Arteries Secretly Re-Clog After Angioplasty More Than Half The Time

“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 also identified three factors that seem to influence whether patients are more likely to develop symptomless, or “silent,” heart disease within six months after treatment. These factors are gender, the severity of the blockage at a six-month follow-up angiography, and the artery’s reference diameter (the diameter just before and just after the fatty obstruction).

Men were more likely than women to have silent restenosis (the re-narrowing of arteries after they are unclogged). The researchers suggest that the gender difference could be explained by the fact that women have smaller artery diameters. Other factors may also play a role, they add, citing that several studies have documented gender differences in treatment of patients with coronary heart disease, and that the initial diagnosis of angina is made later in women than in men.

Patients with less severe blockage and those whose arteries had a wider reference diameter were also more likely to have silent restenosis. For their study, the researchers defined restenosis as a 50 percent or greater narrowing of an artery. Of the 2,690 patients, 607 had a blockage of 50 percent or more in their treated arteries six months after their procedure. Of those with restenosis, 335 patients (55 percent) had no symptoms.

“We wondered whether there might be a subgroup of patients who should be targeted to have routine six-month angiograms following coronary-artery intervention,” Ruygrok says.

To answer that question, they compared 46 factors to see if any significant differences existed between patients with symptoms and those with silent heart disease. These factors included age, gender, smoking history, heart medication use, and certain physical characteristics of the heart artery.

“We were surprised that there were not more predictive factors, such as diabetes,” says Ruygrok, who is also an honorary senior lecturer at the University of Auckland.

“Even though these new data would not necessarily make us alter clinical practice – such as performing a routine, six-month angiography following coronary intervention – these three factors may raise our level of suspicion about patients in whom the clinical diagnosis is not clear-cut,” he says.

Restenosis occurs in 10 percent to 40 percent of patients, according to various studies. Previous research has indicated that a significant number of patients who develop restenosis do so without symptoms, particularly chest pain known as angina.

“This occurred in 55 percent of those with restenosis in our study, which in itself is an interesting finding,” says Ruygrok. “These people remain well, but with a potentially significant coronary problem.”

For their study, he and his colleagues combined and analyzed the records of 2,690 patients treated in 10 studies for obstructed heart arteries. The patients either had balloon angioplasty or insertion of a stent – a flexible, mesh tube used to help keep arteries open. All of these procedures are nonsurgical but require threading a catheter into a heart artery narrowed by fatty deposits to restore blood flow to the heart muscle.

In addition to an artery-opening procedure, each patient also had an angiographic examination of their heart arteries six months after their treatment. “Angiography, which is not the usual clinical practice after these interventions, is the only definite way to identify silent restenosis,” Ruygrok notes.

Co-authors were Mark W. I. Webster, M.B.Ch.B.; Vincent de Valk, Ph.D.; Gerrit-Anne van Es, Ph.D.; John A. Ormiston, M.B.Ch.B.; Marie-Angèle M. Morel, B.Sc.; and Patrick W. Serruys, M.D., Ph.D.