Ablation in the left atrium have become standard of care for patients with atrial fibrillation, however it may be associated with severe complications. On line imaging using intracardiac echocardiography (ICE) is one of modern options to visualize cardiac chambers during the procedure, which allows early detection of complications and prompt treatment. We present a case of a 69 year old female who developed massive thrombi in right and left atrium, followed by thrombosis of coronary arteries and haemodynamical complications. Rapid detection of these phenomena using ICE enabled prompt effective treatment and good outcome.