A 41-year-old woman was visiting Oxford, where she had a sudden cardiac arrest. Cardiopulmonary resuscitation was started by a bystander until the paramedics arrived, who found her in ventricular fibrillation, and delivered three shocks. After 28 min she had return of spontaneous circulation. Emergency coronary angiography revealed normal coronary arteries. Echocardiography followed by a cardiac MRI showed non-dilated left ventricles with no evidence of late gadolinium enhancement. She had a single-chamber implantable-cardioverter defibrillator (ICD). A chest CT showed sternal fracture and subsegmental pulmonary embolism, for which she was anticoagulated and was discharged.Several days later, the patient presented to another hospital with atypical chest pain and dizziness. She had haemodynamic instability and echocardiography showed the ICD lead perforating through the right ventricle, with a large pericardial effusion and tamponade, for which pericardiocentesis was done. Afterwards, the patient had repositioning of the ICD lead safely.