Can a simple blood pressure test be used to improve pacemaker settings?
The clinical question
Heart failure happens when the heart becomes less effective at pumping blood around the body. In some people with heart failure, the left and right sides of the heart don’t beat in time with each other. This can make symptoms – such as breathlessness - worse. Many people experiencing this are given a treatment called ‘cardiac resynchronisation therapy’ (CRT). This involves having a special type of pacemaker implanted in the chest.
CRT works in the same way as a normal pacemaker in controlling the heartbeat. But it also sends small electrical impulses to the left and right sides of the heart to help them beat together properly. The settings on CRT pacemakers can be adjusted to help give the maximum benefit to patients. The correct adjustments to make can be worked out from an echocardiogram scan of the heart. But performing and interpreting echocardiograms do to this is time-consuming, so this is not currently done for all CRT patients.
Professor Darrel Francis and his team at Imperial College London had previously developed a new way to adjust CRT settings. This is based on simply measuring blood pressure using a sensor attached to a finger. In the BHF-funded ‘British Randomized Controlled Trial of AV and VV Optimization’ (BRAVO) study, they compared optimising CRT settings using the blood pressure measurement with the standard scan-based method. They aimed to see if their new simpler method could be used to help improve the symptoms of heart failure.
What did the study involve?
Between 2010 and 2015, the BRAVO trial recruited 401 people with heart failure. The participants had been fitted with a CRT pacemaker at least 6 months previously. They were randomised to either:
- Have a scan of their heart to optimise their pacemaker settings.
- Have their pacemaker settings optimised using the finger blood pressure method.
The patients then returned 6 months later to assess how well their symptoms were being controlled. This involved:
- A scan of their heart.
- Answering a questionnaire about their quality of life.
- Having their blood tested for levels of a molecule which can indicate how well the heart is working.
The participants were then swapped to the alternative optimisation method, and returned after a further 6 months for the same tests.
What did the study show?
The study showed that the blood pressure-based method of adjusting CRT pacemaker settings was just as good as the scan-based method. The blood pressure method is also much less time consuming and, given how simple it is, can provide an improved experience for patients.
Why is the study important?
The results of BRAVO suggest that blood pressure-based method is an acceptable alternative way to help give each patient the best possible improvement in their symptoms. The investigators could take and analyse the blood pressure measurements in about 15-20 minutes. But they believe this process could be automated to speed it up even more. This new optimisation method has been incorporated into a non-invasive blood pressure monitor, and is now available worldwide.
Dr Zachary Whinnett, who co-led BRAVO, is now leading another BHF-funded trial, the HOPE-HF trial. This trial is testing a special type of pacemaker therapy, called ‘His bundle pacing’, alongside the blood pressure method for identifying the best pacemaker settings. He said: “In HOPE-HF, we are investigating whether a new form of pacemaker treatment can help people with heart failure, who are not eligible for traditional CRT. With His bundle pacing we stimulate the main pumping chambers of the heart to contract using the heart’s very efficient natural electrical conduction system."
Study details
"British Randomised controlled trial of AV and VV Optimisation (BRAVO): randomised clinical trial of effects of non-invasive haemodynamic optimisation of cardiac resynchronisation devices on exercise capacity"
Award reference: SP/10/002/28189
Principal Investigator: Professor Darrel Francis, Imperial College London
Trial registration number: NCT01258829
Publication details
Whinnett ZI, Sohaib SMA, Mason M, et al. Multicenter Randomized Controlled Crossover Trial Comparing Hemodynamic Optimization Against Echocardiographic Optimization of AV and VV Delay of Cardiac Resynchronization Therapy: The BRAVO Trial. JACC Cardiovasc Imaging. 2019;12(8 Pt 1):1407-1416.