Pacemaker therapy for drug-refractory symptoms in mid-cavity HCM
Research type
Research Study
Full title
Distal ventricular pacing and intraventricular gradient reduction for symptomatic relief in drug-refractory hypertrophic cardiomyopathy patients with mid-cavity obstruction
IRAS ID
179050
Contact name
Saidi Mohiddin
Contact email
Duration of Study in the UK
3 years, 8 months, 14 days
Research summary
Research Summary
Hypertrophic cardiomyopathy (HCM) is the most common familial heart disease, affecting one in five hundred of the general population. Characterised by abnormal thickening of the heart in absence of other reasonable causes such as heart valve disease, the various patterns of thickening mean blood flow within the heart is often abnormal. Obstruction to blood flow out into the main artery, the aorta, is often present at a level below that of the aortic valve, and this can place extra strain upon the heart muscle.
This extra strain means patients frequently suffer from debilitating symptoms such as shortness of breath and chest pain, poor exercise tolerance, or dizzy spells. Around 60% of HCM patients will have obstruction to blood flow at the base of the heart, at the level of the mitral valve, and there are several invasive therapies to consider as treatment if treatment with medicine is failing to reduce symptoms. However, in a smaller group of around one in ten HCM patients, obstruction to blood flow occurs in a different area, within the middle of the left heart. These patients provide a challenge for management, as they are less suitable for invasive treatment options.
Using a pacemaker to excite the heart in patients with obstruction within the middle of the heart has been demonstrated to reduce the obstruction and importantly improve patient symptoms, and this is supported by our pilot data. The research questions to be addressed are: How effective is cardiac pacing at reducing obstruction in the middle of the heart? The second question is does this lead to symptomatic benefit for the patient?
This novel study will be conducted at Barts Heart Centre in London. Participants will be involved in the study for around 13 months.Summary of Results
We recruited a total of 17 patients with hypertrophic cardiomyopathy and mid-cavity obstruction to our study. These patients were severely symptomatic despite taking medicines. Most of them (16) underwent a personalised pacing procedure in the catheter lab at the time of cardiac pacing device implant. When we assessed the effects of using the pacemaker in the catheter lab, we found that the abnormally high pressures (obstruction) within the main pumping chamber of the heart (the left ventricle) fell when we used the pacemaker in all 16 patients. The pacemaker was able to make different parts of the left ventricle move at slightly different times, helping to reduce the high pressures within.
After the pacemaker implant procedure, patients experienced a period of the pacemaker being active all the time, and a period of it being inactive all the time, the order of which was decided at random. Of the 13 completing this follow-up period, over two thirds chose the active pacing as their preferred setting. Active pacing helped patients to walk further during a 6-minute walking test, with other secondary outcome measures also indicating benefit with pacing.
In the first randomised placebo-controlled trial of pacing in mid-cavity hypertrophic cardiomyopathy, we have shown that pacing reduces obstruction in the heart and improves exercise performance in severely symptomatic hypertrophic cardiomyopathy patients with mid-cavity obstruction.REC name
London - Harrow Research Ethics Committee
REC reference
17/LO/1725
Date of REC Opinion
1 Dec 2017
REC opinion
Further Information Favourable Opinion