The authors report 4 cases of acute coronary syndromes with increased troponine levels during junctional tachycardia in patients with angiographically normal coronary arteries. ST segment changes during junctional tachycardia have no predictive value for the detection of coronary artery disease. Increased troponine, a marker of myocardial cellular necrosis, is not a sign of coronary lesions. A disequilibrium between the increased metabolic and energetic requirements of the myocardium and decreased perfusion due to the tachycardia could explain this observation. The recommended management of these patients is not to perform coronary angiography initially in the absence of cerebrovascular risk factors, but rather to document myocardial ischaemia by a non-invasive method such as echocardiography or scintigraphy.