Comparing angioplasty and bypass surgery for new patient groups
The two surgical methods used for angina or heart attack have primarily been studied in patient groups consisting of white men. Björn Redfors is currently involved in two international studies aiming to broaden the understanding of treatments for coronary artery stenosis.
Björn Redfors is a professor of cardiovascular research focusing on epidemiology and prevention at the University of Gothenburg and a Senior Consultant in cardiology at Sahlgrenska University Hospital. The current studies are being conducted in international collaborations and are both randomized. They will include respectively 470 patients and 1,200 patients with coronary artery disease, who will be randomly assigned one of the two established treatments for angina. The first treatment is percutaneous coronary intervention (PCI), where the coronary artery is widened using a balloon inserted by the heart through an artery from the arm or groin, with a stent placed in the vessel to keep it open. The other treatment is open coronary artery bypass surgery.
Treatment choices in heart failure
The first study, led by Sahlgrenska, investigates which of the two treatment methods works best for patients with heart failure.
"There are studies suggesting both that balloon angioplasty with PCI is equivalent to bypass surgery and that PCI is not as good as bypass, but those studies have not been randomized, so the treatment methods could not be compared robustly and reliably. In practice, balloon angioplasty is chosen more often than bypass for these patients," says Björn Redfors.
The study is conducted as a Swedish study (STICH-SWEDEHEART). Several other countries are conducting similar studies with almost identical study protocols, and data from all these studies will be compiled into an international database hosted and coordinated from Gothenburg. A nice side effect of the project is that it provides an opportunity to strengthen our infrastructure for clinical trials. The research collaboration is funded by both the Swedish Research Council and ALF. The study is linked with other ongoing or planned international studies in Canada, the United Kingdom, Denmark, the USA, the Netherlands, Germany, and Australia.
"All studies are synchronized to collect the same type of data, but each country's studies are also independent. In the end, we will combine all data into a meta-study," says Björn Redfors, continuing:
"The hope is that the combined studies will provide a dataset of 2,000 patients, which could then determine whether there is a difference in survival between the two treatment methods for people with heart failure."
For this study, the outcome measures are traditional: death, heart attack, stroke, and hospitalization for heart failure.
Women and minority populations
The second study is conducted in the USA and has received the equivalent of over 300 million SEK. The study is led jointly by principal investigators, with Björn Redfors being the only non-American researcher and the University of Gothenburg the only non-American participating university. It is a multicenter clinical trial led by the research units at Cornell University and Mount Sinai Hospital in New York. The purpose is to compare balloon angioplasty with bypass surgery for women and underrepresented minorities.
Bypass involves a higher risk during the procedure, but previous studies have shown it to have the best long-term prognosis. However, these studies mainly included white men, and the scientific basis is very limited regarding women and underrepresented minorities.
"The clinical studies that form the basis of the clinical evidence in cardiology primarily included white men. Less than 25 percent of the patients who participated in these studies were women, and minorities represented only ten percent of the patients," says Björn Redfors.
There is data suggesting that the risks of bypass are somewhat higher for women than for men. But there is also data suggesting that women have higher risks after percutaneous coronary intervention, and the scientific evidence regarding the relative effects of bypass versus PCI for women is therefore limited.
"Women generally develop stenosis and angina ten years later than men, and it is more common for men to have more extensive coronary artery disease."
Highlighting quality of life
There are several differences between women and men that could affect how well the treatment works, says Björn Redfors. Women are usually smaller and also have smaller vessels. It has also been shown that coronary artery spasm is more common in women. For minorities, there are also socioeconomic differences that can affect the outcome of the various treatments.
This study also has an outcome measure that is unusual in cardiovascular research regarding coronary artery disease: quality of life.
"Although doctors have the expert knowledge, the patient should always be included in their own care, and for them, quality of life is often a very important parameter in the informed choice. Here we will be able to give the patient a fairly good picture of what change in quality of life they can expect over time for the different treatment methods," says Björn Redfors.
By: Elin Lindström
- Balloon Angioplasty (PCI – Percutaneous Coronary Intervention) involves using a balloon, and often a thin metal mesh (a stent), to widen the heart's vessels. The material is placed using a long catheter through an artery.
- Coronary Artery Bypass Surgery (CABG – Coronary Artery Bypass Grafting) involves opening the chest, and the surgeon creates a bypass around the stenosis using a vessel taken from the patient's arm or leg.