The damaged stems will not survive.
It might be possible to save the shrubs by cutting off all of the stems just below the damaged portions (rejuvenation pruning). The following bulletin (paragraph 4) describes this pruning method. If you cut off the damaged stems, do it as soon as possible.
Although only stubs will remain after pruning, the plants may fully recover. If the plants and roots were healthy before the damage occurred, new growth sufficient toplease your eye may be present by late summer or at the latest after the 2020 growing season. Patience, winter protection and selective pruning of new growth for a few years will be needed to enable the plants to recover their existing height and form.