This is an updated guideline from the FSRH on the use of Levosert, a 52mg LNG-IUS, which is the same as Mirena.
It seems to be as effective as Mirena and to have similar side-effects.
It is now licensed for six yrs of use for contraception (initially it was only licensed for 3 yrs of use, then for 5 yrs of use). For the management of heavy menstrual bleeding, it is still only licensed for 5 years. There have been studies showing very good efficacy into the 6th year, even among younger users. One study is looking at use for up to 10 years, so it is possible that its license will be further extended in time.