Immune checkpoint inhibitor-associated myocarditis is a rare but highly fatal complication. Cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are central to diagnosis and prognostic assessment, yet their clinical differences remain poorly defined. This review compares the biological characteristics, analytical factors, and clinical interpretation of cTnT and cTnI in ICI-associated myocarditis. Available evidence suggests that cTnT is more frequently elevated and has a stronger evidence base for surveillance, whereas cTnI provides complementary information for myocardial source attribution, particularly when skeletal muscle involvement or other confounding factors are present. However, neither biomarker alone can confirm or exclude ICI-associated myocarditis. Appropriate interpretation requires integration of troponin trajectories, clinical presentation, electrocardiography, imaging findings, and evaluation of potential non-cardiac causes.

Chagas disease is a parasitic infection that is endemic to Latin America and primarily transmitted by insects. When untreated, Chagas disease can cause cardiomyopathy. Serological testing capacities for Chagas disease are limited, but Chagas cardiomyopathy often manifests in electrocardiograms (ECGs), providing an opportunity to use ECG-based screening to prioritize patients for testing and treatment.

Approach: The George B. Moody PhysioNet Challenge 2025 invited teams to develop algorithmic approaches for identifying potential cases of Chagas disease from ECGs. The Challenge metric, denoted by TPR@5%, measured the true positive rate of the top 5% of patients determined by an algorithm to be the most likely to have Chagas disease, reflecting the Brazilian serological testing capacity. The data included more than 360,000 ECGs from five Brazilian databases. We also developed an ensemble algorithm for the best-performing entries.

Main results: This Challenge provided multiple innovations. First, we leveraged several datasets with labels from either patient reports or serological testing, providing a large dataset with weak labels and smaller datasets with strong labels. Second, we augmented the data to support model robustness and generalizability to unseen data sources. Third, we applied an evaluation metric, TPR@5%, that captured the local serological testing capacity for Chagas disease to frame the Challenge as a triage task. Fourth, we developed an ensemble model that combined the individual Challenge models to improve performance. These innovations provided reliable sensitivity at clinically relevant operating points. The performance of the top-performing Challenge model (Biomed-Cardio) varied performed well across datasets (TPR@5% of 0.468 on REDS-II and TPR@5% of 0.125 on ELSA-Brasil), and our ensemble-based approach demonstrated consistent performance across datasets (TPR@5% of 0.389 on REDS-II and TPR@5% of 0.146 on ELSA-Brasil).

Significance:
Over 630 participants from 111 teams submitted over 1300 entries during the Challenge, representing diverse approaches from academia and industry worldwide.

Coronary artery aneurysm is a rare condition commonly treated with conventional surgery under cardiopulmonary bypass because of its complexity. Here, we present a patient who underwent minimally invasive off-pump coronary surgery via left mini-thoracotomy for a left anterior descending artery saccular aneurysm. A Japanese woman in her late 40s, who had been treated with beta-blocker therapy for hypertrophic cardiomyopathy, and steroid and immunosuppressive therapies after renal transplantation, developed chest discomfort on effort recently. Digital Holter electrocardiography showed ST-segment depression associated with exertional dyspnea, suggesting ischemic heart disease. Coronary angiography revealed a saccular aneurysm of the left anterior descending artery that had caused ischemia due to turbulence. This patient was diagnosed with a left coronary artery aneurysm causing ischemic symptoms, which indicated surgical intervention, whereas we judged that the mild to moderate mitral valve regurgitation and mild left ventricular outflow stenosis, caused by hypertrophic cardiomyopathy, did not require surgical interventions. Then, we performed aneurysmal plication after bypass grafting to the left anterior descending by the left internal thoracic artery via left mini-thoracotomy under off-pump guidance. The patient recovered well, and the symptoms disappeared. Postoperative computed tomography angiography showed good patency of the internal thoracic artery and complete disappearance of the aneurysm. This case demonstrates the potential utility of minimally invasive off-pump coronary surgery via left mini-thoracotomy as a useful alternative for patients with simple left coronary artery aneurysms.

Carbetocin is an oxytocin receptor agonist used for postpartum hemorrhage prevention. While oxytocin is known to transiently prolong the QT/QTc interval, robust QTc data for carbetocin are limited. Carbetocin is known to elevate HR, which can impact QTc analyses; thus, a dose that did not overly elevate HR was important to select. This randomized, placebo- and positive-controlled trial evaluated the effect of a single intravenous infusion of a supratherapeutic dose (650 μg) of carbetocin over 45 min on cardiac repolarization in healthy adults (N = 42). Continuous cardiodynamic ECGs were recorded from 45 min before through 24 h after dosing. The primary endpoint was placebo-corrected change from baseline in QT interval (ΔΔQTc) using the most appropriate heart rate (HR) correction method. The primary analysis was based on exposure-response modeling of the relationship between carbetocin plasma concentrations and ΔΔQTc, to identify an effect ≥ 10 msec at the high clinical exposure. During intravenous infusion of carbetocin, the mean HR change from baseline reached a maximum of 16.7 bpm. Multiple correction methods for HR were assessed, and the placebo-corrected, optimized, individualized heart rate-corrected QT interval (oQTcI) was found to be adequate. The estimated mean placebo-corrected oQTcI change from baseline was 4.5 msec (90% CI: 3.4, 5.6) at the high clinical exposure level of 12.4 ng/mL following a single intravenous infusion of 867 μg/h carbetocin. Exposure-response models for carbetocin established no predicted QTc prolongations of clinical or regulatory concern (≥ 10 msec) at the high clinical exposure level. Trial Registration: ClinicalTrials.gov Registration: NCT05924321.

A 7-year, 6-month-old, female neutered, Pug dog presented with lethargy, hyporexia, polydipsia, abdominal distension, and dyspnea. Point-of-care ultrasonography identified tricavitary effusions and cardiac tamponade. Pericardiocentesis yielded 83 mL of sanguineous scintillating fluid. Clinical examination, bloodwork, echocardiography, electrocardiography, thoracic and abdominal computed tomography scans, and pericardial fluid analysis including culture and sensitivity did not identify any cardiovascular, endocrine, neoplastic, or infectious causes of the pericardial effusion. Pericardial fluid analysis identified high cholesterol concentrations and numerous cholesterol crystals on cytology, supporting a diagnosis of cholesterol pericarditis. Subtotal pericardiectomy was performed 7 weeks later to address pericardial and pleural effusions. Histopathological pericardial biopsies identified pericarditis with no neoplastic tissue detected. A pleural port was placed 4 months later to manage recurrent pleural effusion. Elective euthanasia was performed 10 weeks later citing a compromised quality of life from increasingly frequent bouts of dyspnea. This is a case report of a dog with idiopathic cholesterol pericarditis presenting with cardiac tamponade.

The assessment of cardiorespiratory adaptation during exercise is not only crucial for studying physiological adaptation to physical training, but also essential for preclinical research, as measurements at rest can mask underlying physiological phenomena. However, conventional preclinical methods, such as surgically implanted telemetry or hermetic chambers, come with important constraints. To overcome these limitations, we present a surgery-free methodology using a jacketed telemetry system, enabling the simultaneous monitoring of heart rate (HR), respiratory rate (RespR), and locomotor activity (AL) in rats during forced treadmill exercise. The protocol implements a two-phase acclimatization process designed to ensure both the appropriate running performance of the animals and data integrity: first, habituation to wearing the telemetry jacket, which integrates respiratory inductive plethysmography sensors and surface electrocardiogram electrodes; and second, a 2-week (five days per week) habituation to treadmill exercise. We detail equipment procedures and essential quality control steps, including real-time signal verification, to minimize animal stress and ensure reliable, low-noise physiological data. We also provide representative signal examples to help users achieve high data quality, especially during exercise protocols, but also in other experimental contexts. When implemented correctly, this protocol enables consistent monitoring at speeds up to 40 cm.s[-][1], allowing the quantification of changes in HR, RespR, and AL compared to baseline. By eliminating the need for surgical interventions, this protocol strongly adheres to the ethical principles of the 3Rs (reduce, refine, replace). While the provided techniques focus on exercise, they have potential applications across diverse fields, including comprehensive cardiorespiratory characterization, animal handling training, welfare monitoring, and physiology, pharmacology, or education.

Vagal-mediated cardiovascular responses can occur following carbon dioxide pneumoperitoneum during laparoscopic surgery. In rare cases, an exaggerated vagal reflex may result in profound bradycardia or asystole. We report the case of a 44-year-old woman (American Society of Anesthesiologists physical status II) who developed abrupt bradycardia progressing to asystolic cardiac arrest immediately after abdominal insufflation during an elective minimally invasive gynecologic procedure. The planned operation included hysteroscopy with MyoSure (Hologic, Inc., Marlborough, MA, US) resection, NovaSure (Hologic) endometrial ablation, Acessa (Hologic) radiofrequency fibroid ablation, diagnostic laparoscopy, and salpingectomy for symptomatic uterine fibroids refractory to conservative management. Her past medical history was notable only for uterine fibroids and recently diagnosed hypertension. Preoperative laboratory testing and vital signs were within normal limits, and electrocardiography demonstrated normal sinus rhythm without clinically significant rhythm abnormalities. Immediately following the bradycardia, one milligram of atropine was administered intravenously. The patient then became asystolic, pneumoperitoneum was evacuated, and cardiopulmonary resuscitation was initiated. Return of spontaneous circulation was achieved after a single round of compressions, with restoration of normal sinus rhythm. The intra-abdominal portion of the procedure was subsequently aborted, and the patient remained hemodynamically stable postoperatively. At cardiology follow-up nine days postoperatively, the patient reported prior vasovagal-type episodes, including syncope following influenza vaccination and near-syncope during magnetic resonance imaging with intravenous contrast. This case highlights the importance of rapid recognition and management of vagally mediated cardiac events in the operating room. It also raises the question of whether targeted preoperative assessment for prior syncope or vasovagal episodes may help identify patients at increased risk for exaggerated vagal responses during procedures involving pneumoperitoneum, a potential area for future investigation.

The South African flag sign (SAFS) is a non-contiguous electrocardiographic pattern defined by ST-segment elevation (STE) in leads I, aVL, and V2 with reciprocal inferior ST-segment depression (STD), classically associated with first diagonal branch (D1) occlusion. We report a 58-year-old female presenting with acute chest pain and atrial fibrillation (AF), whose 12-lead electrocardiogram (ECG) demonstrated a SAFS phenotype. Automated ECG interpretation generated no ST-segment elevation myocardial infarction (STEMI)-specific alert, classifying the tracing as AF with possible subendocardial injury. This failure may have resulted from AF-induced RR variability combined with non-contiguous STE distribution outside standard algorithmic thresholds. Visual pattern recognition prompted STEMI pathway activation before hospital arrival. Coronary angiography confirmed acute thrombotic total occlusion of the proximal left anterior descending artery (LAD) with Thrombolysis in Myocardial Infarction (TIMI) 0 flow. Primary percutaneous coronary intervention restored TIMI 3 flow. The hospital course was complicated by severe left ventricular dysfunction, acute heart failure, and extensive microvascular obstruction. This case confirms SAFS as a rare but clinically meaningful phenotype and provides new diagnostic and angiographic insight by associating it with isolated proximal LAD occlusion, AF, and failed automated STEMI recognition. It suggests SAFS is not restricted to D1 occlusion, and visual ECG interpretation remains essential when automated systems fail.

To investigate the effect of R-R interval (RRI) normalization using different scaling factors ([Formula: see text]) on frequency-domain heart rate variability (HRV) parameters during sleep, and determine whether normalization improves the differentiation of sleep stages and enhances the accuracy of slow-wave sleep (SWS) detection. We analyzed the overnight electrocardiogram data of 130 participants. RRIs were normalized using a proposed z-score method with scaling factors (n = 1-4 in [Formula: see text]). Frequency-domain HRV parameters were extracted using raw and normalized RRIs within a 5-min time window shifted by 30 s. HRV parameters were statistically compared across sleep stages (wakefulness, light sleep, SWS, and rapid eye movement sleep), and the SWS detection performance was evaluated using receiver operating characteristic analysis. RRI normalization significantly magnified differences in HRV parameters across sleep stages. HF, which reflects parasympathetic activity, showed a markedly clearer separation between SWS and other stages with normalization (p < 0.05) than with the raw RRI. Consequently, the SWS detection performance was significantly improved. The area under the curve for HF-based SWS detection increased from 0.50 (raw RRI) to a maximum of 0.86 (with [Formula: see text] normalization). HRV parameters derived from normalized RRI reveal the hierarchical organization of autonomic nervous activity across sleep stages, particularly parasympathetic dominance in SWS. This method significantly improves SWS detection accuracy and provides a robust foundation for refined HRV-based sleep monitoring systems. It can be utilized in real-time health monitoring systems to accurately assess sleep stages, stress, and fatigue levels.