Monday, March 26, 2012

Cardiac stress test before endurance exercise might just make sense

The party line (I mean the consensus of reasoned expert opinion by panels of highly educated people) has been there should not be stress tests before a person begins training for or entering a marathon because of some combination of the following reasons: low incidence of cardiac events in endurance races and shorter fun runs,large numbers of false positives noted on treadmill stress testings,and the dominant theory that the major cause of cardiac events precipitated by exercise is acute plaque rupture rather than fixed coronary artery stenosis.

An extensive assessment of cardiac events during long distance runs might change the thinking in that regard.

JH Kim et al reached that conclusion following their analysis of cardiac arrests associated with marathon and half marathon races in the US from 2000 to 2010.See here for ref.

The authors' data including races involving 10.9 millions runners and 51 men had cardiac arrests. Hypertrophic cardiomyopathy and atherosclerotic coronary disease were the two most common causes.

The authors said:

"The absence of coronary plaque rupture in these persons was surprising because prior data and expert consensus documents have suggested that exercise induced acute coronary syndrome result from atherosclerotic plaque disruption and coronary thrombosis.

Their findings suggested that rather than plaque rupture that there was an imbalance between oxygen supply limited by stenotic coronary arteries and oxygen demand greatly increased by the exercise.

So exercise testing would be useful to the extent that the exercise related events were due to fixed obstruction. Of course both mechanisms could be present alone or in combination in various people. A resting ekg should be helpful in alerting to the possibility of hypertrophic cardiomyopathy. But, of course, there is that new directive by the progressive medical elite for parsimonious care to take under consideration.

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