Your shortness of breath and your angina pain have been getting worse. You are worried that these could be warning signs of a heart attack. Your cardiologist unclogs your artery and puts in a stent to keep it open. The operation is successful and you feel better.

End of story?

For their study, the researchers defined restenosis as a 50 percent or greater narrowing of an artery.

Perhaps not, according to a new study published in the 11/5/01 issue of Circulation, the journal of the American Heart Association.

"These patients may have a silent risk of future coronary events, such as a heart attack," says lead author Peter N. Ruygrok, M.B.Ch.B., consultant cardiologist at Green Lane Hospital in Auckland, New Zealand. "Yet, they believe they have had a successful treatment for their obstructive artery narrowing."

The study found that a significant percentage of people who underwent a procedure to open up a narrowed artery began to develop symptomless ("silent") heart disease within six months after treatment. With alarming speed, the plaque within their arteries that caused the original problem had begun to rebuild and create new areas of narrowing, a process called "restenosis."

For their study, the researchers defined restenosis as a 50 percent or greater narrowing of an artery. Of the 2,690 patients they followed, 607 had a blockage of 50 percent or more in their treated arteries six months after undergoing either angioplasty or insertion of a stent (a flexible, mesh tube) to help keep arteries open. Of those 607, 335 patients (55 percent) had no symptoms and no idea that they might need further treatment.

"This in itself is an interesting finding," says Ruygrok. "These people remain well, but with a potentially significant coronary problem." It is also higher than would be expected based on previous studies, which had indicated that restenosis occurs in 10 to 40 percent of patients.

To the authors of the study, these findings raise the question of whether more angioplasty and stenting patients should be given an angiogram six months after their operations. Angiogram is an expensive and invasive test that allows doctors to measure the degree of narrowing in a particular section of artery. It is not normally done in the absence of serious symptoms.

"Angiography, which is not the usual clinical practice after these interventions, is the only definite way to identify silent restenosis," Ruygrok notes.

TheDoctor's cardiovascular expert, Richard Smalling, M.D., Ph.D., Jay Brent Sterling Professor of Cardiovascular Medicine at University of Texas Medical School at Houston, accepted the data but remained skeptical about some of the study's conclusions.

"It is true that restenosis occurs in about a third of patients," Dr. Smalling said. "Still, if a 75-80% diameter stenosis is cleared but after six months regresses to a 50% narrowing, is that a bad thing? Most cardiologists would argue that the patient is still better off. We do not always get perfect results from angioplasty or stenting, but the vast majority of patients are happier and healthier."

"A common cause of heart attack is unstable plaque breaking open," Dr. Smalling added, "stimulating a blood clot to form within the artery and causing a sudden blockage of blood flow. For this reason, transforming a 75% narrowing with an unstable plaque into a 50% narrowing with stable plaque is probably a very good thing to do."

"The treatment of coronary artery disease is evolving very rapidly," Dr. Smalling said, "thanks to a host of new stent coatings, radiation techniques, and other advances, we may soon eliminate the restenosis problem almost entirely."

Reviewed by: Richard W. Smalling, M.D., Ph.D.