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Monday, October 02, 2017

Another study demonstrating more coronary calcifications and myocardial fibrosis in Older endurance athletes

The article by Merghani et al (1) at least at first glance seems to be more bad news for long time endurance athletes in regard to the development of coronary artery disease.

The study subjects were 152 men who had logged an average of 31 years of endurance exercise type activities. All had echocardiograms,24 hour Holter, stress ECG,CT coronary angiograms (CAC) and cardiac MRs with gadolinium as did 92 age matched controls with similar Framingham Risk scores.

15  athletes and none of the controls had delayed gadolinium enhancement (DGE) on the MRs, 7 of which had a coronary artery pattern.(The DGE issue  will need to be written about at a later date-for now  the focus is on the  calcification.)

60% of the athletes and 63% of controls had a normal CAC score but only athletes (11.3%) has a CAC score of 300 or greater. So the incidence of any calcification was about the same in athletes and controls but the athletes had more calcium and more demonstrable luminal stenosis ( greater than 50%) in 7.5% of the athletes and in none of the controls.

So does this mean that long time endurance exercise increased the risk of coronary artery disease?
Maybe an answer to that is related to another question-does the increase in calcium scores noted in patients taking statins mean that statins increase the risk of coronary artery disease which is , of course, a conclusion contrary to realms of clinical trial results demonstrating the value of statins, at least in secondary prevention.

In regard to the second question there is a great deal of data regarding what could be called the statin plaque paradox-statins increase coronary artery calcium even as they shrike the plaques. A  calcium score could increase even as the plaques regress because of the increased density of calcification bought about by the statins.However not only did Merghani's runners have higher Calcium scores a few did have luminal stenosis related to the calcification.

A review of serial coronary intravascular ultrasound (IVUS) data gathered up from 8 large clinical studies  may shed some on light on that issue.

The bottom line is that statins may increase the calcium scores (Agatson score) by increasing the calcification of plaques while decreasing the volume of the plaques, the effect being greater with the more potent ( as measured by magnitude of cholesterol lowering) statins having a greater plaque shrinkage  effect.My sense of the literature is that other than the more fringy group of "statin deniers" there is no abundance of data suggesting that statins increase the risk of coronary heart disease.

More possible good news for long term exercisers who have already made up their minds that what they do is good,  can be found in  a 2016 article  (2)Shuaib Abdullah and Benjamin Levine reviewing their data of healthy exercisers stratified by exercise levels  and previous articles that made the association between myocardial fibrosis ( as indicated by late  gadolinium enhancement (LGE) on cardiac MRs) concluded "that increasing levels of lifelong physical activity were not associated with focal myocardial fibrosis ".Although some athletes may demonstrated LGE the authors suggest that they may not represent fibrosis but rather possibly "exaggeration of the normal local myocardial architecture or edema caused by exercise-induced right ventricular overload and paradoxical septal motion".The more commonly expressed view is that LGE is more common in endurance athletes and  does represent fibrosis typically at the insertion points of the right ventricle to the left but their significance is not known. 

No one since a pathologist decades ago (Tom Bassler) ( footnote 1)  would now that endurance exercise is completely effective immunization against coronary artery disease but there will be a major paradigm shift if and when it is more conclusively shown that long term endurance exercise increases the risk of coronary artery disease.

Quoting from Levine ( ref 3):


"Although it would be foolish to argue that extraordinary endurance exercise can never be harmful, it is equally inappropriate  to frighten individuals who wish to undertake competitive endurance training, including marathons,triathlons, or even ultra endurance events, based on fear of accelerating coronary artery disease or initiating a cardiomyopathic process." [ Levine does not however, deny the epidemiologic evidence that there is a increase risk of atrial fibrillation though there are conflicting data and the magnitude of the putative risk is a open question]

Sorting out cause and effect is no easy matter and may not be possible   in cross sectional, observational  studies in conditions in which there is a high "causal density".The relationship between exercise levels, intensity of statin therapy and the list of  recognized coronary artery disease risk factors is by no means unraveled.



1)Merghani, A et al Prevalence of subclinical coronary artery disease in Master Endurance Athletes. Circ. 2017, May 2, 2017 Vol 135, issue no 12

2) Abdullah, SM et al Lifelong physical activity regardless of dose is not associated with myocardial fibrosis. Circulation Cardiovascular Imaging, 2016;9  e

3) Levine BD Can Intensive exercise harm the heart? Circulation 2014: 130, 97-99L

Footnote 1 Dr.Thomas J Bassler actually was slightly more circumspect saying that if one could finish a marathon in under 4 hours he would not  die of a heart attack in the next 6 years. He wrote and spoke often in the 1970s about the value of long distance running. He died Dec 2011 at the age of 79 . Maybe his best quote is (paraphrased):

 If you decide to lead a sedentary life style better see your doctor first.


Footnote 2  and disclosure

Paul Simon's lines  ( a man believes what he wants to believe and disregards the rest )
is a modern musical echo of  Hume's comment that reason is the servant of passion .

My history of marathon running over 40 plus years may well reveal
my biases.

11/13/17 Footnote 2 added as well as adding a new final paragraph.

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