The Cardiospec technology has already been used to treat about 1,000 patients worldwide, in Europe, Canada, and other regions around the globe. And so far, it seems that about two to three years after the original treatment, patients can experience a relapse. Many patients who undergo treatment don't change their exercise habits or diets, their blood vessels begin to narrow, and once again their hearts can't get enough oxygen. "It's like when patients have undergone a stenting procedure," Hakim says. "That won't necessarily be the only stent, because they develop another problem in another area in the heart."

It's not that the shockwave treatment has failed. Rather, a patient ends up with the same problem in a different region of his heart. "It's like maintenance--after a few years, patients can be evaluated, checked again, and then retreated," Hakim says.

The options available for so-called "refractory angina" patients, who have pain after surgery or aren't candidates for surgery in the first place, are quite limited, says Timothy Henry, an interventional cardiologist at the Minneapolis Heart Institute who's not involved in the trial. "We definitely need new options, and this is an interesting one. The preliminary data looks very good, it's low risk. I think this is a really good option, but it needs to be tested," Henry says.

Lerman and his collaborators hope to complete the safety trial in a few months, and Medispec is aiming for U.S. Food and Drug Administration approval by 2012. Hakim is hopeful that the technology can provide relief for patients who are now completely dependent on oral medications to stem the tide of their angina attacks. "On average, before starting the treatment, the patients took their medication around three times a day. After the therapy, they're taking it around three times a week. It's a marked improvement in their quality of life," he says. "It's not a cure, but it's an improvement."