My 2011 bike crash had me off for only 4 months due to C6 and clavicle fracture, C5-C6-C7 compression/shifting resulting in Long Thoracic Nerve damage and even with resulting issues to this day recovery was possible. Resting HR before/at time in ICU of the crash was 38bpm and 2 years ago before my first prostate cancer treatment it was 32BPM, so return to pre-crash condition is possible just time consuming. My first IRONMAN was 2013 and I fared fairly well considering my 63yo body was beat up. My suggestion is to follow doctor/therapist recommendations and give yourself time to recover.
Had a total right shoulder joint replacement last October and my first swim test will be next week with results helping to determine if I try another IM in 2019. My
first priority however will be to improve on my 307 miles in 22 hours this past Bike Sebring 12/24 Hour Race to 400 non drafting miles in the 2018 Bike Sebring 12/24 Hours for a RAAM Qualifier Classification.
Good luck with smooth roads ahead.