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The metabolic processes of endo- and exogenous compounds play an important role in diagnosing and treating patients since many metabolites are laboratory biomarkers and/or targets for therapeutic agents. Cardiac troponins are one of the most critical biomarkers to diagnose cardiovascular diseases, including acute myocardial infarction. The study of troponin metabolism is of great interest as it opens up new possibilities for optimizing laboratory diagnostics. This article discusses in detail the key stages of the cardiac troponins metabolism, in particular the mechanisms of release from a healthy myocardium, mechanisms of circulation in the bloodstream, possible mechanisms of troponin penetration into other biological fluids (oral fluid, cerebrospinal fluid, pericardial and amniotic fluids), mechanisms of elimination of cardiac troponins from the blood, and daily changes in the levels of troponins in the blood. Considering these aspects of cardiac troponin metabolism, attention is focused on the potential value for clinical practice.

Abstract Background The CARdiac MARker Guideline Uptake in Europe (CAMARGUE) program is a multi-country audit of the use of cardiac biomarkers in routine clinical practice. Methods An email link to a web-based questionnaire of 30 multiple-choice questions was distributed via the professional societies in Europe. Results 374 questionnaires were returned from 39 countries, the majority of which were in northern Europe with a response rate of 8.2%–42.0%. The majority of the respondents were from hospitals with proportionately more responses from central hospitals than district hospitals. Cardiac troponin was the preferred cardiac biomarker, evenly split between cardiac troponin T (cTnT) and cardiac troponin I (cTnI). Aspartate transaminase and lactate dehydrogenase are no longer offered as cardiac biomarkers. Creatine kinase, creatine kinase MB isoenzyme, and myoglobin continue to be offered as part of the cardiac biomarker profile in approximately on 50% of respondents. There is widespread utilization of high sensitivity (hs) troponin assays. The majority of cTnT users measure hs-cTnT. 29.5% of laboratories measure cTnI by a non-hs method but there has been substantial conversion to hs-cTnI. The majority of respondents used ng/L and use the 99th percentile as the upper reference limit (71.9% of respondents). A range of diagnostic protocols are in use. Conclusions There is widespread utilization of hs troponin methods. A significant minority do not use the 99th percentile as recommended and there is, as yet, little uptake of very rapid diagnostic strategies. Education of laboratory professionals and clinicians remains a priority.

Human induced pluripotent stem cell-derived cardiomyocytes (iCMs) provide a powerful platform for investigating cardiac biology. However, structural, metabolic, and electrophysiological immaturity of iCMs limits their capacity to model adult cardiomyocytes. Currently, no universally accepted criteria or protocols for effective iCMs maturation exist. This study aimed to identify practical culture conditions that promote iCMs maturation, thereby generating more physiologically relevant in vitro cardiac models. We evaluated the effects of short- and long-term culture in media supplemented with various stimulatory compounds under 2D conditions, focusing on intracellular content and localization of slow skeletal troponin I (ssTnI) and cardiac troponin I (cTnI) isoforms. Our findings demonstrate that the multicomponent metabolic maturation medium (MM-1) effectively enhances the transition toward a more mature iCM phenotype, as evidenced by increased cTnI expression and formation of cross-striated myofibrils. iCMs cultured in MM-1 more closely resemble adult cardiomyocytes and are compatible with high-resolution single-cell techniques such as electron microscopy and patch-clamp electrophysiology. This work provides a practical and scalable approach for advancing the maturation of iPSC-derived cardiac models, with applications in disease modeling and drug screening.

Abstract Background Sex differences in high-sensitivity cardiac troponin (hs-cTn) concentrations from healthy populations have led to the establishment of sex-specific upper reference limits for hs-cTn assays. This study assessed the performance of sex-specific delta (i.e., changes in concentrations) thresholds for the hs-cTnT assay for ruling in acute myocardial infarction (AMI) in different emergency department (ED) populations. Methods This retrospective study consisted of 2 cohorts (Cohort 1 derivation and Cohort 2 validation). Cohort 1 consisted of 18 056 ED patients who had serial hs-cTnT measured using a 0-h/3-h algorithm at a US medical center, with Cohort 2 consisting of 1137 ED patients with 0-h/3-h sampling at a Canadian medical center. The primary outcome was AMI diagnosis with sex-specific deltas derived based on the Youden index and specificity estimates (i.e., ≥90%) in Cohort 1 and validated in Cohort 2. Results In Cohort 1, 42% of all patients had 0-h hs-cTnT above the sex-specific 99th percentile. Males had higher 0-h hs-cTnT (median 17 ng/L) and absolute deltas (median 2 ng/L) than females (0-h median 11 ng/L, P < 0.0001; deltas median 1 ng/L, P < 0.0001) in non-AMI patients but not in patients with AMI. For ruling in AMI, the sex-specific delta thresholds based on 90% specificity (14 ng/L for males, 11 ng/L for females) performed best and resulted in 91% diagnostic accuracy in both males and females. The sex-specific delta thresholds yielding high specificity estimates were confirmed in the validation data set. Conclusions Sex-specific absolute delta thresholds can be used to rule in AMI and are robust across different study populations.

To investigate the clinical value of high-sensitivity cardiac troponin I (hs-cTnI) in evaluating chemotherapy-related cardiac dysfunction (CTRCD) induced by anthracyclines in postoperative breast cancer patients. A retrospective study was conducted including 180 postoperative breast cancer patients treated at our hospital from August 2021 to August 2024. All patients completed six cycles of the cyclophosphamide-epirubicin-fluorouracil (CEF) regimen. According to the Chinese Society of Clinical Oncology (CSCO) guideline criteria, patients were divided into a cardiotoxicity group (n = 50) and a non-cardiotoxicity group (n = 130). Serum hs-cTnI and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, as well as left ventricular ejection fraction (LVEF) measured by echocardiography, were dynamically monitored before chemotherapy (T ) and after each chemotherapy cycle (T -T ). The predictive value of each marker for CTRCD was evaluated using receiver operating characteristic (ROC) curves. Compared with the non-cardiotoxicity group, the cardiotoxicity group showed significantly higher serum hs-cTnI and NT-proBNP levels from T onward, with progressive increases over chemotherapy cycles (P < 0.01), while LVEF progressively decreased (P < 0.01). ROC analysis indicated that serum hs-cTnI at the third chemotherapy cycle (T ) had an area under the curve (AUC) of 0.957 (95% CI: 0.905-0.988) for predicting CTRCD, with an optimal cutoff value of >1358.5 pg/mL, yielding a sensitivity of 92.00% and specificity of 91.54%. Its predictive performance was significantly superior to that of NT-proBNP at the same time point [AUC = 0.684 (95% CI: 0.590-0.763)]. Serum hs-cTnI is a highly sensitive and specific biomarker for the early and dynamic monitoring of anthracycline-induced cardiotoxicity. The hs-cTnI level at mid-chemotherapy (third cycle) has excellent predictive value for CTRCD, facilitating early identification of high-risk patients and timely clinical intervention.

Ivor Lewis esophagectomy impacts circulatory and cardiac function significantly, often leading to elevated postoperative troponin levels. This study aimed to investigate the effect of low-dose esketamine on postoperative levels of the myocardial injury marker high-sensitivity cardiac troponin T in elderly patients undergoing this procedure. 70 elderly patients scheduled for elective Ivor Lewis esophagectomy were randomly assigned using a random number table to the Control group (Group C, n=35) or the Esketamine group (Group K, n=35). In Group K, in addition to conventional anesthetic drugs, intravenous esketamine 0.25 mg/kg was administered during anesthesia induction, followed by continuous intraoperative infusion at 0.125 mg/kg/h as an adjunct to balanced anesthesia. The Control group received conventional anesthesia induction and maintenance. The primary outcome was hs-cTnT concentration at 24 h postoperatively. In Group K, hs-cTnT concentrations were significantly lower than in the control group at 24h (12.1 ± 3.5 vs 18.7 ± 4.7, P < 0.0001) postoperatively, as well as at 6-12h and 48h postoperatively. Although the incidence of myocardial injury within 2 days postoperatively (11.4% vs 22.9%, P = 0.205) and perioperative severe arrhythmias (2.9% vs 11.4%, P = 0.164) was lower in Group K than in Group C, the differences were not statistically significant. Compared to the control group, Group K indicated more stable hemodynamics. Among postoperative complications, the incidence of dreaming was higher in Group K, with no significant differences in other complications. For postoperative pain, Group K had lower Numerical Rating Scale (NRS) scores at PACU discharge and on postoperative day 1 to day 3. The PACU stay was shorter in Group K. Intraoperative low-dose esketamine effectively reduced hs-cTnT concentrations within 2 days postoperatively in elderly patients undergoing Ivor Lewis esophagectomy, demonstrating a potential beneficial effect in preventing myocardial injury and cardiovascular adverse events.

This study was designed to retrospectively analyze the relationship between the levels of cardiac troponin T (cTnT) and cardiac troponin I (cTnI) and the development of left ventricular diastolic dysfunction (LVDD) in septic patients with diabetes mellitus. Furthermore, the predictive value of cTnT and cTnI in the LVDD development in those patients was investigated. The clinical information of 159 septic patients with diabetes mellitus treated in the intensive care unit of Affiliated Hospital of Chengde Medical University from June 2016 to January 2023 were retrospectively analyzed. These patients were separated into LVDD group (LVFP > 15 mmHg) and non-LVDD group (LVFP ≤ 15 mmHg) based on left ventricular filling pressure (LVFP). The differences in clinical data, echocardiographic parameters, as well as cTnT and cTnI levels between the LVDD and non-LVDD groups were compared. The relationship between the cTnT and cTnI levels and the echocardiographic parameters was studied using Pearson correlation analysis. Logistic regression analysis was conducted to explore the factors that influenced the LVDD development in septic patients with diabetes. Receiver operator characteristic (ROC) curves were created to evaluate the predictive value of cTnT and cTnI levels for the LVDD development in septic patients with diabetes. Totally 159 septic patients with diabetes were included in this study, with 97 patients in the LVDD group and 62 in the non-LVDD group. Compared with the non-LVDD group, patients in the LVDD group had much lower left ventricular (LV) early diastolic peak inflow velocity (E), LV advanced diastolic peak inflow velocity (A), E/A, and early diastolic mitral annular velocity (Em) while significantly higher E/Em. The LVDD group showed much higher levels of cTnI and cTnT than the non-LVDD group (P < 0.05). Significant positive correlation between log10cTnI level and E/Em ratio (r = 0.425, P < 0.001) was revealed by the Pearson correlation analysis. Multivariate analysis showed that E/A, E/Em, cTnI and cTnT were independent risk factors for the LVDD development in septic patients with diabetes (P < 0.05). As for ROC curve results, the area under the curve (AUC) of cTnT to predict the development of LVDD in septic patients with diabetes was 0.849 (95% CI 0.788–0.910, P < 0.001); the AUC of cTnI was 0.742 (95% CI 0.666–0.817, P < 0.001). Both cTnT and cTnI are independent risk factors and have predictive value for the LVDD development in septic patients with diabetes mellitus.

To analyze the prediction value of cardiac troponin I (cTnI), cardiac troponin T (cTnT), and the pediatric Sequential Organ Failure Assessment (p-SOFA) score in children with severe sepsis. 80 children with sepsis [Pediatric Critical Illness Score (PCIS) ≥70] were selected and categorized into severe sepsis group (PCIS score of 71-80, n=52) and non-severe sepsis group (PCIS score >80, n=28) according to the PCIS score, and 50 non-septic children admitted to our hospital during the same period were selected as non-sepsis group. The value of cTnT, cTnI, p-SOFA and their combination in predicting the occurrence of severe sepsis was analyzed. The relationship between the each indicator and poor prognosis of children with severe sepsis was analyzed. The plotted ROC curves revealed that the AUC values for predicting the occurrence of severe sepsis were as follows: cTnT: 0.897 (95% CI: 0.787-0.972), cTnI: 0.881 (95% CI: 0.788-0.975), p-SOFA: 0.795 (95% CI: 0.701-0.890), and their combination: 0.935 (95% CI: 0.883-0.988). Regression analysis showed that cTnT, cTnI, p-SOFA score, CRP and PCT levels were significantly associated with the poor prognosis of children with severe sepsis ( < 0.01). cTnI, cTnT, and p-SOFA are closely related to the inflammatory response in children with severe sepsis, and the combination of the three indicators can effectively assess the severity of sepsis. The elevated levels of cTnI and cTnT and increased p-SOFA score are closely associated with the poor prognosis of children with severe sepsis.

Measurement of cardiac troponin in serum is an essential part of diagnosing myocardial infarction in the emergency department. The guidelines suggest that high-sensitivity techniques should be used for measuring cardiac troponin I (cTnI) or cardiac troponin T (cTnT). The aim of our study was to correlate the values of both troponins, and to ascertain which type of troponin is more in agreement with the diagnosis. The patients were classified into four groups: 43 patients in non-ST-elevation myocardial infarction (NSTEMI), 7 in ST-elevation myocardial infarction (STEMI), 48 in Type 2 myocardial infarction, and 21 in the control group. A significant correlation between cTnI and cTnT was found in the NSTEMI (r = 0.70) and Type 2 (r = 0.75) groups while in the control group there was no association (r = −0.06). The ratios of cTnI and cTnT relative to their cut-off values were lower in Type 2 myocardial infarction compared to NSTEMI. This difference can be attributed to the pathophysiology of these two types of heart conditions. The ratio in the NSTEMI group was higher in female than in male patients (53.3 vs. 24.6 ng/L); the same difference was found for the ratio of cTnT (20.8 vs. 13.1 ng/L). In the same manner, the ratios in the Type 2 group were higher in female than in male patients for cTnI (25.6 vs. 12.7 ng/L) as well as for cTnT (19.0 vs. 6.73 ng/L). These differences could be due to biological differences, but they could also be influenced by other factors contributing to different damage responses.