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Aims: Cardiac troponin levels are elevated in Takotsubo syndrome (TTS) with significant overlap to acute myocardial infarction (MI). Long and intact cardiac troponin T (cTnT) forms are typical for MI. This study sought to assess whether the fragmentation composition of cTnT release in TTS differs from MI., Methods and Results: The concentration of long molecular forms of cTnT (long cTnT) was measured with a novel upconversion luminescence immunoassay and total cTnT with a commercial high-sensitivity cTnT assay in 24 TTS patients and in 84 Type 1 MI patients. The ratio of long to total cTnT (troponin ratio) was determined as a measure of cTnT fragmentation. Troponin ratio was lower in TTS patients [0.13 (0.10-0.20) vs. 0.62 (0.29-0.96), P < 0.001]. In the receiver operating characteristic curve analyses, troponin ratio showed a better predictive power than total cTnT in discriminating TTS and MI patients {area under the curve [AUC] 0.869 [95% confidence interval (CI) 0.789-0.948] vs. 0.766 [95% CI 0.677-0.855], P = 0.047}. When restricting the analysis to patients with total cTnT below 1200 ng/L (maximal value in TTS patients), the respective AUC values for total cTnT and troponin ratio were 0.599 (95% CI 0.465-0.732) and 0.816 (95% CI 0.712-0.921) (P = 0.003). At a cut-off point of 0.12, troponin ratio correctly identified 95% of MI patients and 50% of TTS patients., Conclusion: In contrast to Type 1 MI, only a small fraction of circulating cTnT in TTS exists in intact or long molecular forms. This clear difference in troponin composition could be of diagnostic value when evaluating patients with cTnT elevations and suspicion of TTS., Clinical Trial Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04465591., Competing Interests: Conflict of interest: J.K.E.A.: research grants from the Finnish Foundation for Cardiovascular Research and Clinical Research Fund of Turku University Hospital, Turku, Finland; lectures for Astra Zeneca, Bayer, and Boehringer Ingelheim; and pending patent application WO2023187258 (A1)—ASSAY FOR LONG FORMS OF CARDIAC TROPONIN T; T.P.: lectures for Astra Zeneca; T.H.: lectures for AstraZeneca, Astellas, and GSK and pending patent application WO2023187258 (A1)—ASSAY FOR LONG FORMS OF CARDIAC TROPONIN T; T.V.: pending patent application WO2023187258 (A1)—ASSAY FOR LONG FORMS OF CARDIAC TROPONIN T; T.T., S.S., H.J., M.S.: none declared; A.L.-P.: research grants from the Finnish Society of Clinical Chemistry; H.P.: lectures for Roche; K.T.: research grants from The Finnish Foundation for Cardiovascular Research, The Finnish Medical Foundation, The Finnish Foundation for Alcohol Studies, and the Finnish State Research Funding; S.J.: lectures for Amgen, Boehringer Ingelheim, and BMS Pfizer; S.W.: research grants from the Finnish Society of Clinical Chemistry, the Finnish Foundation for Cardiovascular Research, the Turku University Foundation and the Varsinais-Suomi Regional Fund of the Finnish Cultural Foundation, research funding from Business Finland, official Finnish government agency for trade, and investment promotion, innovation funding, travel promotion, and talent attraction; and pending patent application WO2023187258 (A1)—ASSAY FOR LONG FORMS OF CARDIAC TROPONIN T., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: The current biomarkers for diagnosis and monitoring of injured and diseased skeletal muscles, such as creatine kinase (CK), have limited tissue specificity and incapability to differentiate between pathological and physiological changes. Thus, new biomarkers with improved diagnostic accuracy are needed. Our aim was to develop and validate a novel assay for skeletal troponin I (skTnI), and to assess its clinical performance in patients with idiopathic inflammatory myopathies (IIM)., Methods: A two-step fluoroimmunoassay was used to analyze samples from healthy reference individuals (n = 140), patients with trauma (n = 151), and patients with IIM (n = 61)., Results: The limit of detection was 1.2 ng/mL, and the upper reference limit (90th percentile) was 5.2 ng/mL. The median skTnI concentrations were

Aims: The objective of this study is to evaluate the feasibility of transoesophageal echocardiography (TOE)-guided cardioversion (CV) of atrial fibrillation (AF) in daily clinical practice., Methods and Results: Transthoracic echocardiography and TOE were performed in 346 consecutive patients with AF lasting longer than 48 h or of unknown duration. If no intracavitary thrombus was found, CV was performed within 24 h of the TOE examination. Anticoagulation with subcutaneous low-molecular-weight heparin and warfarin was always started before CV. Warfarin was continued for at least 1 month after CV. The predictive value of several echocardiographic parameters including peak left atrial appendage emptying velocity (PLAAEV), left ventricular ejection fraction, left atrial diameter, and spontaneous echo contrast for the initial and long-term success of CV were evaluated. Transoesophageal echocardiography revealed no thrombus or other contraindications to CV in 274/346 (79%) patients. Early CV restored normal sinus rhythm or pacemaker rhythm in 90% (246/274) of the patients. One patient (0.3%) had a stroke within 30 days after CV. Peak left atrial appendage emptying velocity was significantly lower in patients with contraindications to early CV (P<0.001). However, neither PLAAEV nor any other echocardiographic parameter predicted the initial success of CV and the maintenance of sinus rhythm during long-term follow-up., Conclusion: Early TOE-guided CV with short-term anticoagulation is a safe and clinically effective alternative in treatment of AF lasting longer than 48 h or of unknown duration. The initial and long-term success of CV cannot be reliably predicted by echocardiographic parameters.