Rhythm or rate control in CRT: the RHYTHMIC study

  • Research type

    Research Study

  • Full title

    Rhythm or rate control in CRT: the RHYTHMIC study



  • Contact name

    Aldo Rinaldi

  • Contact email


  • Sponsor organisation

    Guy's and St Thomas' Foundation NHS Trust

  • Clinicaltrials.gov Identifier


  • Clinicaltrials.gov Identifier

    864055, ERC Grant Agreement Number; RG/20/4/34803 , BHF Programme Grant Number

  • Duration of Study in the UK

    3 years, 0 months, 1 days

  • Research summary

    Cardiac resynchronisation therapy (CRT) is a complex pacemaker device used to treat select patients with severe symptomatic heart failure and has been shown to improve symptoms and reduce the risk of death. Patients with atrial fibrillation (AF) do not respond as well to CRT as those in normal (sinus) rhythm as they often have fast, irregular rhythms which interrupt the pacing delivered by the CRT device. Studies have shown that the CRT device should pace at least 98% of the time (known as biventricular pacing percentage) to achieve the most benefit. There are two main options available to patients with a CRT device who have a low biventricular pacing percentage caused by AF despite taking appropriate medications. Atrioventricular (AV) node ablation involves using a catheter to ‘burn’ the AV node, which is the main electrical connection between the atria (top chambers) and ventricles (bottom chambers) of the heart. The patient remains in AF but the irregular rhythm in the atria cannot be transmitted down to the ventricles. AF catheter ablation involves using a catheter to ‘burn’ or ‘freeze’ parts of the left atrium to prevent atrial fibrillation and convert the patient back to a normal (sinus) rhythm. Currently we do not know which treatment option is best for patient with AF who have a CRT device. This study will directly compare these two interventions with the aim of determining which one is better at improving patients’ response to CRT.

    Patients who have an existing CRT device and a low biventricular pacing percentage caused by AF will be recruited at Guys and St Thomas' NHS Foundation Trust (GSTT). They will be randomised to either AF catheter ablation or AV node ablation and will be followed up at 6 months to determine which intervention is superior.

  • REC name

    London - Chelsea Research Ethics Committee

  • REC reference


  • Date of REC Opinion

    24 Feb 2021

  • REC opinion

    Further Information Favourable Opinion

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