Can ‘preconditioning’ the heart improve outcomes after cardiac surgery?
The clinical question
Coronary heart disease (CHD) happens when the arteries supplying the heart become narrowed by a gradual build-up of fatty material within their walls. Many people with CHD are treated with coronary artery bypass grafting (CABG). Here, surgeons use pieces of a vein or an artery to bypass narrowed sections of the coronary arteries. This helps to restore normal blood flow to the heart muscle.
But CABG is not without risk. Quickly restoring blood flow to the heart can unexpectedly damage heart muscle. This process is called ‘ischaemia-reperfusion injury’. There is some evidence that the heart and other organs can be protected against this injury by ‘remote ischaemic conditioning’. Here, blood flow to the arm or leg is repeatedly restricted and restored again using a blood pressure cuff.
The BHF and the MRC/NIHR co-funded the ‘Effect of Remote Ischaemic preConditioning on Clinical outcomes in patients undergoing Coronary Artery bypass graft surgery’ (ERICCA) trial led by Professor Derek Hausenloy at University College London. The team aimed to test whether remote ischaemic preconditioning before CABG could improve clinical outcomes.
What did the study involve?
Between 2011 and 2014, the trial enrolled 1612 people undergoing CABG. Participants were recruited across 30 UK hospitals, and were randomly assigned to:
- Receive remote ischaemic preconditioning before their surgery. This consisted of four 5-minute inflations and deflations of a standard blood-pressure cuff on their upper arm.
- Receive ‘sham conditioning’. This was the same number of cycles, but with the cuff valve open, meaning it did not actually inflate.
Participants were followed up for 1 year following their surgery. The team recorded:
- Whether they experienced heart and circulatory complications, such as a heart attack or stroke.
- Whether they experienced kidney injury after their surgery, a possible side effect of heart surgery.
- Their duration of stay in the intensive care unit and hospital.
- The distance they could cover on the 6-minute walk test.
- The results of questionnaires about their quality of life.
What did the study show?
The study did not show any evidence of protection after remote ischaemic preconditioning. Heart and circulatory complications, duration of stay in the intensive care unit and hospital, quality of life and all the other outcomes studied were similar with or without the preconditioning in CABG patients.
Why is the study important?
The ERICCA trial was the first large randomised clinical trial to test whether remote ischaemic preconditioning affected long term clinical outcomes in CABG patients. It was important to perform this trial given previous promising results from studies in animals and smaller clinical trials.
When the results of the ERICCA trial were reported in 2015, Professor Hausenloy reflected on the findings:
“Other medications such as volatile anaesthetics, nitrates, and propofol can interfere with the protective effect of remote ischaemic preconditioning, and a significant proportion of study patients were receiving these.”
He suggested that the results of ERICCA did not mean that this technique would be ineffective in other group of patients.
Study details
"Effect of Remote Ischaemic preConditioning on Clinical outcomes in patients undergoing Coronary Artery bypass graft surgery (ERICCA study): a multicentre double-blind randomised controlled clinical trial"
Award reference: SP/10/8/28715
Principal Investigator: Professor Derek Hausenloy, University College London
Trial registration number: NCT01247545
Publication details
Hausenloy DJ, Candilio L, Evans R, et al. Remote Ischemic Preconditioning and Outcomes of Cardiac Surgery. N Engl J Med. 2015;373(15):1408-17.