A potentially fatal heart condition known as hypertrophic cardiomyopathy or HCM is exceedingly rare in highly trained athletes, according to a study by the cardiologist in charge of the UK’s program for screening top athletes’ hearts.

Among 3,500 national- and regional-level athletes tested between 1996 and 2006, Dr. Sanjay Sharma of King’s College Hospital in London and colleagues found just two possible cases of HCM, suggesting a prevalence of “no more than” 0.06 percent among elite athletes, compared to 0.2 percent in the general population, they report.

HCM is a relatively uncommon disorder in which the heart muscle becomes enlarged, interfering with normal cardiac function. Thickening in muscle fibers is usually greatest in the walls of the left ventricle, the heart’s main pumping chamber. This thickening reduces the size of the pumping chamber itself, which in turn hinders blood flow. HCM has been implicated in the sudden deaths of some young, fit individuals.

“Structural and functional changes associated with HCM naturally select out most individuals from competitive sports,” write Sharma and colleagues in the Journal of the American College of Cardiology. People with HCM probably are not able to reach the level of fitness required for competitive sports, Sharma added in an interview with Reuters Health.

In their study, the researchers did pick up 15 athletes with either Wolff-Parkinson-White syndrome or a long QT interval, both of which are electrical abnormalities of the heart that could lead to sudden death. The defects were identified using an electrocardiogram or ECG.

The findings in this study, Sharma and colleagues say, demonstrate that ECGs are adequate to screen elite athletes for HCM and other heart defects. While the 3,500 athletes in the current study also underwent echocardiograms, a more expensive and complex test that evaluates the structure of the heart, they say this isn’t cost effective.

To date, Sharma has screened an additional 8,000 athletes using ECG alone, 4 percent of whom were brought back for an echocardiogram. “In the vast majority of those 4 percent, we don’t find anything,” Sharma said. “We have followed up these people for 12 years (and) we have not had a single athlete die that we’ve cleared to date.”

But in an editorial published with the study, two doctors argue that professional athletes should undergo screening echocardiography, given that the test can identify other dangerous structural abnormalities and may also be useful for evaluating symptoms that may develop later on.

The very low prevalence of HCM that Sharma and colleagues identify “should be taken with caution” given that most of the athletes screened were Caucasian, write Drs. Lothar Faber and Frank van Buuren of Ruhr-University Bochum in Bad Oeynhausen, Germany.

They also contend that the costs of screening “appear to be absolutely negligible” in the context of the billions spent in professional sports. “Even the amateur marathon runner can be reassured that the price of a screening echocardiogram is probably less than that of the latest running shoes,” Faber and van Buuren write.

SOURCE: Journal of the American College of Cardiology, March 11, 2008.