Background:Recent research indicates that high cTnT concentrations may be present in patients with various skeletal muscle diseases without apparent cardiac disease. Patients with PAD and chronic limb ischemia experience muscle destruction and regeneration, but it's unclear if the same phenomenon is responsible for the high cTnT concentrations. Chronic respiratory muscle ischemia and injury in moderate or severe COPD may also contribute to elevated cTn levels.The Tropolimb study is a prospective multicenter observational study enrolling patients with lower limb ischemia undergoing vascular surgery and patients with moderate or severe COPD undergoing thoracic surgery. The aim of this project is to evaluate cTnT and cTnI concentrations, measured with different hs-cTnI/T assays, in these patients and determine the source – skeletal muscle or heart – of these possible cTnT and/or cTnI elevations. Type:Investigator initiatedTrial Status:Enrollment active, ongoing data analysisEnrolling Centers:Switzerland: University Hospital BaselCantonal Hospital BaselCore Study Team Basel: