Response to Cardiac Resynchronization Therapy of Previously Right Ventricular Paced Heart Failure Patients

Study Overview
=================
Brief Summary
-----------------
The present proposal is designed to investigate the response to CRT in patients who were previously paced from the right ventricle (RV). The negative physiologic and structural changes associated with chronic RV pacing are well documented, but patient response following upgrade to CRT after chronic RV pacing has not been well characterized in a large cohort.

Detailed Description
-----------------
The RV apex has historically been used as the site for ventricular pacing in cases of sinus node dysfunction or atrioventricular block because of its relatively accessible location for lead implantation. Initial studies showed RV pacing improved symptoms, exercise capacity, quality of life, and survival in these patients.11-13 However, more recent studies have illustrated that chronic RV pacing may actually impair LV systolic function and increase the risks of heart failure, hospitalization, and death in some patients. The primary hypothesis is that patients upgraded to CRT from a RV pacemaker respond better than those receiving CRT as a first time device. To test this hypothesis the investigators will compare changes in cardiac size and function, and hospitalization and survival rates between the two patient groups. The second hypothesis will investigate whether changes in septal dyssynchrony are correlated with changes in ejection fraction in previously RV paced patients. The investigators believe that the patients with the most improvement in septal dyssynchrony due to RV pacing will see the greatest improvement in LV function following upgrade to CRT. A significant correlation between change in IM-S and change in EF will support the hypothesis.

Official Title
-----------------
Response to Cardiac Resynchronization Therapy of Previously Right Ventricular Paced Heart Failure Patients

Conditions
-----------------
Heart Failure, Pacing Induced Dyssynchrony

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Received a CRT device between 2003 and 2009 at United Heart & Vascular Clinic QRS duration > 120 msec Pre-CRT ejection fraction =< 35% Exclusion Criteria:

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Previously RV Paced<br>Patients who were RV paced prior to receiving a cardiac resynchronization therapy device. | |
| Non-Previously RV Paced<br>Patients who received a CRT device without being previously RV paced. | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Death from any cause | Retrospectively measure the time in days from device implant to death, if applicable. | Average of 4 years | 
| Cardiovascular Hospitalization | Retrospectively measure the time in days from device implant to hospitalization, if applicable. | Average of 4 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in ejection fraction | A measure of cardiac performance. | Approximately one year | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
cardiac resynchronization therapy, heart failure, mortality