By Barnaby J. Feder
New York Times
Copyright 2007 The New York Times
BEDFORD, Mass. — A diagnostic test intended to identify patients who should receive heart defibrillators did not produce conclusive data, according to initial results from a clinical trial presented yesterday at the meeting of the American Heart Association.
The trial is among the most rigorous yet for a test made by Cambridge Heart, a start-up company in Bedford, Mass. The test monitors variations in a portion of the heartbeat called the T-wave while a patient exercises.
Cambridge Heart has argued that the test can solve one of the more vexing problems in cardiology — the inability of doctors to predict which patients with damaged and failing hearts were most likely to suffer the potentially fatal rhythm problems that can be corrected by a shock from an implanted defibrillator.
However, the preliminary results of the clinical trial indicated Cambridge Heart’s test had little predictive value. Defibrillators have saved thousands of lives. But studies have shown that well over half the patients who undergo the risks of getting the implants, which cost as much as $35,000, never need a shock.
Called Master 1, the trial was sponsored by Cambridge Heart and Medtronic, the leading maker of defibrillators. The trial monitored a group of patients who all had the devices.
According to Cambridge Heart’s theory, a person with a normal T-wave would rarely require life-saving shocks from their defibrillators.
In the clinical trial, while the 575 patients with normal T-waves received somewhat fewer shocks, the difference was so small that it might be a matter of chance. And so the Cambridge Heart test could not be relied on to separate which patients actually needed the defibrillators.
Cambridge Heart’s shares lost nearly a third of their value, falling 75 cents, to $1.53.
The company said the trial might be flawed because it used shocks from the devices as the measure of which patients suffered life-threatening heart irregularities.
Such devices are known to sometimes give shocks in response to nonlethal signals.
A second portion of the trial, Master 2, will compare the T-wave’s performance as a predictor of seizures in patients who did not get defibrillators with the group that did get the implants.
“These results are not a reason to abandon T-wave research,” said Kyra Schmitt, a spokeswoman for Medtronic.