RecruitingNAINTERVENTIONAL

Study of Lesion-Specific Invasive Haemodynamic Angina Thresholds

This study, called ORBITA-SOLAR, wants to find out if different blockages in the heart’s blood vessels cause angina chest pain at different levels of blood flow reduction. Angina is chest pain or discomfort caused by reduced blood flow to the heart. Sixty patients experiencing stable angina who have two narrowings in their heart arteries suitable for a procedure called PCI will join. During a heart catheterisation procedure, doctors will temporarily inflate a tiny balloon inside the artery while the patient gently exercises. This helps them measure exactly how much the blood flow is reduced when angina symptoms begin, for each blockage, providing a better understanding of how these narrowings affect symptoms.

At a glance

Status

Recruiting

Phase

Sponsor

Imperial College London

Enrolment target

Start

10 Feb 2026

Estimated completion

01 Dec 2028

Angina (Stable)Ischaemic Heart Desease Coronary Artery Disease(CAD)

What is this study about?

This study is looking into a common heart condition called angina. Angina causes chest pain or discomfort because your heart isn't getting enough oxygen-rich blood, usually due to narrowed arteries. When you have angina, it often gets worse when you're active and eases when you rest.

Researchers want to understand why some narrowings in your heart's blood vessels cause more symptoms than others. They believe that not all narrowings are the same and that the 'angina threshold' – meaning how much blood flow needs to be reduced before you feel pain – might be different for each one. By understanding this better, doctors might be able to offer more personalised treatments for angina in the future.

To figure this out, the study will involve patients who have stable angina and two blockages in their heart arteries that can be treated with a procedure called PCI (Percutaneous Coronary Intervention), often known as an angioplasty and stenting. During this procedure, doctors will use special tools to carefully measure the blood flow in your arteries at the exact spot of each narrowing, while you do some gentle exercise. This will help them see precisely when your angina symptoms start in relation to how much blood flow is affected by each blockage.

Key takeaways

The study investigates how blockages in heart arteries cause angina chest pain.
It uses a heart catheterisation procedure to measure blood flow during gentle exercise.
Aims to understand why some narrowings cause more symptoms than others.
Could help lead to more personalised treatments for angina.
Involves patients with stable angina and two artery narrowings treatable by PCI.

Who may be eligible?

This study is looking for adults aged 18 or over. To be considered, you must have chest pain or similar symptoms (like breathlessness during exercise) that your doctor thinks can be improved with a heart procedure called PCI. You will also need to have two significant narrowings in your heart's main arteries, which doctors have identified through imaging tests like angiography or CT scans.

Crucially, there must be evidence that these narrowings are causing a lack of blood flow to your heart muscle (ischaemia). This might be shown by various heart tests you've already had, such as stress echocardiograms, MRI scans, or specific measurements taken during a heart catheterisation.

However, some people won't be able to join. This includes if you've had a heart attack recently (within the last three months), if you’ve previously had bypass surgery, or if you have severe issues with a main heart artery or heart valves. If you're pregnant, can't exercise, or can't give your consent, you also wouldn't be able to take part. There are also specific medical conditions or medications that would prevent you from joining, such as a severe reaction to blood-thinning medicines or to a drug often used in these tests called adenosine.

Quick self-check

Are you 18 years old or older?
Do you have stable angina symptoms that could benefit from a heart procedure (PCI)?
Do you have two narrowings in your heart arteries that doctors have identified?
Have tests shown that these narrowings are reducing blood flow to your heart muscle?
Have you NOT had a heart attack in the last three months?
Are you able to do some gentle exercise while lying down?

This is a guide only — the research team will confirm whether you can take part.

What does participation involve?

If you decide to take part, you will first have a detailed discussion with the study team to make sure it's right for you and that you understand everything involved. The main part of the study involves a heart catheterisation procedure, which is a common way doctors look at and treat heart arteries. During this procedure, a thin tube (catheter) is gently guided to your heart, and special equipment is used to measure blood flow in your narrowed arteries.

While this is happening, you will be asked to do some gentle exercise, likely on a special bike-like device, while lying down. This allows the doctors to see how your heart responds to activity and exactly when any angina symptoms might start. They will temporarily inflate a small balloon inside your artery to measure how different levels of narrowing affect your blood flow and symptoms.

After the procedure, the study team will monitor you closely. They will explain any follow-up appointments, which will likely involve checks on your recovery and overall well-being. The total duration of your active involvement in the study mostly revolves around the catheterisation procedure itself and immediate recovery, followed by short-term check-ups.

Potential risks and benefits

Taking part in this study may offer you the benefit of close monitoring and evaluation of your heart condition, which could lead to a deeper understanding of your specific angina. However, like any medical procedure, there are potential risks associated with heart catheterisation, such as bleeding or infection at the site where the catheter is inserted, or rarely, more serious complications. The study also involves inflating a balloon in your artery, which is done carefully by experienced doctors. You will have full rights to withdraw from the study at any time without giving a reason, and this will not affect the quality of your care.

Locations (6)

Mid and South Essex NHS Foundation Trust
Basildon, United Kingdom· Not yet recruiting
University Hospitals Dorset NHS Foundation Trust
Bournemouth, United Kingdom· Not yet recruiting
Imperial College Healthcare NHS Trust
London, United Kingdom· Recruiting
Royal Free London NHS Foundation Trust
London, United Kingdom· Not yet recruiting
St George's University Hospitals NHS Foundation Trust
London, United Kingdom· Not yet recruiting
Portsmouth Hospitals University NHS Trust
Portsmouth, United Kingdom· Not yet recruiting

Common questions

What is angina?

Angina is a type of chest pain or discomfort caused by reduced blood flow to the heart muscle. It often feels like squeezing, pressure, or fullness in your chest, and can spread to your arms, neck, jaw, or back.

What is PCI?

PCI stands for Percutaneous Coronary Intervention. It's a procedure to clear blocked or narrowed heart arteries, usually involving a balloon to open the artery and a small mesh tube called a stent to keep it open.

Why is this study important?

This study aims to help doctors better understand how different blockages in heart arteries cause angina symptoms. This could lead to more effective and personalised treatment plans for people with angina in the future.

Will I get 'better' taking part?

While the study focuses on understanding your condition, the information gathered might help your doctors tailor your treatment. However, the study itself is primarily for research purposes to gain new knowledge.

What does a 'heart catheterisation' involve?

It's a procedure where a thin, flexible tube (catheter) is inserted into a blood vessel, usually in your wrist or groin, and threaded up to your heart. It allows doctors to see your heart arteries and measure blood flow.

How to find out more

Kayla Chiew, MBBS MRCP

kayla.chiew@imperial.ac.uk 020 7594 5735 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.