Pacemaker trial aims to beat heart failure

Guy’s and St Thomas’ is trialling new technology that for the first time helps position pacemaker leads in the most effective areas for patients with heart failure.

The trial could see improved outcomes for the 46,000 people a year in the UK who have pacemakers fitted. Around three million have pacemakers worldwide.

The study centres on Cardiac Resynchronisation Therapy (CRT), which is a common procedure offered to patients whose heart is not beating normally due to uncontrolled electrical activity. This means the organ struggles to circulate blood and oxygen around the body, leading to patients straining with everyday tasks causing tiredness, breathlessness and even fainting.

A special type of pacemaker is fitted to ensure the contraction between the two chambers of the heart is synchronised to make it beat more effectively.

Most pacemakers have one or two wires to the heart, but CRT requires an extra wire that is more challenging to fit than the other wires. This additional lead is inserted into the main left ventricle of the heart.

It is critical that the lead is placed in the best position and avoids scar tissue, which is tissue damaged by a heart attack. The electrical pulse from the pacemaker’s lead is significantly less effective in scar tissue with studies showing that up to one third of patients may not respond to treatment due to the lead being placed there.

Under the trial, doctors will use MRI scans which are layered on top of an X-ray in real time which allows cardiologists to quickly and easily calculate the best position for the lead.

The trial is testing prototype software called the Guide CRT platform developed in a partnership between Guy’s and St Thomas’ Department of Cardiology, biomedical engineers at King’s College London and Siemens Healthineers.

The randomised study, called Tactic CRT, is taking place at a state-of-the-art catheter laboratory in St Thomas’ Hospital.

During the study, which is expected to last two years, half of patients will have pacemakers fitted using the MRI guidance and the other half will not in order to assess whether MRI guidance improves outcomes.

Aldo Rinaldi, consultant cardiologist and professor of cardiac electrophysiology at Guy’s and St Thomas’ and King’s College London, said: “This is a very exciting trial as it could radically improve the lives of people with heart failure.

“For the first time we are able to accurately position a pacemaker in the heart which means we can avoid scar tissue in people with heart failure. The reason this is so important is that scar tissue is damaged tissue caused by heart attacks and this is less effective in conducting the electrical pulse from the pacemaker.

“This combination of imaging technologies means we can identify exactly where we want the pacemaker leads to be in order to maximise the electrical charge they carry in order to properly re-synchronise the heart.”

The first patient on the study was 68-year-old David Butler from the Isle of Sheppey who has had four heart attacks and has been suffering with severe breathlessness.

In April this year he had a heart attack and was transferred to Guy’s and St Thomas’ where he was offered the chance to be on the Tactic CRT study.

David said: “I used to get tired very easily and was generally not well. I couldn’t walk very far before I would become short of breath and even having a shower and drying would be exhausting.

“When the cardiologist said there was this new pacemaker that could help and asked if I wanted to take part in the trial I said yes. I had the operation on the Friday and the next day I woke up and said ‘Wow, I feel great!’”

“Each day I feel better and better and last week I was on a building site and had to climb five sets of stairs and I was able to do it while younger people with me were tired.

“I have five granddaughters aged 1 to 18 years old. My aim is to live long enough to see them get married. I can’t praise the cardiology team and the nursing staff at St Thomas’ enough. They were fantastic.”

As well as being trialled at Guy's and St Thomas', the software was developed at the Trust. Guy's and St Thomas' clinicians in partnership with imaging researchers at King's College London and Siemens have developed a novel MRI guidance system to identify the best place for the electrodes. The research was supported by the NIHR Guy's and St Thomas' Biomedical Research Centre and Siemens.