Plague Hearts in State of Decay 2 are tough to destroy, but with the right preparations you can take them out fast and easy.
Important to note is that the plague hearts will get increasingly difficult with each one you destroy. So keep in mind to be more careful the further you go in the game.
HOW TO PREPARE FOR PLAGUE HEARTS
Always try to bring your best available gun with you alongside molotovs and other explosives to deal enough damage. Also pack firecrackers and boom boxes for distractions. Molotovs and firecrackers can be crafted in the workshop by finding a small shelter slot. Without much resources you can re-stock here every once in a while.
HOW TO DESTROY PLAGUE HEARTS
Find a plague heart on the map by looking for red infested houses. Place a boom box or firecrackers outside as a distraction and instantly go to work on the plague heart inside. Use molotovs, grenades and you gun to deal as much damage as you can. At the same time listen to your distractions and place a new one if needed to keep the zombies away.