Biventricular Versus Right Ventricular Pacing in Heart Failure Patients With Atrioventricular Block (BLOCK HF)

Study Overview
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Brief Summary
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Heart failure is a progressive disease that decreases the pumping action of the heart. This may cause a backup of fluid in the heart and may result in heart beat changes. When there are changes in the heartbeat, sometimes a pacemaker is used to control the rate and rhythm of the heartbeat. In this trial, the researchers will test if pacing both the left and right lower half of the heart (ventricles) will: decrease the number of hospital and clinic visits due to heart failure symptoms extend life delay heart failure symptoms as compared to those who are paced in only one ventricle (the right ventricle)

Official Title
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Biventricular Versus Right Ventricular Pacing in Heart Failure Patients With Atrioventricular Block (BLOCK HF)

Conditions
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Atrioventricular Block, Heart Diseases

Intervention / Treatment
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* Device: Cardiac Resynchronization Therapy (CRT)
* Device: Cardiac Resynchronization Therapy (CRT)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subject has standard class I or class IIa indication for pacemaker implantation in accordance with ACC/AHA/HRS guidelines Subjects diagnosed with atrioventricular (AV) block. An AV block is a disturbance when the heart's natural pacemaker sends a message from the atrium (top part of heart) to the ventricle (bottom part of heart) and the message is partially or totally blocked Subject is receiving first time implant Subjects with heart failure but no symptoms of it (New York Heart Association [NYHA] Class I), or subjects with mild heart failure that only sometimes interferes with their daily activities (NYHA Class II), or subjects with heart failure that severely limits daily activities (NYHA Class III) Subjects with documented reduced heart pumping function (left ventricular ejection fraction ≤ 50%) within past 90 days Subject is at least 18 years old Subject or authorized legal guardian or representative has signed and dated the Informed Consent Subject is able to receive a pectoral implant Subject is expected to remain available for follow-up visits at the study center Subject is willing and able to comply with the protocol Exclusion Criteria: Subject has ever had a previous or has an existing device implant Subjects with some forms of chest pain or myocardial infarction (heart attack) within the past 30 days Subjects with coronary bypass within the past 30 days Subjects with stent within the past 30 days Subjects with valve repair or replacement within the past 6 months or is indicated for repair or replacement Subjects with a mechanical right heart valve Subject is indicated for a biventricular pacing device (CRT-P or CRT-D devices) Subject is enrolled in a concurrent study which may confound the results of this study (co-enrollment in any concurrent clinical study requires approval of the study manager) Subject is pregnant, or of child bearing potential and not on a reliable form of birth control Subjects with a previous heart transplant Subjects has been classified as NHYA Functional Class IV within prior 90 days (subjects with severe heart failure and should always be resting) Subject, legal guardian or authorized representative is unable or unwilling to cooperate or give written informed consent

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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Biventricular pacing<br> | Device: Cardiac Resynchronization Therapy (CRT)<br>* Biventricular pacing<br>* Other names: Medtronic CRT-D;|
| Active Comparator: Right ventricular pacing<br> | Device: Cardiac Resynchronization Therapy (CRT)<br>* Right ventricular pacing<br>* Other names: Medtronic CRT-D;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mortality, Heart Failure-related Urgent Care Visits, or Significant Increase in Left Ventricular End Systolic Volume Index (LVESVI) | Events include all-cause mortality, heart failure(HF)-related urgent care (a healthcare utilization visit involving intravenous(IV) therapy for heart failure) or significant increase(at least 15%) in LVESVI (a measure of the volume of a patient's left ventricle) from randomization to a later time point. Time from randomization until the subject experienced one of these events served as the outcome measure. LVESVI endpoints occurred primarily at those visits in which LVESVI measurements were required (6, 12, 18, 24 months). Because endpoints such as death or HF urgent care could occur at any time during follow-up, the subject's outcome measure could range from less than 1 month to 105 months (maximum follow-up duration). Primary endpoints and follow-up data occurring after a subject missed a required LVESVI measurement were excluded from the analysis and the table below. The counts reflect the number of subjects meeting each endpoint, and are not necessarily mutually exclusive. | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| All-Cause Mortality | The endpoint is the time to death from any cause. The rate of mortality, as measure by the hazard rate, in each randomization arm will be compared. This outcome includes all post-randomization deaths, whereas the reporting of the primary outcome excluded primary endpoints (including deaths) that occurred after the subject had missed a study-required echocardiogram (used to determine if the LVESVI primary endpoint was met). | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| All-Cause Mortality or Heart Failure-related Hospitalization | The endpoint will be a subject's time from randomization to either their first heart failure-related hospitalization, or death. | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| All-Cause Mortality or Significant Increase in Left Ventricular End Systolic Volume Index | The endpoint will be the time from randomization to either death or a visit (6, 12, 18, 24 month or interim visit) in which the subject undergoes an echocardiogram and the measured left ventricular end systolic volume index (a measure of the size of the subject's left ventricle normalized over their body surface area) is at least 15% greater than the corresponding measured value at randomization. Only LVESVI endpoints/deaths and follow-up data occurring before a subject missed an LVESVI measurement (due to missed visit, echo not performed, etc.) were used in the analysis and included in the table below. The counts reflect the number of subjects meeting each endpoint, and are not mutually exclusive. | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| First Heart Failure Hospitalization | The endpoint is the time from randomization to a subject's first heart failure (HF)-related hospitalization. For each randomization arm, the number of subjects who met the endpoint, experiencing at least one heart failure-related hospitalization post-randomization, are reported, as well as the number of randomized subjects who did not experience any HF hospitalizations post-randomization. | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| Days Hospitalized for Heart Failure | For each subject the endpoint was the days hospitalized for heart failure per patient year, calculated as the total number of days the subject was hospitalized for heart failure divided by the subject's total follow-up time. Only post-randomization data were used. | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| Change in New York Heart Association Classification | The endpoint is a subject's change in New York Heart Association Classification (a measure of the degree of heart failure a subject has on a 4 class scale, with NYHA I being the healthiest score and NYHA IV being the sickest score) from randomization to each of four time points: 6 months, 12 months, 18 months, and 24 months post-randomization. The change categories listed will be relative to randomization. | Randomization to 24 Months | 
| Change in Heart Failure Stage | The endpoint is a subject's change in Heart Failure Stage (a measure of the degree of heart failure a subject has on a 4 stage scale (A, B, C, D), with Class A being the healthiest score and Class D being the sickest score) from randomization to each of four time points: 6 months, 12 months, 18 months, and 24 months. | Randomization to 24 Months | 
| Change in Cardiovascular Medications | The endpoints are what classes of drugs (e.g. Beta blockers, Diuretics, Nitrates, etc.) each subject was on at the time of scheduled visits (e.g Randomization, 6 months, 12 months, etc.) | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| Frequency of Adverse Events Post-randomization | Adverse events that subjects experienced after they were randomized were compared between arms with regard to several categories such as heart failure (HF)-relatedness, relatedness to the implant procedure, and relatedness to the implanted system, including individual components such as the left ventricular (LV) lead and the CRT-P or CRT-D generator. | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| Cardiovascular-related Healthcare Utilizations | Cardiovascular-related healthcare utilizations (HCUs), such as hospitalizations, Emergency Department visits, urgent care visits, and clinic visits that subjects experienced after being randomized were summarized for each randomization arm | Participants were followed for the duration of the study, an average of 39.8 months post-randomization. | 
| Change in Quality of Life at 6 Months | The endpoint will be a subject's change in Quality of Life score from randomization to 6 months. The Quality of Life score at a time point is calculated using the Minnesota Living with Heart Failure Questionnaire, which consists of 21 questions each on a 6 point scale from 0 to 5. The 21 scores are added up and the final score, ranging from 0 (best) to 105 (worst) is the subject's quality of life score. For each subject the measure will be the randomization visit - 6 month difference in QOL score, with positive values denoting a reduction in score and improvement in Quality of Life. Subjects with missing QOL scores at one or both time points were excluded from analysis, and so the number of subjects analyzed for this outcome was a subset of the number of randomized subjects. | Randomization to 6 Months | 
| Change in Quality of Life at 12 Months | The endpoint will be a subject's change in Quality of Life score from randomization to 12 months. The Quality of Life score at a time point is calculated using the Minnesota Living with Heart Failure Questionnaire, which consists of 21 questions each on a 6 point scale from 0 to 5. The 21 scores are added up and the final score, ranging from 0 (best) to 105 (worst) is the subject's quality of life score. For each subject the measure will be the randomization visit - 12 month difference in QOL score, with positive values denoting a reduction in score and improvement in Quality of Life. Subjects with missing QOL scores at one or both time points were excluded from analysis, and so the number of subjects analyzed for this outcome was a subset of the number of randomized subjects. | Randomization to 12 months | 
| Change in Quality of Life at 18 Months | The endpoint will be a subject's change in Quality of Life score from randomization to 18 months. The Quality of Life score at a time point is calculated using the Minnesota Living with Heart Failure Questionnaire, which consists of 21 questions each on a 6 point scale from 0 to 5. The 21 scores are added up and the final score, ranging from 0 (best) to 105 (worst) is the subject's quality of life score. For each subject the measure will be the randomization visit - 18 month difference in QOL score, with positive values denoting a reduction in score and improvement in Quality of Life. Subjects with missing QOL scores at one or both time points were excluded from analysis, and so the number of subjects analyzed for this outcome was a subset of the number of randomized subjects. | Randomization to 18 Months | 
| Change in Quality of Life at 24 Months | The endpoint will be a subject's change in Quality of Life score from randomization to 24 months. The Quality of Life score at a time point is calculated using the Minnesota Living with Heart Failure Questionnaire, which consists of 21 questions each on a 6 point scale from 0 to 5. The 21 scores are added up and the final score, ranging from 0 (best) to 105 (worst) is the subject's quality of life score. For each subject the measure will be the randomization visit - 24 month difference in QOL score, with positive values denoting a reduction in score and improvement in Quality of Life. Subjects with missing QOL scores at one or both time points were excluded from analysis, and so the number of subjects analyzed for this outcome was a subset of the number of randomized subjects. | Randomization to 24 Months | 
| Change in Left Ventricular Ejection Fraction (LVEF) From Randomization to 6 Months | The endpoint will be a subject's change in LV Ejection Fraction (a measure of the percentage of blood ejected from the left ventricle of the heart with each contraction). A normal range is 55% to 70%. For each subject the measure will be the 6 month - randomization visit difference in LVEF value. | Randomization to 6 Months | 
| Change in Left Ventricular Ejection Fraction (LVEF) From Randomization to 12 Months | The endpoint will be a subject's change in LV Ejection Fraction (a measure of the percentage of blood ejected from the left ventricle of the heart with each contraction). A normal range is 55% to 70%. For each subject the measure will be the 12 month - randomization visit difference in LVEF value. | Randomization to 12 Months | 
| Change in Left Ventricular Ejection Fraction (LVEF) From Randomization to 18 Months | The endpoint will be a subject's change in LV Ejection Fraction (a measure of the percentage of blood ejected from the left ventricle of the heart with each contraction). A normal range is 55% to 70%. For each subject the measure will be the 18 month - randomization visit difference in LVEF value. | Randomization to 18 Months | 
| Change in Left Ventricular Ejection Fraction (LVEF) From Randomization to 24 Months | The endpoint will be a subject's change in LV Ejection Fraction (a measure of the percentage of blood ejected from the left ventricle of the heart with each contraction). A normal range is 55% to 70%. For each subject the measure will be the 24 month - randomization visit difference in LVEF value. | Randomization to 24 Months | 
| Change in Left Ventricular End Systolic Volume Index (LVESVI) From Randomization to 6 Months | The endpoint will be a subject's change in Left Ventricular End Systolic Volume Index (a measure of the volume of blood in the left ventricle at the end of systole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 6 month - randomization visit difference in LVESVI. Negative values correspond to reductions in LVESVI over time. | Randomization to 6 Months | 
| Change in Left Ventricular End Systolic Volume Index (LVESVI) From Randomization to 12 Months | The endpoint will be a subject's change in Left Ventricular End Systolic Volume Index (a measure of the volume of blood in the left ventricle at the end of systole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 12 month - randomization visit difference in LVESVI. Negative values correspond to reductions in LVESVI over time. | Randomization to 12 Months | 
| Change in Left Ventricular End Systolic Volume Index (LVESVI) From Randomization to 18 Months | The endpoint will be a subject's change in Left Ventricular End Systolic Volume Index (a measure of the volume of blood in the left ventricle at the end of systole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 18 month - randomization visit difference in LVESVI. Negative values correspond to reductions in LVESVI over time. | Randomization to 18 Months | 
| Change in Left Ventricular End Systolic Volume Index (LVESVI) From Randomization to 24 Months | The endpoint will be a subject's change in Left Ventricular End Systolic Volume Index (a measure of the volume of blood in the left ventricle at the end of systole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 24 month - randomization visit difference in LVESVI. Negative values correspond to reductions in LVESVI over time. | Randomization to 24 Months | 
| Change in Left Ventricular End Diastolic Volume Index (LVEDVI) From Randomization to 6 Months | The endpoint will be a subject's change in Left Ventricular End Diastolic Volume Index (a measure of the volume of blood in the left ventricle at the end of diastole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 6 month - randomization visit difference in LVEDVI. Negative values correspond to reductions in LVEDVI over time. | Randomization to 6 Months | 
| Change in Left Ventricular End Diastolic Volume Index (LVEDVI) From Randomization to 12 Months | The endpoint will be a subject's change in Left Ventricular End Diastolic Volume Index (a measure of the volume of blood in the left ventricle at the end of diastole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 12 month - randomization visit difference in LVEDVI. Negative values correspond to reductions in LVEDVI over time. | Randomization to 12 Months | 
| Change in Left Ventricular End Diastolic Volume Index (LVEDVI) From Randomization to 18 Months | The endpoint will be a subject's change in Left Ventricular End Diastolic Volume Index (a measure of the volume of blood in the left ventricle at the end of diastole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 18 month - randomization visit difference in LVEDVI. Negative values correspond to reductions in LVEDVI over time. | Randomization to 18 Months | 
| Change in Left Ventricular End Diastolic Volume Index (LVEDVI) From Randomization to 24 Months | The endpoint will be a subject's change in Left Ventricular End Diastolic Volume Index (a measure of the volume of blood in the left ventricle at the end of diastole, normalized over body surface area). In other words, a measure of the size of the left ventricle. For each subject the measure is the 24 month - randomization visit difference in LVEDVI. Negative values correspond to reductions in LVEDVI over time. | Randomization to 24 Months | 
| Change in Left Ventricular Mass (LV Mass) From Randomization to 6 Months | The endpoint will be a subject's change in Left Ventricular Mass ( a measure of the size of the left ventricle) from randomization to 6 months. For each subject the measurement was calculated as 6 month - randomization visit difference in LV mass measurement. Negative values correspond to a reduction in LV mass over time. | Randomization to 6 Months | 
| Change in Left Ventricular Mass (LV Mass) From Randomization to 12 Months | The endpoint will be a subject's change in Left Ventricular Mass ( a measure of the size of the left ventricle) from randomization to 12 months. For each subject the measurement was calculated as 12 month - randomization visit difference in LV mass measurement. Negative values correspond to a reduction in LV mass over time. | Randomization to 12 Months | 
| Change in Left Ventricular Mass (LV Mass) From Randomization to 18 Months | The endpoint will be a subject's change in Left Ventricular Mass ( a measure of the size of the left ventricle) from randomization to 18 months. For each subject the measurement was calculated as 18 month - randomization visit difference in LV mass measurement. Negative values correspond to a reduction in LV mass over time. | Randomization to 18 Months | 
| Change in Left Ventricular Mass (LV Mass) From Randomization to 24 Months | The endpoint will be a subject's change in Left Ventricular Mass ( a measure of the size of the left ventricle) from randomization to 24 months. For each subject the measurement was calculated as 24 month - randomization visit difference in LV mass measurement. Negative values correspond to a reduction in LV mass over time. | Randomization to 24 Months | 
| Change in Left Ventricular End Diastolic Dimension (LVEDD) From Randomization to 6 Months | The endpoint will be a subject's change in LVEDD (a measure of the dimension of the left ventricle at the end of diastole). For each subject the measure was the 6 month - randomization visit difference in LVEDD value. Negative values correspond to reductions in LVEDD. | Randomization to 6 Months | 
| Change in Left Ventricular End Diastolic Dimension (LVEDD) From Randomization to 12 Months | The endpoint will be a subject's change in LVEDD (a measure of the dimension of the left ventricle at the end of diastole). For each subject the measure was the 12 month - randomization visit difference in LVEDD value. Negative values correspond to reductions in LVEDD. | Randomization to 12 Months | 
| Change in Left Ventricular End Diastolic Dimension (LVEDD) From Randomization to 18 Months | The endpoint will be a subject's change in LVEDD (a measure of the dimension of the left ventricle at the end of diastole). For each subject the measure was the 18 month - randomization visit difference in LVEDD value. Negative values correspond to reductions in LVEDD. | Randomization to 18 Months | 
| Change in Left Ventricular End Diastolic Dimension (LVEDD) From Randomization to 24 Months | The endpoint will be a subject's change in LVEDD (a measure of the dimension of the left ventricle at the end of diastole). For each subject the measure was the 24 month - randomization visit difference in LVEDD value. Negative values correspond to reductions in LVEDD. | Randomization to 24 Months | 
| Change in Left Ventricular End Systolic Dimension (LVESD) From Randomization to 6 Months | The endpoint will be a subject's change in LVESD (a measure of the dimension of the left ventricle at the end of systole). For each subject the measure was the 6 month - randomization visit difference in LVESD value. Negative values correspond to reductions in LVESD. | Randomization to 6 Months | 
| Change in Left Ventricular End Systolic Dimension (LVESD) From Randomization to 12 Months | The endpoint will be a subject's change in LVESD (a measure of the dimension of the left ventricle at the end of systole). For each subject the measure was the 12 month - randomization visit difference in LVESD value. Negative values correspond to reductions in LVESD. | Randomization to 12 Months | 
| Change in Left Ventricular End Systolic Dimension (LVESD) From Randomization to 18 Months | The endpoint will be a subject's change in LVESD (a measure of the dimension of the left ventricle at the end of systole). For each subject the measure was the 18 month - randomization visit difference in LVESD value. Negative values correspond to reductions in LVESD. | Randomization to 18 Months | 
| Change in Left Ventricular End Systolic Dimension (LVESD) From Randomization to 24 Months | The endpoint will be a subject's change in LVESD (a measure of the dimension of the left ventricle at the end of systole). For each subject the measure was the 24 month - randomization visit difference in LVESD value. Negative values correspond to reductions in LVESD. | Randomization to 24 Months | 
| Change in Mitral Regurgitation From Randomization to 6 Months | The endpoint will be a subject's change in mitral regurgitation (a measure of how much blood flows backwards into the heart due to the mitral valve not closing properly). The measure for each subject will be the 6 month - randomization visit difference in mitral regurgitation. Negative values reflect reductions in mitral regurgitation over time. | Randomization to 6 Months | 
| Change in Mitral Regurgitation From Randomization to 12 Months | The endpoint will be a subject's change in mitral regurgitation (a measure of how much blood flows backwards into the heart due to the mitral valve not closing properly). The measure for each subject will be the 12 month - randomization visit difference in mitral regurgitation. Negative values reflect reductions in mitral regurgitation over time. | Randomization to 12 Months | 
| Change in Mitral Regurgitation From Randomization to 18 Months | The endpoint will be a subject's change in mitral regurgitation (a measure of how much blood flows backwards into the heart due to the mitral valve not closing properly). The measure for each subject will be the 18 month - randomization visit difference in mitral regurgitation. Negative values reflect reductions in mitral regurgitation over time. | Randomization to 18 Months | 
| Change in Mitral Regurgitation From Randomization to 24 Months | The endpoint will be a subject's change in mitral regurgitation (a measure of how much blood flows backwards into the heart due to the mitral valve not closing properly). The measure for each subject will be the 24 month - randomization visit difference in mitral regurgitation. Negative values reflect reductions in mitral regurgitation over time. | Randomization to 24 Months | 
| Change in Cardiac Index From Randomization to 6 Months | The endpoint will be a subject's change in cardiac index (a measure of how much blood the left ventricle ejects in one minute, normalized over body surface area) from randomization to 6 months. The measure for each subject will be the 6 month - randomization visit value. | Randomization to 6 Months | 
| Change in Cardiac Index From Randomization to 12 Months | The endpoint will be a subject's change in cardiac index (a measure of how much blood the left ventricle ejects in one minute, normalized over body surface area) from randomization to 12 months. The measure for each subject will be the 12 month - randomization visit value. | Randomization to 12 Months | 
| Change in Cardiac Index From Randomization to 18 Months | The endpoint will be a subject's change in cardiac index (a measure of how much blood the left ventricle ejects in one minute, normalized over body surface area) from randomization to 18 months. The measure for each subject will be the 18 month - randomization visit value. | Randomization to 18 Months | 
| Change in Cardiac Index From Randomization to 24 Months | The endpoint will be a subject's change in cardiac index (a measure of how much blood the left ventricle ejects in one minute, normalized over body surface area) from randomization to 24 months. The measure for each subject will be the 24 month - randomization visit value. | Randomization to 24 Months | 
| Change in Interventricular Mechanical Delay (IVMD) From Randomization to 6 Months | The endpoint will be a subject's change in interventricular mechanical delay (a measure of dyssynchrony between ventricles, measured in ms) from randomization to the 6 month visit. The measure will be the 6 month - randomization visit difference in IVMD. | Randomization to 6 Months | 
| Change in Interventricular Mechanical Delay (IVMD) From Randomization to 12 Months | The endpoint will be a subject's change in interventricular mechanical delay (a measure of dyssynchrony between ventricles, measured in ms) from randomization to the 12 month visit. The measure will be the 12 month - randomization visit difference in IVMD. | Randomization to 12 Months | 
| Change in Interventricular Mechanical Delay (IVMD) From Randomization to 18 Months | The endpoint will be a subject's change in interventricular mechanical delay (a measure of dyssynchrony between ventricles, measured in ms) from randomization to the 18 month visit. The measure will be the 18 month - randomization visit difference in IVMD. | Randomization to 18 Months | 
| Change in Interventricular Mechanical Delay (IVMD) From Randomization to 24 Months | The endpoint will be a subject's change in interventricular mechanical delay (a measure of dyssynchrony between ventricles, measured in ms) from randomization to the 24 month visit. The measure will be the 24 month - randomization visit difference in IVMD. | Randomization to 24 Months | 
| Change in E Wave/A Wave Ratio (E:A Ratio) From Randomization to 6 Months | The endpoint will be a subject's change in E:A ratio (a measure of diastolic function) from randomization to 6 months. The measure for each subject will be the 6 month - randomization visit difference in E:A ratio. Typical values for the E:A ratio at a single time point are 1.04 in men and 1.03 in women. | Randomization to 6 Months | 
| Change in E Wave/A Wave Ratio (E:A Ratio) From Randomization to 12 Months | The endpoint will be a subject's change in E:A ratio (a measure of diastolic function) from randomization to 12 months. The measure for each subject will be the 12 month - randomization visit difference in E:A ratio. Typical values for the E:A ratio at a single time point are 1.04 in men and 1.03 in women. | Randomization to 12 Months | 
| Change in E Wave/A Wave Ratio (E:A Ratio) From Randomization to 18 Months | The endpoint will be a subject's change in E:A ratio (a measure of diastolic function) from randomization to 18 months. The measure for each subject will be the 18 month - randomization visit difference in E:A ratio. Typical values for the E:A ratio at a single time point are 1.04 in men and 1.03 in women. | Randomization to 18 Months | 
| Change in E Wave/A Wave Ratio (E:A Ratio) From Randomization to 24 Months | The endpoint will be a subject's change in E:A ratio (a measure of diastolic function) from randomization to 24 months. The measure for each subject will be the 24 month - randomization visit difference in E:A ratio. Typical values for the E:A ratio at a single time point are 1.04 in men and 1.03 in women. | Randomization to 24 Months | 
| Clinical Composite Score at 6 Months | The endpoint will be a subject's Clinical Composite Score at 6 months. The Clinical Composite Score is a 3 point score (Worsened, Unchanged, and Improved) based on a number of factors including: whether the subject has died, whether the subject has experienced a heart failure-related hospitalization, whether the subject has discontinued their therapy due to worsening heart failure, whether their New York Heart Association classification has improved or worsened since randomization, and whether they feel moderately or markedly better since randomization. | Randomization to 6 Months | 
| Clinical Composite Score at 12 Months | The endpoint will be a subject's Clinical Composite Score at 12 months. The Clinical Composite Score is a 3 point score (Worsened, Unchanged, and Improved) based on a number of factors including: whether the subject has died, whether the subject has experienced a heart failure-related hospitalization, whether the subject has discontinued their therapy due to worsening heart failure, whether their New York Heart Association classification has improved or worsened since randomization, and whether they feel moderately or markedly better since randomization. | Randomization to 12 Months | 
| Clinical Composite Score at 18 Months | The endpoint will be a subject's Clinical Composite Score at 18 months. The Clinical Composite Score is a 3 point score (Worsened, Unchanged, and Improved) based on a number of factors including: whether the subject has died, whether the subject has experienced a heart failure-related hospitalization, whether the subject has discontinued their therapy due to worsening heart failure, whether their New York Heart Association classification has improved or worsened since randomization, and whether they feel moderately or markedly better since randomization. | Randomization to 18 Months | 
| Clinical Composite Score at 24 Months | The endpoint will be a subject's Clinical Composite Score at 24 months. The Clinical Composite Score is a 3 point score (Worsened, Unchanged, and Improved) based on a number of factors including: whether the subject has died, whether the subject has experienced a heart failure-related hospitalization, whether the subject has discontinued their therapy due to worsening heart failure, whether their New York Heart Association classification has improved or worsened since randomization, and whether they feel moderately or markedly better since randomization. | Randomization to 24 Months | 
| CRT-P and CRT-D System Implant Success | The endpoint will be whether each subject who underwent an implant attempt of a Cardiac Resynchronization Therapy device, be it a pacing only device (CRT-P) or a pacing device with defibrillation capability (CRT-D), had a successful procedure (i.e. the generator, left ventricular lead, and right ventricular lead were successfully implanted). Only one implant attempt was allowed. | Initial Implant Procedure | 
| Incidence of Ventricular Tachyarrhythmias | Among subjects implanted with a Cardiac Resynchronization Therapy with Defibrillation device (CRT-D) and randomized, the endpoint was the time from randomization until the subject experienced a ventricular tachyarrhythmia. For each randomization arm, the number of CRT-D subjects who experienced at least one ventricular tachyarrhythmia post-randomization is reported, as well as the number of CRT-D subjects who did not experience one or more ventricular tachyarrhythmias post-randomization. | Participants were followed for the duration of the study, an average of 37.9 months post-randomization among CRT-D subjects. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Atrioventricular block, Cardiac Resynchronization Therapy, Pacemaker, Defibrillator, NYHA Class I, II or III Heart failure