Rapamycin use with atrial fibrillation

I have been successfully treating my atrial fibrillation with diltiazem and flecainide for 10 years. In the warnings that came with the 1mg coated rapamycin tablets, it said in a paragraph titled *“Inducers or Inhibitors of CYP3A4 and P-gp”, that diltiazem was one of several drugs that could cause an increase in Sirolimus blood concentrations and that the dosage may need to be adjusted.
I offer this so that everyone who is taking medication to treat afib is aware that rapamycin may affect that medication and also to get input from those who have had experience or knowledge they can share.


Malcolm Kendrick says 80% of afib is caused by magnesium deficiency. I got afib once and ended up in the hospital trying to figure out what was going on. Doubled my Magnesium to 400 before bed and I’ve never had trouble again.

Don’t know if this helps, but it may be worth what you paid. lol

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@jhipster Thanks for posting this, and welcome to the forum. @rberger may find this of interest…

Malcolm Kendrick is insane lol. There’s been extensive research on magnesium as an adjunctive treatment for atrial fibrillation and it has shown little to no effect. I’m glad to hear you’ve not had any more episodes, but most people with atrial fibrillation have far more complex pathology than simple magnesium deficiency.


No criticism intended, but part of your post seems erroneous. Diltiazem may increase rapa level, not the other way around. Shouldn’t be a problem for most people.
And btw, magnesium does not fix a fib.

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Agreed. I’ve had AF for 6 years.
I took magnesium till it was out the wazoo…didn’t do a damn thing.
Cutting right down on the booze helped, but didn’t stop it.


I appreciate your input, but I believe that is what I said…*“diltiazem was one of several drugs that could cause an increase in Sirolimus blood concentrations”.

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Sorry, maybe my mistake. When you said “ everyone who is taking medication to treat afib is aware that rapamycin may affect that medication”, it sounds like your saying that Rapa will affect A. Fib medicine. Was that you intent?

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No, the other way around - diltiazem, which Is taken for afib, could cause an increase in the concentration of rapamycin (aka sirolimus) in the blood.

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dilitazem made me pass out - dropped my BP so low. Propafenone worked fine and no issue with taking rapamycin

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Terrible confession to make here:

I got the quote from Malcolm from my brother who borrowed my copy of “the clot thickens” when he went ice fishing and brought it back looking like he cleaned a fish on it (or with it). He was a big fan of Malcolm and read the blog also (which I did not until now). I didn’t look it up until now and am not making excuses, posting it was all my fault. Taking this long was the fault of harvest. I’ve been in a state of cognitive dissonance since I knew there was something wrong here.

Malcolm was talking about preventing afib by taking Magnesium. He was going off of a study in Israel where they desalinate water and it also takes out the minerals, including obviously Magnesium.

I don’t know how large a post I can copy here and hope I don’t get in trouble, but I want to be fair to Malcolm and set the record straight. I’ll put it an a reply after this post.

Most people are probably blissfully unaware they need magnesium. If you don’t have enough, how would you know? The first recognisable symptom may be … suddenly dropping dead.

Israel gives us a stark warning of what happens when magnesium goes missing, with no-one noticing. For many years, most of the water supply in Israel has been provided by desalination. This process does not just get rid of salt (NaCl), it also removes the other salts, and minerals, at the same time.

In normal circumstances people get most of the magnesium they need from drinking water. Which means there was clearly a potential for a major deficiency problem building up in Israel. As most of their water contained nothing but pure H20.

Did anyone notice? As in, did anyone say, ‘golly I feel low in magnesium today, I must go and eat a substance high in magnesium…’ Nope. Did anyone die. Yup, they did. As outlined in the paper ‘Association between exposure to desalinated sea water and ischemic heart disease, diabetes mellitus and colorectal cancer; A population-based study in Israel.’ 1

There were possibly as many as 4,000 deaths a year:

‘An estimated 4,000 Israelis die in an average year due to an inadequate amount of magnesium in their bodies – and the amount they get from natural potable water sources is increasingly declining due to the growing desalination of sea water. The figure is 10-fold the death toll from road accidents.’ 2

The population of Israel is just over nine million. The equivalent death rate in the UK would be 30,000 deaths a year, or 180,000 in the US. A silent killer indeed.

Anyway, yes, magnesium is critical stuff. It is extremely important for health, especially heart health. It is required for the correct functioning of the electrical system in your heart, and a low level increases the risk of atrial fibrillation. Here from the paper ‘Low serum magnesium and the development of atrial fibrillation in the community: the Framingham Heart Study.’

‘…individuals in the lowest quartile of serum magnesium were ~50% more likely to develop AF…compared with those in the upper quartiles.’ 3

Unfortunately, despite its importance, we don’t feel magnesium depleted. We do not crave magnesium rich foods – as if we would have any idea what they might be … I certainly don’t. The symptoms of severe deficiency are also non-specific. The first symptom might be that your heart decides to stop beating.

It’s not just Israel. Here from the paper: ‘Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis.’

‘Furthermore, because of chronic diseases, medications, decreases in food crop magnesium contents, and the availability of refined and processed foods, the vast majority of people in modern societies are at risk for magnesium deficiency.’ 4

Have you ever heard of any of this? Did you even know you had magnesium in your body – or that it did anything important? I suspect not. However, from the same paper:

By Malcolm Kindrick:

‘…magnesium deficiency can lead to serious morbidity and mortality and has been implicated in multiple cardiovascular diseases such as hypertension, cardiomyopathy, cardiac arrhythmia, atherosclerosis, dyslipidaemia and diabetes. Unfortunately, the western diet is often low in magnesium due to the refining and processing of foods, and hypomagnesaemia is often underdiagnosed in hospitalised patients.’ 4

My advice, take a supplement. Especially if you live in an area with ‘soft’ water – which generally means not many minerals. Doubly especially if you have atrial fibrillation. It might just go away. How much do you need to take? Around 400mg a day is fine.