Biventricular Pacing After Cardiopulmonary Bypass

Study Overview
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Brief Summary
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The purpose of this study is to investigate the efficacy of optimized temporary biventricular pacing (BiVP) in patients undergoing open-heart surgery with preoperative LV dysfunction and an intraventricular conduction delay. This study will compare extended temporary biventricular pacing versus standard of care by assessing patients randomized to the two groups, from the conclusion of cardiopulmonary bypass, until the conclusion of pharmacologic circulatory support in the intensive care unit. In addition, effects of biventricular pacing will be tested in all patients, at three time points, using different measures of blood flow. Results from this research will demonstrate whether temporary BiVP improves cardiac output after open-heart surgery and whether ventricular pacing optimization increases cardiac output in this setting. Success would lead to the development of recommendations for use of BiVP postoperatively and would stimulate the development of pacemakers with appropriate features. The primary hypothesis is that the optimum pacing protocol (POPT) will increase cardiac index (CI) by 15% (from approximately 2.30 to 2.64 L/min/m2) compared to standard of care as measured by thermodilution 12-24 hours postoperatively. Secondary objectives include defining POPT at three time points within 24 hours of surgery. The investigator will examine which forms of cardiac dysfunction benefit from temporary pacing using direct and indirect measures of perfusion and cardiac function. The investigator will also analyze survival, length of stay, incidence of arrhythmias, and cost of postoperative care.

Detailed Description
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Biventricular pacing (BiVP) reverses intraventricular conduction delay (IVCD) and left ventricular (LV) dysfunction in dilated cardiomyopathy (DCM). BiVP improves LV function and cardiac index (Cl) at no energy cost. In the MIRACLE trial, in patients with DCM, IVCD and LV ejection fraction <35%, demonstrated improved subjective and objective measures of exercise tolerance and cardiac function with BiVP. BiVP benefits many, but selection criteria are not fully developed, and 30% of recipients are nonresponders, at a cost of more than $2 billion/year. Preliminary data suggest that BiVP can benefit patients with low output states after cardiac surgery. This study will assess surgical application of BiVP while assessing mechanisms of action and optimization. 190 cardiac surgery patients will be randomized with LV dysfunction preoperatively to paced and standard of care groups. BiVP will be optimized and continued postoperatively until patients are stable. BiVP will be assessed transiently in all patients at three time points. The primary end point is a 15% improvement in thermal dilution Cl measured in the intensive care unit (ICU). Effects of heart rate, atrioventricular delay, ventricular pacing site, and interventricular delay on Cl will be assessed using a randomized sequence of data collection. Secondary endpoints include incidence of arrhythmias, inotropic support, urine output, weight gain, morbidity, mortality, and ICU costs. These studies are important because of a high probability of clinical benefit. The methods employed will provide precision, breadth of measurement, and range of pacing sites superior to any other setting. The protocol will provide new and important scientific information that will benefit not only surgical patients but also the general population of BiVP recipients.

Official Title
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Biventricular Pacing After Cardiopulmonary Bypass

Conditions
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Heart Failure

Intervention / Treatment
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* Device: Optimization Testing
* Device: Temporary Biventricular Pacing


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: LV ejection fraction < 41% QRS duration > 99 msec Or: Mitral and Aortic Valve Repair or Replacement Exclusion Criteria: Congenital Heart Disease Intracardiac Shunts Preoperative Pacing for Heart Block (2nd or 3rd degree) or Sinus Bradycardia Heart Rate > 120 beats per min after Cardiopulmonary Bypass Preoperative Atrial Fibrillation Previous Cardiac Surgery Inability to undergo biventricular pacing prior to randomization

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Biventricular Pacing<br>After weaning from bypass, patients received temporary biventricular pacing for 24 hours. Values obtained from optimization testing determined pacemaker settings (AVD, VVD, heart rate). | Device: Optimization Testing<br>* Atrioventricular (AVD) and interventricular (VVD) delays and left ventricle lead site location were optimized after weaning off bypass (Phase I), after sternal closure (Phase II), and 12 to 24 hours (Phase III) after bypass. Intrinsic heart rate was also optimized in Phase III.<br>* Other names: Medtronic Insync III;Device: Temporary Biventricular Pacing<br>* Continuous temporary biventricular pacing for 24 hours at a heart rate of 90 bpm or 10 bpm above intrinsic heart rate.<br>|
| Active Comparator: Standard of Care<br>No continuous pacing occurred about surgery. Patients underwent optimization testing. | Device: Optimization Testing<br>* Atrioventricular (AVD) and interventricular (VVD) delays and left ventricle lead site location were optimized after weaning off bypass (Phase I), after sternal closure (Phase II), and 12 to 24 hours (Phase III) after bypass. Intrinsic heart rate was also optimized in Phase III.<br>* Other names: Medtronic Insync III;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Thermal Dilution Cardiac Index (CI) Measured in the Intensive Care Unit (ICU). | Cardiac output (CO) 12-24 hours after bypass is measured five times and averaged. CO is then converted to CI, after division by the patient's body surface area. | 24 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Subjects With Postoperative Complications | This is to measure the total number of subjects that experienced any of the following complications: sepsis/infection, renal failure, respiratory failure/complications, bleeding requiring reoperation, cerebrovascular accident. | 30 days after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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LV function, Compliance, wall motion, echocardiography