Minimum threshold for high heart rate

Hello, 

My father wants to get a smartwatch as a gift for Christmas. He is interested in the Vívoactive 5.

He has a special medical condition and he would like to set up the abnormal high heart rate to something as low as 70bpm.

Do you know if it is possible, or is the minimal threshold for abnormal high heart rate 100bpm, like all the other smartwatch brands?

Second question, if not possible for the vívoactive 5, are there any other existing Garmin models where you could set up a high abnormal heart rate to 70bpm?

Thanks!