An apparatus is provided for reducing the formation and migration of blood clots from an atrial appendage, such as the left atrial appendage, to the blood vessel system of a patient. The apparatus comprises an atrial pacer to treat non-rheumatic atrial fibrillation (NRAF) of an atrial appendage so that the formation blood clots within the atrial appendage is decreased or eliminated. In addition, the apparatus includes a blood clot filter supported by the atrial pacer proximate the atrial appendage and the atrium to reduce the migration of blood clots from the atrial appendage into the blood vessel system of a patient.