc; G3 (n=125, 21.5%), CS myoc, no or normal or inconclusive CMR. Baseline features, procedures, medications were analysed in the total population, in adults vs children, and among G. Results In all patients: pseudo-infarct presentation with normal coronary arteries is common (58%), as is heart failure (HF) with or without chest pain and troponin release (58%), followed by arrhythmia (41.9%). In children new-onset HF is more common than in adults (29/32, 90% vs 90/190, 47%, p=0.001). In both adult and pediatric G2 BP myoc, HF and arrhythmia were more common than in CS myoc. Left and right ventricular (RV) echocardiography and CMR function indexes and troponins were lower, NT-pro BNP was higher in G2 BP myoc vs G1 and G3 CS myoc. On CMR oedema and/or Late Gadolinium Enhancement (LGE) were found in 57.4% of adult and in 31.3% of paediatric G2 BP myoc. Endomyocardial biopsy (EMB) was obtained in a similar proportion in children (31/88, 35.2%) and adults (185/493, 37.5%, p=NS), ventricular assist devices were more commonly implanted in G2 children (8/32, 25%) than in G2 adults (4/190, 2.1%, p=0.001), ICD tended to be less common in G2 children (2/32, 6.3%) than in G2 adults (48/190, 25%, p=0.07). In all patients EMB, mainly RV (75.8%), had a low complication rate (4.7%), similar in adults vs children, with no procedure-related death. Histology findings were: lymphocitic myoc (78.9%), giant cell (10.9%), sarcoid (6.9%), non specific (16%). Viral genome was found in 44% of patients (most common PVB19, 21.7%, HHV6, 9.5%). In all patients HF and antiarrhytmic drugs were more frequently used in G2, antivirals in a patient minority, steroids in 24.7%, immunosuppression (IS) in 22.6%. In children steroids or IS were given regardless of G, in adults mainly to G2 BP myoc patients, in keeping with the ESC 2013 expert reco's. Conclusions EMB is safe in children and adults and is still the diagnostic gold standard, since CMR failed to identify myoc in a high proportion of G2 BP patients. Etiology-directed therapy was used in a minority of G2 cases, and/or regardless of etiology, thus there is room for improved management. G2 BP patients were older, sicker, had worse biventricular function, more medications and ICDs; follow-up may show their worse outcome. Funding Acknowledgement Type of funding source: None

Influence of Physical Activity on the Level of Cardiac Troponins (Literature Review)

It is well known that regular physical activity has a beneficial effect on the cardiovascular system and reduces the risk of heart disease; however, numerous studies have shown an increase in heart troponin levels after exercise, which indicates damage to the myocardium in apparently healthy people. The prevalence of these results in various exercise conditions and population groups, as well as the potential underlying mechanisms and clinical significance of exercise-induced cardiac troponin release, has not yet been fully determined. This review discusses the effect of exercise on cardiac troponin levels and possible mechanisms for increasing these biomarkers.