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

Study Results

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Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

NA

Total Enrollment

23 participants

Study Classification

INTERVENTIONAL

Study Start Date

2013-06-01

Study Completion Date

2021-12-31

Brief Summary

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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).

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Detailed Description

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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.

Conditions

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Atrioventricular Block Sick Sinus Syndrome Symptomatic Bradycardia Cardiac Arrhythmia

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

SINGLE

Participants

Study Groups

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Long, fixed AV delay

Pacemaker will be set to a long, fixed AV delay to minimize ventricular pacing

Group Type ACTIVE_COMPARATOR

Long, fixed AV delay

Intervention Type DEVICE

Pacemaker will be set to a long, fixed AV delay to minimize ventricular pacing

Short, optimized AV delay

Pacemaker will be set to the AV delay that produces the greatest cardiac output in echocardiography for each patient enrolled

Group Type EXPERIMENTAL

Short, optimized AV delay

Intervention Type DEVICE

Pacemaker will be set to the AV delay that produces the greatest cardiac output in echocardiography for each patient enrolled.

Interventions

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Long, fixed AV delay

Pacemaker will be set to a long, fixed AV delay to minimize ventricular pacing

Intervention Type 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.

Intervention Type DEVICE

Eligibility Criteria

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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

Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No