There was no treatment for FDR's high blood pressure other than to keep Eleanor at bay and try to keep him as calm as possible from around 43'.
It's why he was in Warm Springs Georgia when he died instead of Washington D.C.
Well there was, but he may not have known about it...Dr Walter Kempner down at Duke had developed his Rice Diet, and it really does control hypertension. As well as some heart and kidney disease.
FDR either didn't know of it, or if he did know about it he didn't want to use it because it is a very restrictive diet.
Still a useful diet if you're dealing with these issues and have allergies to the usual drug treatment.
https://nutritionfacts.org/video/kempner-rice-diet-whipping-us-into-shape/
But the 20th Century did help him out in surviving polio, didn’t it?