Rupture of aneurysmal circumflex coronary artery into the left atrium after ligation of its arteriovenous fistula.

Aneurysmal circumflex coronary artery (Cx) with fistulous connection to the coronary sinus is a rare clinical entity that usually remains asymptomatic until later in life, so the ideal therapeutic strategy is poorly defined. The timing of surgical treatment for asymptomatic patients is a big issue, and whether to leave or exclude the diffuse aneurysm in addition to ligation of the fistula is controversial, considering the native myocardial circulation. Complete surgical repair, including exclusion of a diffusely aneurysmal Cx and coronary revascularization to a graftable branch in the circumflex area combined with ligation of its fistula, is quite challenging and sometimes fatal because of a broad posterolateral myocardial infarction without revascularization caused by a lack of graftable branches. A case of diffuse aneurysmal Cx, which ruptured into the left atrium after surgical ligation of its fistulous connection to the coronary sinus, is presented. Simple ligation of the fistula, leaving a gigantic aneurysmal circumflex artery, is hazardous for later rupture and should be avoided. Therapeutic strategies for this complex disorder are discussed, including the optimal timing of surgical treatment.