In the first-ever, double-blinded, placebo-controlled trial, researchers tested the efficacy of heart stents in patients with stable angina.
Angina is pain or discomfort in the chest due to a lack of oxygen in the blood flowing to the heart. This pain is not limited to the chest but can spread to the back, neck, arms, or jaw. There are four types of angina and stable angina is the most common type. Stable angina results from the heart overworking. Since it has a regular pattern of occurrence, severity, and triggering factors, individuals with stable angina can often predict when pain will occur. Stable angina is not a disease by itself, but a symptom of coronary artery disease and those with stable angina are at more risk of having a heart attack in the future.
Percutaneous Coronary Intervention
Percutaneous coronary intervention (PCI) is a treatment method that uses heart stents to increase the size of the arteries of the heart. Doctors insert a catheter (a flexible tube) into the arteries of the heart and then inject dye to visualize blockages. Next, they inflate a balloon at the tip of the catheter, which expands the blood vessel and allows for more blood flow to the heart.
The common perception is that PCI improves angina. However, there had been no placebo-controlled clinical trials to support this recommendation. This is in part due to concerns regarding the ethical acceptability of exposing patients to an invasive placebo procedure. In a recent research news update, the British Medical Journal reported the first double-blinded randomized controlled trial published in The Lancet to evaluate the effectiveness of PCI in improving the exercise capacity or symptoms in patients with coronary stenosis—a narrowing of the arteries.
Evaluating the Efficacy of Heart Stents Versus a Placebo
The study took place in the United Kingdom where researchers recruited 200 participants with stable angina and coronary stenosis in only one of the three arteries of the heart, referred to as single-vessel coronary disease. For six weeks prior to the start of the trial, the participants received increasing doses of medication to treat angina. The study was double-blinded as the participants were not aware whether they had been randomly assigned to the placebo group or the treatment group, and the doctors were also unaware which group each participant belonged to. The treatment group received heart stents and the placebo group only underwent insertion of a catheter without the balloon inflation. The efficacy of the heart stents was tested by recording the duration of time participants were involved in exercise before the study and six weeks post-study.
Despite successfully expanding the arteries, which led to increased blood flow, the average exercise time increased by only 28.4 seconds and by 11.8 seconds for treatment and placebo groups respectively. These results, along with the changes in symptoms experienced in both groups were not significant.
Heart Stents May Not Be an Effective Treatment
The study was limited by the high, potentially unrealistic doses of antianginal medication given to participants prior to the study. Additionally, since the study was performed on those with single-vessel coronary disease, the results cannot be applied to those with multi-vessel coronary heart disease.
Overall, the study showed there is not necessarily a direct link between expanding the vessels of the heart and symptom relief in individuals with stable angina, and as such, heart stents may not be an effective treatment. However, lead author Rasha Al-Lamee does note that while these findings are interesting, it does not mean patients should never undergo the procedure for stable angina and those with multi-vessel coronary heart disease may get more symptom relief from heart stents.
Written by Monica Naatey-Ahumah, BSc
(1) Wise, J. (2017). Heart stents for stable angina show no benefit over placebo, study finds. BMJ, 359:j5076. https://doi.org/10.1136/bmj.j5076
(2) Al-Lamee R, Thompson D, Dehbi H, Sen, S., Tang, K., Davies, J., Keeble, T.,…Mayet, J. (2017). Percutaneous coronary intervention in stable angina (ORBITA): a double blind, randomised controlled trial. Lancet. http://dx.doi.org/10.1016/S0140-6736(17)32714-9
(3) National Heart, Lung and Blood Institute. (2016). Percutaneous Coronary Intervention. Retrieved from https://www.nhlbi.nih.gov/health/health-topics/topics/angioplasty
(4) National Heart, Lung and Blood Institute. (2011). What is Angina? Retrieved from https://www.nhlbi.nih.gov/health/health-topics/topics/angina