Thursday, December 07, 2006

Athelete's heart or early CAD

Is there such a thing as the athletes' heart? I am encouraging my patients to exercise as a means of primary protection against coronary heart disease. Some of my patients are quite serious about exercise and in fact are runing regularly with the hash harriers and pacemaker clubs. In fact a few of them are running 40 Km marathons regularly. Is this wise?

When we see "fit" well trained patients with a low heart rate and enlarged heart, we attribute all this to their fitness and regular exercise. The enlarged heart we call "athlete's heart". But is there such an entity and is it normal. We have written earlier, that marathon running can be associated with rises in CKMB and troponin T, suggesting myo-sacomere destruction with marathon running.

At the recent AHA annual scientific meeting in Chicago, Dt Stephan Mohlenkamp presented the Master Marathon Study. They studied about 100 marathon runners (run at least 20 marathons over the last 20 years), who had a low cardiac risk profile using the Framingham Scores. They subjected these runners to echocardiograms, the MSCT and the Calcium score, and found that many of them had enlarged heart with increase calcium score, suggesting that these marathon runners in fact may have subclinical CAD.

A week later, at the American Radiological Society Annual Scientific meeting, also held in Chicago, Dr Torleif Sandner of Munich also presented another study done in on the same population of now 110 marathon runners, now average years 57, to MRI scans of the heart in an attempt to measure their LV mass. They found that these marathon runners all had an increase LV mass of 150 grams or more. Obviously this second study was done in collaboration with the first study. When they compared their studies, they found that those runners with higher calcium score also had higher LV mass, suggesting that the increase LV mass may be related to early CAD as suggested by the increase calcium score. Interesting.

I have never been a firm believer in calcium score having a positive correlation with presence of CAD. I have always thought that zero calcium score is better correlated with lack of CAD. Anyway, I thought it interesting that fit marathon runners should be careful. You may have early CAD. If that is true, it further supports the earlier posting that the rise in CKMB and Troponin T may be due to some degree of heart muscle damage from micro-infarcts. Marathon runners beware.

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