AV Delay Optimization vs. Intrinsic Conduction in Pacemaker Patients With Long PR Intervals (AV Delay)

Evaluation of AV Delay Optimization vs. Intrinsic Conduction in Patients With Long PR Intervals Receiving Dual Chamber Pacemakers for Symptomatic Bradycardia

This is a randomized, prospective clinical trial to determine the effects of two different pacemaker atrioventricular delay (AV delay) settings on heart function in patients with dual chamber pacemakers implanted for symptomatic bradycardia with long PR intervals (delayed conduction between upper and lower chambers of the heart). The study will compare a long, fixed AV delay (standard) with an optimized AV delay for each individual using echocardiography (experimental).

Study Overview

• Status: Completed
• Conditions: Atrioventricular Block; Cardiac Arrhythmia; Sick Sinus Syndrome; Symptomatic Bradycardia
• Intervention / Treatment: Device: Long, fixed AV delay; Device: Short, optimized AV delay

Detailed Description

Cardiac pacing is the only effective treatment for symptomatic sinus node dysfunction. Most patients with preserved left ventricular function receive dual chamber pacemakers; however, right ventricular pacing can have detrimental effects on left ventricular function due to the abnormal electrical and mechanical activation pattern of the ventricles.

Many patients receiving dual chamber pacemakers for symptomatic bradycardia have prolonged intrinsic AV conduction (first degree AV block), and as a result, will receive a significant amount of ventricular pacing if programmed at physiologic AV intervals. As an alternative, many pacemakers can be programmed to minimize ventricular pacing at the expense of allowing longer AV delays. However, these long AV delays may not be physiologic and may also lead to reduced cardiac output. At present the standard of care is either to program the pacemaker at an physiologic "natural" AV delay of about 160 msec or to program the pacemaker with a long AV delay to minimize ventricular pacing.

The main scientific questions being addressed in this study are to evaluate the acute and chronic effects on cardiac output, functional status, sense of well-being, and cardiac remodeling of a long AV delay allowing for intrinsic conduction as compared to an echocardiographically optimized AV delay during dual chamber pacing.

Patients enrolled in the trial will complete a run-in period of two weeks prior to randomization in which pacemakers will be programmed with a long-fixed AV delay to allow intrinsic conduction and minimize ventricular pacing (standard). At two weeks, patients will receive a baseline echocardiogram. To determine optimal AV delay, all patients will undergo echocardiographic analysis at varying AV delays. Optimal AV delay will be defined as the AV delay associated with the largest average aortic Doppler velocity time integral (VTI). Then, patients will be randomized to either the short, optimized (experimental) or long, fixed (standard) AV delay groups. To assess functional status and sense of well-being, patients will complete a six minute walk test and Short Form-36 Medical Outcomes Study Questionnaire. Patients return to clinic for another study visit at 6 months and repeat research procedures, including baseline echocardiogram, questionnaire, and 6 minute walk test.

• Study Type: Interventional
• Enrollment (Actual): 23
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • La Jolla, California, United States, 92093
      • UCSD Sulpizio Cardiovascular Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Patient population: Individuals with 1st degree atrioventricular (AV) block who have received a dual chamber pacemaker for symptomatic bradycardia.

Inclusion Criteria:

1. Patients greater than 18 years of age
2. Patients with symptomatic sinus bradycardia
3. Patients who meet standard indications for dual chamber pacemaker implantation
4. Patients who have 1st degree AV block determined by PR interval > 200ms

Exclusion Criteria:

1. Patients with complete or high grade AV block
2. Patients who are unable to complete dual chamber pacemaker implantation for any reason
3. Patients with congestive heart failure determined by a Left Ventricular Ejection Fraction < 45%
4. Patients with persistent atrial fibrillation
5. Sustained premature ventricular contractions (PVCs), premature atrial contractions (PACs), atrial flutter, or other heart conditions that may interfere with echocardiography measurements
6. Patients who are pregnant
7. Patients with Paroxysmal Atrial Fibrillation that have had an episode(s) within 30 days of consent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Long, fixed AV delay; Pacemaker will be set to a long, fixed AV delay to minimize ventricular pacing	Device: Long, fixed AV delay; Pacemaker will be set to a long, fixed AV delay to minimize ventricular pacing
Experimental: Short, optimized AV delay; Pacemaker will be set to the AV delay that produces the greatest cardiac output in echocardiography for each patient enrolled	Device: Short, optimized AV delay; Pacemaker will be set to the AV delay that produces the greatest cardiac output in echocardiography for each patient enrolled.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Change in cardiac output determined by echocardiography	6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in functional status determined by 6 minute walk.	Measure distance walked in 6 minutes in meters.	6 months
Changes in sense of well being as determined by Short Form - 36 Medical Outcomes Study Questionnaire	Sense of well being score determined by answers to questions on Short Form - 36 questionnaire.	6 months

Collaborators and Investigators

• Sponsor: University of California, San Diego
• Investigators: Principal Investigator: Gregory K Feld, MD, UCSD Electrophysiology

Publications and helpful links

General Publications

• Sawhney NS, Waggoner AD, Garhwal S, Chawla MK, Osborn J, Faddis MN. Randomized prospective trial of atrioventricular delay programming for cardiac resynchronization therapy. Heart Rhythm. 2004 Nov;1(5):562-7. doi: 10.1016/j.hrthm.2004.07.006.
• Tops LF, Schalij MJ, Bax JJ. The effects of right ventricular apical pacing on ventricular function and dyssynchrony implications for therapy. J Am Coll Cardiol. 2009 Aug 25;54(9):764-76. doi: 10.1016/j.jacc.2009.06.006.
• Iliev II, Yamachika S, Muta K, Hayano M, Ishimatsu T, Nakao K, Komiya N, Hirata T, Ueyama C, Yano K. Preserving normal ventricular activation versus atrioventricular delay optimization during pacing: the role of intrinsic atrioventricular conduction and pacing rate. Pacing Clin Electrophysiol. 2000 Jan;23(1):74-83. doi: 10.1111/j.1540-8159.2000.tb00652.x.
• Sweeney MO, Ellenbogen KA, Tang AS, Whellan D, Mortensen PT, Giraldi F, Sandler DA, Sherfesee L, Sheldon T; Managed Ventricular Pacing Versus VVI 40 Pacing Trial Investigators. Atrial pacing or ventricular backup-only pacing in implantable cardioverter-defibrillator patients. Heart Rhythm. 2010 Nov;7(11):1552-60. doi: 10.1016/j.hrthm.2010.05.038. Epub 2010 Jun 4.

Study record dates

Study Major Dates

• Study Start (Actual): June 1, 2013
• Primary Completion (Actual): December 31, 2021
• Study Completion (Actual): December 31, 2021

Study Registration Dates

• First Submitted: May 28, 2014
• First Submitted That Met QC Criteria: May 30, 2014
• First Posted (Estimate): June 3, 2014

Study Record Updates

• Last Update Posted (Actual): May 24, 2022
• Last Update Submitted That Met QC Criteria: May 20, 2022
• Last Verified: May 1, 2022

More Information

Terms related to this study

• Keywords: Arrhythmia; Echocardiography; Pacemaker; Bradycardia; Atrioventricular block; Sick Sinus Syndrome; Atrioventricular delay; AV delay; PR interval; AV block; AV optimization
• Additional Relevant MeSH Terms: Pathologic Processes; Heart Diseases; Cardiovascular Diseases; Cardiac Conduction System Disease; Arrhythmia, Sinus; Heart Block; Bradycardia; Arrhythmias, Cardiac; Sick Sinus Syndrome; Atrioventricular Block
• Other Study ID Numbers: 130663

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes