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SyncAV Study: Investigation of the Efficacy of the SyncAV Fusion Pacing Algorithm on Exercise

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT03768804
Recruitment Status : Enrolling by invitation
First Posted : December 7, 2018
Last Update Posted : April 2, 2020
Information provided by (Responsible Party):
University of Oxford

Brief Summary:

In patients with weak pumping function of the heart, uncoordinated contraction of the chambers can be corrected using a cardiac resynchronization therapy ("CRT") pacemaker. These devices make patients live longer by improving how the heart pumps and reducing symptoms such as breathlessness. However, not all patients benefit from CRT and programming devices optimally can greatly influence success. Predicting the correct timings of contraction between the atria (top chambers of the heart) and the ventricles (bottom chambers), as well as between the left and right ventricles, especially when heart rate increases during exercises, is challenging.

A new approach to optimizing CRT programming has been proposed known as 'fusion-pacing'. This allows the electrical wave from the heart's own conduction system to merge or fuse with the impulse from the pacemaker in the left ventricle. The timing of the pacemaker's impulse is continuously adjusted to measurements the device makes of the hearts natural conduction. What is not clear is how effective 'fusion-pacing' is during exercise when the hearts natural conduction changes rapidly and unpredictably. We plan to investigate this by monitoring the electrocardiogram ("ECG") whilst accurately measuring exercise performance and ability during a cardiopulmonary exercise test ("CPET") on an exercise bike. We will also ask participants to rate their perceived exercise intensity to see whether fusion pacing improves ECG resynchronization, exercise performance, and patients' symptoms compared to standard programming.

Condition or disease Intervention/treatment Phase
Heart Failure, Systolic Other: SyncAV algorithm on Other: SyncAV algorithm off Not Applicable

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 22 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Intervention Model Description: Double blind, randomised crossover study
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Assessing the Effect of the SyncAV Algorithm in Cardiac Resynchronization Therapy on Exercise Capacity and QRS Duration on Exercise
Actual Study Start Date : May 31, 2019
Estimated Primary Completion Date : December 2020
Estimated Study Completion Date : December 2020

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
SyncAV algorithm on
Device randomised to have SyncAV on, with delta programmed to the value which gives the narrowest QRS duration at rest and pseudo left ventricular ("LV") only pacing
Other: SyncAV algorithm on
Cardiac Resynchronisation Device will be set to have the SyncAV algorithm on for the duration of the cardiopulmonary exercise test ("CPET"), before being reset to pre-existing settings

SyncAV algorithm off
Device randomised to have SyncAV off, with a fixed sensed atrioventricular ("AV") delay of 120ms or shorter if necessary to prevent fusion, and biventricular ("BiV") pacing
Other: SyncAV algorithm off
ardiac Resynchronisation Device will be set to have the SyncAV algorithm off and a fixed AV delay, for the duration of the CPET, before being reset to pre-existing settings

Primary Outcome Measures :
  1. Exercise capacity [ Time Frame: 1 Year ]
    Exercise capacity as measured by cardiopulmonary exercise testing ("CPET") including blood sampling

  2. BORG-RPE rating [ Time Frame: 1 Year ]
    Borg rating of perceived exertion ("Borg-RPE") during CPET

Secondary Outcome Measures :
  1. QRS duration [ Time Frame: 1 Year ]
    QRS duration during exercise, compared to at rest

  2. Exercise duration [ Time Frame: 1 Year ]
    Exercise duration as measured by cardiopulmonary exercise testing ("CPET")

  3. PR duration [ Time Frame: 1 Year ]
    Intrinsic PR duration during exercise when fusion pacing is on

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Age ≥18 and able to give informed consent.
  • Patients with existing cardiac resynchronization therapy ("CRT") devices able to utilise the SyncAV algorithm, implanted ≥6 months and under follow up at Oxford University Hospitals National Health Service ("NHS") Foundation Trust.
  • Evidence of response to CRT, defined as functional improvement or left ventricular ("LV") remodelling on imaging.
  • Sinus rhythm and PR interval <250ms.
  • Able to exercise to perform cardiopulmonary exercise testing ("CPET").

Exclusion Criteria:

  • Pregnancy or breast feeding.
  • Atrial fibrillation or atrial tachycardia.
  • Underlying 2nd or 3rd degree heart block.
  • PR interval ≥250ms.
  • Chronotropic incompetence, defined as use of rate-response algorithm or ≥80% atrial pacing.
  • Any concurrent condition contraindicating use of CPET.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03768804

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United Kingdom
Department of Physiology, Anatomy and Genetics, University of Oxford
Oxford, Oxfordshire, United Kingdom, OX1 3PT
Sponsors and Collaborators
University of Oxford
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Principal Investigator: Neil Herring, BMBCh MRCP University of Oxford
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Responsible Party: University of Oxford Identifier: NCT03768804    
Other Study ID Numbers: 13808
First Posted: December 7, 2018    Key Record Dates
Last Update Posted: April 2, 2020
Last Verified: April 2019
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Plan Description: No IPD to be shared

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Product Manufactured in and Exported from the U.S.: No
Keywords provided by University of Oxford:
Cardiac resynchronisation therapy
Fusion pacing
Additional relevant MeSH terms:
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Heart Failure, Systolic
Heart Failure
Heart Diseases
Cardiovascular Diseases