Mar 28 2011
While coronary artery bypass surgery has long been the standard treatment for patients with the most extensive forms of coronary artery disease, the results of a recent study by an international team of researchers suggests that advances in technology appear to be narrowing the "benefit gap" between the two approaches. The results of the study appear in the March 17, 2011 issue of the New England Journal of Medicine.
"For most patients undergoing revascularization to treat coronary artery disease, there is typically a choice between two treatments -- coronary artery bypass surgery (CABG) and percutaneous coronary intervention (PCI), a less invasive procedure also called stenting," said David J. Cohen, MD, MSc, Missouri Endowed Professor of Cardiovascular Research at the UMKC School of Medicine, Director of Cardiovascular Research at Saint Luke's Mid America Heart Institute and principal investigator of the study. "Although many studies have compared these two treatments, all of the studies to date have used older technology for the PCI procedures -- either plain balloon angioplasty or bare metal stents."
Over the past decade, however, PCI has been revolutionized by the introduction of drug-eluting stents, which are designed to release medication to prevent excess scar tissue formation, which can lead to a return of blockages within an artery after an initially successful procedure. The evolution of stent technology has led to substantially reduced rates of restenosis (re-narrowing of an artery after an initially successful procedure) and improved long-term outcomes, Dr. Cohen noted.
The purpose of the study by Dr. Cohen and his colleagues was to compare health status improvement and quality-of-life outcomes for patients with left main and three-vessel coronary disease who were randomized to undergo PCI with drug-eluting stents or CABG. Quality of life endpoints were assessed for 1,800 patients using standard questionnaires that are designed specifically for patients with coronary artery disease, most notably the Seattle Angina Questionnaire (SAQ), which was designed by John Spertus, MD, also a Professor of Medicine at UMKC.
The SAQ is a patient-administered questionnaire designed to measure functional status of coronary artery patients. It is composed of five scales to assess clinically important dimensions of coronary artery disease: frequency of angina (chest pain due to an inadequate supply of oxygen to the heart), angina stability, physical limitation, quality of life and treatment satisfaction.
Among their findings, the researchers noted that the SAQ angina frequency scale reported by patients improved substantially in both the PCI and CABG groups over one year of follow-up; however, the extent of benefit was slightly greater with bypass surgery. On the other hand, the researchers found that the less-invasive PCI technique did have substantial benefits in a variety of general health status measures including pain, physical function, vitality, and ability to perform one's daily activities at one-month follow-up. These differences were transient, however, and had largely resolved by six months.
"Another way to look at the results is that at one-year follow-up, there was complete relief of angina in 76.3 percent of patients treated with CABG and 71.6 percent of patients treated with PCI," Dr. Cohen said. "While this difference is statistically significant, it means that you would need to treat about 21 patients with CABG before you would have one additional patient who was angina-free at one year, as compared to PCI."
They also found that patients who had the most severe angina at entry into the study (daily or weekly angina in the month prior to enrollment), were a group that benefited preferentially from CABG. For those patients -- who represented about one-third of the patients enrolled in the study -- about one in 10 received a measurable benefit in terms of one-year symptom relief. For the other two-thirds of patients in the study who were less symptomatic at entry, the researchers reported no significant statistical difference between the two treatments.
"The main implication of these findings is that PCI has continued to improve such that the gap between it and CABG, at least in terms of quality of life, has narrowed considerably over the last 20 years," Dr. Cohen said. "Individual patients and their physicians will need to balance the much more rapid recovery after PCI with the possibility of slightly better relief of symptoms in the long run when deciding between these two different forms of therapy."
Dr. Cohen's co-investigators in the study included Elizabeth M. Mahoney, Sc.D. (UMKC and St. Luke's); Kaijun Wang, Ph.D. (St. Luke's); Ben Van Hout, Ph.D. (University of Sheffield, Sheffield, United Kingdom); Patrick W. Serruys, M.D., Ph.D. (Erasmus University Medical Center Rotterdam, the Netherlands); M.M. Vrakking, M.D. (Amphia Ziekenhuis, Breda, the Netherlands); Peter den Heijer, M.D., Ph.D. (Amphia Ziekenhuis); A. Pieter Kappetein, M.D., Ph.D. (Erasmus University Medical Center); Friedrich W. Mohr, M.D., Ph.D., (Herzzentrum Universitat Leipzig, Germany); Carlos Macaya, M.D. (Hospital Clinico Universitario San Carlos, Madrid, Spain); Salma Audi, M.Sc. (Boston Scientific, Natick, MA); Keith D. Dawkins, M.D. (Boston Scientific); and Katrin Leadley, M.D. (Boston Scientific).
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