Coronary artery fistulas are extremely rare and coil occlusion by intervention techniques seems to be the therapy of choice. We describe the case of a 3-month-old infant with a coronary artery fistula. During occlusion of the fistula a coronary guide wire got entrapped in a small coronary branch, but could be successfully retrieved with a microsnare without damage to the heart. The microsnare technique prevented rupture of the guide wire.