For coronary artery spasm , which medication is more effective, cartia or cardizem ?

Should be the same: Both Cartia XT & Cardizem are diltiazem, a calcium channel blocker. These drugs relax your heart muscle & coronary arteries. Cartia XT is a longer acting/sustained release preparation. Often this is prescribed in order to simplify your drug taking regimen, having to take Cartia XT only once a day. But ? more expensive. It probably is a choice between convenience & cost:)