What is the role of arrhythmias in heart failure? RHYTHM-HF
Research type
Research Study
Full title
How do arrhythmias and conduction disturbances contribute to death or rehospitalisation in patients discharged following an admission with acute heart failure? A prospective, observational, multi-centre cohort-study conducted over 4 years.
IRAS ID
197603
Contact name
Roy Gardner
Contact email
Sponsor organisation
NHS National Waiting Times Centre
Duration of Study in the UK
4 years, 2 months, 31 days
Research summary
Summary of Research
We are investigating why people with heart failure (HF) are admitted to hospital and die, focussing on the role of abnormal heart rhythms ('arrhythmias') in these events. Knowledge regarding arrhythmias is limited because i) they can be short-lived and ii) until recently it was not possible to continuously monitor patients for arrhythmias over long periods of time (most of our knowledge comes from ‘snapshot’ heart rhythm recordings taken only at a single instant, or over a few days).Injectable cardiac monitors (ICMs) are very small devices that are placed under a person's skin, and can monitor for arrhythmias over months or years. We will ask up to 500 people who are in hospital due to HF to have an ICM, and then follow them for at least two years. During follow-up, their ICM will monitor for heart information, and transmit this to our database. We will also phone them every 3 months. When follow-up is complete, we will determine whether ICM-recorded arrhythmias are associated with rehospitalisations and deaths in these patients. Demonstrating this would suggest that new treatments (both medication- and device-based) should be tested to prevent these rehospitalisations and deaths.
Patients may be invited to take part in optional sub-studies, if willing. i) Magnetic resonance imaging (MRI) scan of the heart. ii) Urine and blood samples for research tests (and storage) looking for new blood and urine markers to help predict which HF patients are at highest risk of rehospitalisation or death. iii) Patients will be invited to consent to a post-mortem examination in the event they die during the study. This would help establish why people with HF die, and might suggest new treatments to prevent similar deaths in other patients.
Summary of Results
We are still in the process of analysing and publishing our final data but have produced novel information relating to mechanisms by people with heart failure can die. This is the first study ever to have systematically collected data in relation to both the cardiac electrical rhythm at time of death (using data from injectable cardiac monitors [ICMs]) and also the pathological cause of death as determined by autopsy examination.We retrieved the ICM-derived terminal cardiac rhythm in 61 patients, and have analysed these rhythm data across several hundred ICM-derived EGMs (electrograms, which are heart rhythm recordings) preceding and at the time of death across this patient cohort, allowing us to produce an unique observational description of the progressive changes in heart rhythm in patients with heart failure at the end of life.
Second, we have analysed these heart rhythms according to mode in which these patients died (such as whether the death with a sudden ‘unexpected’ death, or an anticipated death due to progressive heart failure). Describing terminal heart rhythms systemically according to cause of death is in of itself novel, but of particular interest is our finding that ~50% of “sudden cardiac deaths” were associated with a terminal cardiac rhythm that was not a tachyarrhythmia (a heart rhythm which is abnormally fast). This is important because of the conventional assumption that tachyarrhythmias are the cardinal cause of sudden cardiac death in HF, and the only target by which implantable cardioverter defibrillators (ICDs, which are implanted devices that can shock the heart) act to avert sudden death.
Further, when we combined our terminal cardiac rhythm data with our autopsy data, we produced another novel finding with regard to patients with heart failure who die suddenly. In such patients, autopsies may either identify a clear pathological cause of sudden death (such as a heart attack or a stroke), or not. In sudden deaths where there is no pathological cause identified, international guidelines recommend that the cause should be attributed to a tachyarrhythmia. In contrast to this assumption, in some patients with sudden death and no causative pathology at autopsy, we found that their terminal cardiac rhythm had been a bradyarrhythmia (an abnormally slow heart rhythm). This is a novel finding.
Whilst the results above relate to findings across our patient population when studied at a systematic level, we also gained some mechanistic evidence about how patients die from particular individual cases. For example, several of our patients who died suddenly were discovered to have suffered fatal blood clots in the lungs (pulmonary emboli) and in each case their final cardiac rhythm was different, adding to our understanding of how such patients die.
REC name
West of Scotland REC 1
REC reference
17/WS/0073
Date of REC Opinion
15 May 2017
REC opinion
Further Information Favourable Opinion