Before 50-ish years ago as far as I know most treatments for a heart attack didn’t exist. Most medications and supplements for hypertension, cholesterol, triglycerides, homocysteine, etc. either hadn’t been invented or nobody knew they worked on these issues. Or people didn’t know these issues affected heart disease (ie people didn’t know cholesterol played a role in heart attacks). So medications don’t seem like they were viable to treat and recover from one.
No angioplasties existed, no stents, no bypass operations, etc. So using that as a means of recovering didn’t exist either.
Lifestyle changes existed, but I don’t know if the connection was as well defined (ie if people knew how risky smoking was to the heart as an example).
However I know people survived heart attacks in the 40s, 50s, 60s, etc and lived productive lives after that, for decades or more.
So how were they treated before we had the knowledge and invention of the medications, surgery and lifestyle changes we have now, since many people still survived them?