You can see the contrast washing at the LM, and looks connected to another vessel, most likely pulmonary artery. ALCAPA (anomalous origin of left coronary artery from pulmonary artery). Usually detected earlier in life. Symptoms can vary from CP to SOB and can cause a CMP. Over the years R-L collaterals develop and help with symptoms. Main way to treat this condition is surgically. Either ligation of LM and bypassing with a LIMA or reimplantation of the LM it the left coronary cusp and creating a neo ostia. Not common, I was lucky enough to see one so far and she was in her early forties. Nice case :)