For that reason, among others, not everyone is buying what EKGuard has to sell. "Patients who are worried enough to call someone because they're having chest symptoms really need to be seen by a physician, and been seen in an emergency room," says Richard Stein, MD, a spokesperson for the American Heart Association (AHA) and a cardiologist at Beth Israel Medical Center in New York City.

Stein argues that a normal EKG doesn't always carry enough information for a doctor to know whether there's cause for concern. "Somewhere between 20 percent of men and 25 percent of women have symptoms during a heart attack that aren't classic," he says, adding that early EKGs don't necessarily show telltale signs. Often, additional EKGs and blood tests are needed in order to rule out a heart attack, says Stein.

"I don't think that the assurance EKGuard can give is one I would want my patients to have," Stein says.

Lichtenstein, however, thinks that many of the people who might purchase his product and phone the call center are the type who might otherwise do nothing at all. "Research by the AHA has found that people just won't call 911" during possible cardiac emergencies, Lichtenstein says. But he believes they will call EKGuard.

EKGuard will be available in five to eight more states within a year, and nationwide by 2010, Lichtenstein says.

Meanwhile, the medical community has yet to pass judgment on handheld EKG units. Stein and others would like to see the results of clinical trials before they give their endorsement; while many others seem optimistic, given the technology's success in other countries.

If the service saves someone's life, the steep startup cost will seem like a small price to pay, of course. On the other hand, if EKGuard creates a false sense of security for those who should instead be racing to an emergency room, cardiologists may not be quick to embrace it.