A third goes into the coronary sinus vein, just beneath the left ventricle.
From the dailymail.co.uk
The coronary veins all empty into the coronary sinus which empties into the right atrium.
From the en.wikipedia.org
The coronary sinus lead wraps around the outside of the left ventricle, enabling pacing of the left ventricle.
From the en.wikipedia.org
The only angiographic finding associated with major complications was drainage of the coronary artery fistula into the coronary sinus.
From the sciencedaily.com
The coronary sinus is the end portion of a large vein at the back of the heart that receives blood from the heart's veins and empties into the right atrium.