Experts explain how blood flow speed and the placebo effect of stents can tackle heart disease
The speed of blood flow and the placebo effects of a heart procedure could lead to new ways of treating heart disease, say experts.
Peter Weinberg, professor of cardiovascular mechanics at Imperial College London, and Dr Rasha Al-Lamee, interventional cardiologist at Imperial College Healthcare NHS Trust, presented their research findings on cardiovascular disease at the recent Imperial College Academic Health Science Centre (AHSC) seminar.
In the video above, Professor Weinberg showcased his work which creates computer models to understand how the speed and direction of blood flow in arteries contribute to atherosclerosis. Atherosclerosis is a condition where arteries become blocked because fatty substances such as cholesterol form plaques in their walls. These plaques cause the arteries to harden and narrow, leading to a restriction of blood and oxygen supply to vital organs. This increases the risk of life-threatening problems such as heart attacks and strokes.
Professor Weinberg described how being exposed to blood flowing in different directions during each heartbeat rather than in a straight line causes some parts of the artery wall to become permeable or 'leaky'. This means substances, such as harmful types of cholesterol, can pass more quickly from the bloodstream though the inner lining and damage the wall. He also explained that cholesterol is absorbed by some arteries more than others.
Professor Weinberg and his collaborators are now trying to understand why the direction and speed of blood flow affect the leakiness of the wall. This knowledge could then be applied to develop new drugs that reduce the amount of harmful substances being absorbed by arteries of the heart.
Dr Al-Lamee discussed her work to explore the placebo effects of heart stents on patients with stable angina in the ORBITA trial.
Stable angina is a common condition in adults in which patients feel chest pain as a result of over-exertion due to restricted blood flow to the heart. It is typically caused by the build-up of fatty plaques in the arteries and a hardening of the blood vessel walls, which makes them narrower and less flexible.
Patients can manage the condition with drugs such as beta-blockers or nitro-glycerine, however, some may undergo an invasive procedure, known as angioplasty with stent or percutaneous coronary intervention (PCI). Stents are known to save lives in patients having heart attacks but for stable angina their role is less clear.
An estimated 500,000 patients around the world undergo PCI each year for stable angina, and the procedure is thought to bring substantial relief from symptoms for patients. However, since the procedure was introduced it has been unclear how much of the relief of symptoms is due to placebo effect.
Dr Al-Lamee and her team examined 200 patients with stable angina and disease in only one coronary artery, in which researchers compared the artery-widening technique stenting with a simulated procedure – where a stent was not implanted – for the first time.
Results from the trial show that the treatment effect of stents was contributed to by both a true physical effect and some placebo effect. The overall treatment effect of stents on improvement in exercise time and symptoms was smaller than the investigators had expected.
Dr Al-Lamee explained how more analysis of the data from the ORBITA will be carried out to see whether there are subgroups of patients whose angina improves more after stenting.
The seminar was the second in a series at Imperial College Healthcare NHS Trust designed to showcase the work of the AHSC, a partnership between Imperial College London and three NHS Trusts.
The next event will be on ‘New technology to treat Parkinson’s and multiple sclerosis (MS)’ and will take place at Charing Cross Hospital on Monday 16 July from 12:00.
The talk will be delivered by Dr Nir Grossman, Lecturer in Dementia Research at the College, and Professor Paul Matthews, Edmond and Lily Safra Chair and Head of Brain Sciences at the Trust.