Coronary arteriovenous fistulas complicated by complete atrioventricular block: A case report

We report the case of a patient with bilateral coronary arteriovenous fistulas (CAVFs) connecting the right coronary artery and left circumflex coronary artery with the right atrium who had progression of first-degree atrioventricular (AV) block to complete AV block during a 4-year period. The His bundle electrogram revealed that the complete AV block was the result of a block at the level of the AV node. Dipyridamole stress thallium-201 myocardial imaging showed decreased perfusion in the inferoapical wall. Coronary angiography and computed tomography showed fistulas that arose from the AV nodal branch of the right coronary artery and from the distal portion of the circumflex coronary artery and drained into the right atrium. Because the fistulas were small, they were not repaired surgically, and a permanent pacemaker was implanted to treat the complete AV block. We presumed that the complication by complete AV block was due to abnormalities of the arteries feeding the AV node and chronic ischemia resulting from a coronary steal associated with the fistulas. To the best of our knowledge, this is the first report of CAVF complicated by complete AV block.