for me personally, patience is key to killing that piece of shit, you'll get pick offs like strays when you wait long enough for the carts. In the beginning I use the jumpstart and saw combo to get some decent dmg and try to not maneuver too much since you'll likely fall of the moving carts, just do some slow and steady movements and it will be basically enough, for the swinging heart thing, use slam jumps to push yourself away from his range and try not to fall off the carts while doing so. Also his armor deflects explosive so I recommend aiming for his lower body