I'm 69 and have had little exercise and lousy diet. Last year I was in the hospital with Congestive Heart Failure. One coronary artery was completely closed, another about 90%. My ejection fraction was about 7%, normal is 60. I had 2 stents put in the artery that was 90% blocked. The other artery is still closed. They put in an ICD, similar to a Pacemaker.
To clean my arteries I started taking Arginine/Citrulline (~5g total) and R Lipoic Acid. Both have been proven to reverse atherosclerosis.
This year I went into the hospital again because my heart rhythm was abnormal and my ICD "kicked" me 6 times. In the emergency I was stabilized. I don't know what they did. That night I transferred to ICU. In the early morning my heart muscles were "locking up", unable to absorb oxygen, even with a respirator full on. There was no doctor on the floor. The head nurse gave me a fast drip 2 gram magnesium in my iv. My heart returned to normal in minutes. I read when someone has a heart attack, the first thing they do is give a magnesium drip.
Heart rhythm problems (PAC, PVC, palpitations, pauses, etc) they are all, imo, abnormal electrical signals going to the four heart chambers. What creates the electrical signals? Electrolytes; calcium, sodium, magnesium and potassium. They all need to be in the middle of the highly inaccurate serum blood levels. My magnesium was "normal"; 1.9,(1.6 to 2.6) yet my heart muscles locked up and it was a magnesium drip that saved my life. I received 2g of mag in the drip, it increased my blood serum level to 2.0 for a couple days and dropped back to 1.9. After leaving the hospital I had a lot of arrhythmia's. My cardiologist prescribed amiodarone. After reading it can cause irreversible lung damage which can become fatal. It also have a very long half-life. I refused to take it and started looking for alternatives.
I take supplemental arg/cit, mag, pot and 3g taurine. Taurine has tremendous benefits. It helps balance and regulates electrolytes. I previously read the above study of 10-20g of taurine with arginine. That's a lot of taurine. This is a dose to overcome a deficiency.
Magnesium also has tremendous benefits, including dissolving calcium deposits in the heart. I take liquid elemental magnesium, it is very powerful and no diarrhea.
After a few weeks, my arrhythmia's were dramatically reduced in number and milder, and I look forward to more improvement. My "recipe": arginine/citrulline to clean arteries, increase NO, and improve blood flow, sufficient levels of mag, cal, pot, sod, and taurine to regulate/balance the electrolytes.
This info may be more useful to your parents or grandparents.
One last thought, I have begun high-intensity exercise to create "collateral" arteries to make up for the one I have completely blocked.