In recent years, new techniques and materials in interventional cardiology have improved patient safety significantly. This led to the ability to perform more and more complex coronary interventions with a minimal risk for relevant complications. However, perforation of distal coronary vessels by guide wires is still observed and can lead to a life-threatening pericardial tamponade. Various treatment options have been described but management of this particular complication remains a challenge for the interventional cardiologist. So far, the treatment of choice for many cardiologists is the application of coils [1, 2]. But coils have some major disadvantages; they are sometimes difficult to position and are often not routinely available in cath labs. Other proposed methods include long inflation of over-the-wire balloons which is easy to handle and can be considered as a temporary solution to gain time, but is often not sufficient to stop the bleeding [3]. Implantation of covered stents can also be considered, but is not suitable in small vessels or lesions not reachable with a stent for other reasons [4, 5]. Administration of protamine might facilitate measures to seal a coronary perforation but might also lead to intracoronary thrombus formation or even stent thrombosis [6]. Microspheres are small spherical particles made of various materials with diameters ranging between 1 and 1,500 lm. Such particles are used for a broad spectrum of percutaneous interventions. They found their way into interventional cardiology as an alternative to ethanol for transcoronary ablation of septal hypertrophy (TASH) in hypertrophic obstructive cardiomyopathy (HOCM) [7]. Despite the fact that some authors suggested the use of different kinds of microspheres for coronary perforation, this technique did not find its way into clinical routine so far [8, 9]. This might partially be due the fact that the optimal size and material of microspheres remain uncertain. Patient #1 was admitted to the emergency department with ST-elevation myocardial infarction and was transferred to the cath lab immediately after admission. Emergency coronary angiography revealed an ostial occlusion of the left circumflex artery (LCX) which was treated with balloon angioplasty and implantation of an everolimus eluting coronary stent. For this purpose, a PT Graphix guide wire was placed distally in a marginal branch. The patient was provided with a loading dose of aspirin and ticagrelor. In addition to that, due to a heavy thrombus burden, abciximab was administered intravenously. After successful revascularization, the patient was referred to the intensive care unit for further surveillance. Two hours later the patient became hemodynamically unstable and had to be treated with catecholamines. Echocardiographic evaluation revealed cardiac tamponade as the underlying cause. Pericardial paracentesis was performed immediately and led to hemodynamic stabilization by drainage of 500 ml blood. As a coronary perforation seemed the most likely cause, coronary angiography was performed, showing a leak of contrast dye into the pericardium at the marginal branch of the LCX in which the wire was positioned during the prior intervention. Occlusion of the lesion by balloons did not lead to a sustained sealing. Therefore, decision was made to inject in total 3 ml of 75 lm Embozene microspheres (CeloNova BioSciences, San Antonio, TX, USA) F. Meincke (&) K.-H. Kuck M. W. Bergmann Department of Cardiology, Asklepios Klinik St. Georg, Lohmuehlenstrasse 5, 20099 Hamburg, Germany e-mail: f.meincke@yahoo.com