CompletedNot ApplicableInterventional

Evaluation of unloading the heart in patients with cardiogenic shock treated with mechanical circulatory support devices

Cardiogenic shock occurs when the heart suddenly cannot pump enough blood to meet the body's needs, often after a severe heart attack. In hospital intensive care units, doctors may use a life-support machine called VA-ECMO. This machine acts like a temporary heart and lung bypass to keep organs alive. However, it can push blood backward, putting harmful pressure on the recovering heart. To relieve this strain, doctors can insert an extra helper pump. Two devices are commonly used: the intra-aortic balloon pump (IABP) and the Impella pump. Currently, doctors do not know which device works better because they have never been directly compared. This UK study compares both devices by measuring blood and oxygen flow in the heart. The results will help doctors choose the most effective treatment for future patients.

At a glance

Status

Completed

Phase

Not Applicable

Sponsor

King's College London

Enrolment target

Start

09 Mar 2022

Estimated completion

01 Aug 2026

Cardiogenic shock

What is this study about?

Cardiogenic shock is a critical medical emergency. It usually happens when a heart attack severely weakens the heart muscle, leaving it unable to pump blood around the body. Without fast treatment, vital organs such as the brain and kidneys can quickly fail. Patients need immediate, specialised care in an intensive care unit.

One modern treatment is a machine called VA-ECMO. It works like an artificial heart and set of lungs, taking blood out of the body, adding oxygen, and pumping it back in. While this keeps the patient alive, pumping blood back into the body can create backward pressure against the heart. This extra workload can prevent the heart muscle from resting and healing, and may even cause fluid to back up into the lungs.

To solve this, doctors can place a small temporary device inside the body to 'unload' the heart and take away the pressure. The two most common tools are an intra-aortic balloon pump (a thin balloon that inflates and deflates with each heartbeat) and an Impella (a tiny mechanical pump that draws blood out of the heart chamber). Both are already approved and widely used, but doctors do not know which one gives the heart a better chance to recover.

The HERACLES study directly compares these two devices in patients receiving VA-ECMO. By measuring pressure and oxygen delivery inside the heart, researchers hope to discover which pump does a better job. This will help doctors provide the best possible care for people facing this life-threatening emergency in the future.

Key takeaways

Cardiogenic shock is an emergency where the heart suddenly fails to pump enough blood.
VA-ECMO life support protects the body, but it can put extra backward pressure on the heart.
This trial compares two helper pumps (IABP and Impella) to see which one best relieves this pressure.
All study procedures take place in the hospital intensive care unit with no extra visits required.
Participation is entirely voluntary and does not replace standard NHS emergency care.

Who may be eligible?

This study is for adults aged 18 and older who are in an intensive care unit with cardiogenic shock. To take part, patients must already be on a VA-ECMO life-support machine or about to start on one, and they must be scheduled for a heart catheter procedure (a test where thin tubes examine the heart's blood vessels).

Because cardiogenic shock is a sudden medical emergency, patients are often too unwell to give consent themselves. In these cases, doctors speak to close family members or follow strict legal and ethical guidelines designed to protect the patient's best interests.

Some people cannot take part. This includes patients whose heart failure happened directly after open-heart surgery, those with mechanical heart valves, and women who are pregnant. People with known blood clots inside the heart's main chamber or severe blockages in the blood vessels of their legs are also unable to join.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Aged 18 or over
Currently treated in an intensive care unit for cardiogenic shock
Receiving (or about to start) VA-ECMO life-support treatment
Scheduled for a heart catheter procedure
Have not had recent open-heart surgery
Do not have a mechanical heart valve or severe leg artery disease

Answer every question to see your result.

What does participation involve?

Because this study takes place during emergency treatment in the hospital, there are no extra appointments or visits to attend. If enrolled, a computer randomly chooses whether the patient receives the intra-aortic balloon pump or the Impella device.

Both devices are inserted during the planned heart procedure using thin tubes guided through blood vessels. While the doctor is carrying out the procedure, they will place tiny sensors into the heart's arteries to measure blood flow and oxygen levels before and after the device is turned on. These quick checks take place while the patient is already undergoing care. Afterward, the patient continues to receive standard intensive care treatment, medications, and monitoring. The helper device is removed once the medical team decides the heart has recovered enough.

Potential risks and benefits

Taking part may not provide any direct personal health benefit, as doctors do not yet know which device is superior. However, the study will provide valuable information to improve emergency heart treatments for future NHS patients. Both devices are standard tools already used in UK hospitals. The main research risk comes from the tiny sensors used to take extra measurements, which carry a very small chance (about 1 in 300) of injuring a blood vessel or the heart wall. There is also a tiny dose of extra X-ray radiation, which adds less than a 0.1% increase to lifetime cancer risk. Joining the study is completely voluntary, and deciding not to take part will not change the high standard of care provided by the hospital team.

Locations (4)

St Thomas' Hospital
Approximate
London, England
King's College Hospital
Approximate
London, England
Harefield Hospital
Approximate
Uxbridge, England
Royal Brompton Hospital
Approximate
London, England

Common questions

What is the main goal of this study?

The study aims to find out whether an intra-aortic balloon pump (IABP) or an Impella pump is better at relieving strain on the heart during life-support treatment.

Will taking part delay emergency treatment?

No. The measurements are taken during a planned heart procedure that the patient already needs, so emergency care is not delayed.

Can patients or families choose which pump is used?

No. A computer randomly selects which pump is used to ensure the study results are fair and unbiased.

Does taking part involve extra hospital visits?

No. All study procedures happen while the patient is already being treated in the intensive care unit.

What happens if a patient cannot give consent?

Because cardiogenic shock is an emergency, doctors consult family members or independent doctors according to strict legal rules to ensure the patient's rights and safety come first.

How to find out more

Saad Ezad

saad.ezad@kcl.ac.uk +44 (0)207 188 3026 Official trial record

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