Funded by £1.8m from the British Heart Foundation (BHF), the device is used to shock the heart if it goes into cardiac arrest.
Over 2,500 patients are due to be recruited across the UK for the trial in the next three years.
Phil O'Donoghue, 53, was the first patient to be implanted with the new technology. He suffers from non-ischemic cardiomyopathy (NICM), a common type of heart failure which can lead to abnormal heart rhythms, and sudden cardiac arrests are a possible cause of death in these patients.
After being diagnosed with a heart condition during the first Covid-19 lockdown in May 2020, he said the diagnosis had a big effect on his day-to-day life.
"I can't do the things I want to do if it means exerting myself," he added. "I had to change what I did at physically at work."
O'Donoghue was on medication for two-and-a-half years but then suffered further episodes in January this year and then again in March.
"I was rushed into hospital and tests showed my heart's ejection rate was down to 24 per cent, which meant blood was not being pumped around my body properly. I was told there was a trial about to start and that I fitted what they were looking for."
Heart failure effects over 900,000 people in the UK, with around 200,000 new cases diagnosed each year at an estimated cost of £2bn to the NHS.
Phil O'Donoghue during the surgery
Image credit: Southampton Clinical Trials Unit
Image credit: Southampton Clinical Trials Unit
Implantable cardioverter defibrillators (ICDs) are small devices that are routinely fitted in the chests of patients with heart failure. They can stop abnormal rhythms and treat cardiac arrest by delivering an electric shock to the heart.
"The current guidelines look at how well the heart is pumping to decide which patients should get a defibrillator," said Dr Andrew Flett, chief investigator on the trial. "But for many patients who go through the procedure of having a defibrillator fitted, they will never actually see the device triggered and may not need it. We therefore want to find a better way to assess which patients will truly benefit from one of these devices.
"There is evidence that scar tissue in the heart muscle may be the cause of dangerous heart rhythms for patients with NICM. This will be the first ever trial to look at whether the presence of scar tissue can predict who should be fitted with an ICD."
An MRI scan is used to detect the presence of scar tissue in the heart and those patients are invited into the trial.
The trial is currently open to patients at five hospitals in Southampton, Portsmouth, Aberdeen, East Kent and Barts in London, with a further 30 sites to open in the coming months.
Professor Sir Nilesh Samani, medical director of the BHF, said: "ICDs are crucial devices to treat sudden cardiac arrest and save lives. But it is important that we continue to establish exactly which patients need them, so that people who are unlikely to benefit do not have to undergo invasive procedures unnecessarily.
"The British trial will test whether the presence of scar tissue in the heart predicts who will benefit most from having an ICD."
