Empty Heart

Empty Heart is an unlockable passive item added in The Binding of Isaac: Repentance.

Effects[]

If Isaac has one red heart or less at the beginning of a floor, an empty heart container is added.

As there is no special exception, this item will have no effect for characters that cannot have red hearts : Dark Judas, ???, The Lost, Keeper, The Forgotten, The Soul, Tainted Judas, Tainted ???, Tainted Lost, Tainted Keeper, Tainted Soul and Tainted Bethany.
The empty heart containers will replace any other heart containers if the maximum has been reached.

Crow Heart: If no Devil Beggars or Blood Donation Machines can be found, the Crow Heart trinket is a great way to guarantee red hearts are lost so long as you still have non-red health available.
Guppy's Paw: The heart containers granted by Empty Heart can be used by Guppy's Paw while staying at or below 1 red heart, granting massively increased survivability.
Lazarus: The heart containers granted by Empty Heart allows Lazarus to effectively negate the downside that removes a single heart container on death, allowing him to purposefully use his mechanic to get a +0.5 damage up per floor. (As long as he still proceeds at one red heart or less)
Potato Peeler: The heart containers granted by Empty Heart can be used by Potato Peeler while staying at or below 1 red heart, granting increased damage and a Cube of Meat per floor.

Bug!	If Isaac is operating only on soul hearts and manages to get 12 empty heart containers by using this item, he will die immediately upon leaving the spawn room or picking up an item.