All veins opens into coronary sinus EXCEPT:

Anterior cardiac vein "Anterior cardiac veins empty directly into the right atrium" VENOUS DRAINAGE OF HEA: The hea is drained mainly by veins that empty into the coronary sinus and paly by small veins that empty directly into the chambers of the hea. The coronary sinus the main vein of the hea, is a wide venous channel that runs from left to right in the posterior pa of the coronary groove.