My string of hearts is undoubtedly the cutest houseplant in my collection. Long strings adorned with heart-shaped leaves never fail to capture my guests' attention. But, when these plants drop their leaves, the bare strands aren't so attractive.
It's a common problem when growing a string of hearts (whether a standard variety or a variegated string of hearts, like this from Walmart). Prolonged drought, incorrect lighting, pest problems, and other issues can all result in leaves dropping quickly and even contribute to the gradual decline of the the plant.