Some smite spells for paladins have additional on-going effects for a mob hit by them.
i.e wrathful smite causes a mob to be frightened until they succeed a wisdom save or until the spell ends. The spell duration is 1 minute and requires concentration.

If a paladins hits a creature with wrathful smite and it fails the initial wis save and becomes frightened,  and if the paladin then casts a different spell that requires concentration (like shield of faith) does this change what he is concentrating on, meaning the effects of wrathful smite ends straight away and the creature is no longer frightened as the spell has ended, or does the creature continue being frightened until the minute is over or until they pass a wis save?