The nuclear stress test, which uses thalium to show how well blood flows to the heart, is much more accurate than the exercise stress test, says Barbara Andrewin, an EKG clinical technician at St. John's Health Center in Santa Monica, Calif.

"The nuclear stress test is more definitive," she says.


It's 90 percent effective in diagnosing cardiac problems, says Andrewin.

Andrewin points out that physicians "really don't like doing [exercise stress tests] because [they're] wasting a lot of time," when a physician knows the patient's history and knows the problem is heart-related.

But that doesn't mean the exercise stress test will become obsolete, as it is still a key tool in ruling out heart problems in healthy patients, says Andrewin.

"I don't think it will be phased out," she says. "Doctors believe in them. We still have healthy people that [think they have cardiac pain], but they're having GI problems...With that in mind, we're still going to do regular stress tests."

Something new in the sector

Today, companies are adding new testing features to the exercise stress test, allowing them to perform multiple tests at once.

One test in particular studies the microvolt T-wave alternans (MTWA) phenomenon, which is an indicator of a person's risk for sudden cardiac arrest - a leading killer in the United States.

"What's new for stress testing is that the addition of microvolt T-wave alternans testing may be the first significant change," says Ali Haghighi-Mood, CEO of Cambridge Heart. "[The addition of MTWA testing] has the potential to introduce a new standard for stress tests."

Cambridge Heart, based in Tewksbury, Mass., recently received FDA approval to sell its OEM module that uses the analytic spectral method of measuring MTWA. This particular method was originally developed by the Massachusetts Institute of Technology.

Lahn Fendelander, Cambridge Heart's vice president of clinical affairs, explains that the analytic spectral method is patented by Cambridge Heart and the only MTWA testing method that is Medicare-reimbursable.

"The traditional stress test, in layman's terms, is looking for a plumbing problem - coronary heart disease," says Fendelander. "The MTWA test looks for an electrical problem...By adding [the MTWA feature], if you do a stress test, you have assessment of the plumbing, and now you have assessment of the electrical."

Cambridge Heart has teamed up with Cardiac Science, a leader in stress testing equipment, to sell its MTWA module with Cardiac Science's equipment.

As far as trends go, other OEM, such as GE and Burdick, also have an MTWA test, and the trend seems to be growing.

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