Randomization: At the time of implant 1:1 randomization (100 patients in each group) to either subcutaneous (usual care) or intramuscular implant, in blocks with random block sizes. The randomization is performed by a statistician with no insight in the ongoing clinical work and patients' group allocation is revealed for implanting physician by the assistant nurse at the start of the surgical procedure. Randomization procedure: stratification (age strata: ≤65 years and >65 years) and sex (female, male); totally 4 strata). Consecutive group allocations will be stored in sealed opaque envelopes that will be opened at the time of starting the implant procedure.