Lecoq et al.
Definition of CRT response
Alive, no HF readmission, > 1 NYHA class improvement (or > 10% increase in peak VO2 and 6MW)
Follow-up (months)
6
Predictors of CRT response
QRS shortening during CRT
Achilli et al.
Definition of CRT response
Improved clinical composite score and LVEF increase ≥ 5%
Follow-up (months)
6
Predictors of CRT response
Smaller LVESD, longer interventricular mechanical delay
MIRACLE/MIRACLE ICD
Definition of CRT response
Alive and > 1 NYHA class improvement
Follow-up (months)
1, 3, and 6
Predictors of CRT response
None
Yeim et al.
Definition of CRT response
> 1 NYHA class improvement and no HF admission
Follow-up (months)
6
Predictors of CRT response
Nonischemic etiology, wider baseline QRS width, QRS shortening during
Mollema et al.
Definition of CRT response
≥ 1 NYHA class improvement or 10% decrease in LVESV
Follow-up (months)
6
Predictors of CRT response
None
PROSPECT
Definition of CRT response
Improved clinical composite score and LVESV decrease ≥ 15%
Follow-up (months)
6
Predictors of CRT response
None
Buck et al.
Definition of CRT response
LVESV decrease > 10%
Follow-up (months)
6
Predictors of CRT response
Interlead distance > 127 mm, septal-lateral delay > 60 ms, nonischemic etiology, LV end-diastolic diameter < 67 mm, use of ACE inhibitor, absence of tricuspid regurgitation
Rickard et al.
Definition of CRT response
LVESV decrease ≥ 10%
Follow-up (months)
> 2
Predictors of CRT response
Wider QRS
MADIT-CRT
Definition of CRT response
% decrease in LVEDV and response score
Follow-up (months)
12
Predictors of CRT response
Female, nonischemic etiology, LBBB, QRS > 150 ms, previous HF hospitalization, LVEDV > 125 mL/m2, left atrial volume < 40 mL/m2
PROSPECT-ECG
Definition of CRT response
Improved clinical composite score, LVESV decrease 15%
Follow-up (months)
6
Predictors of CRT response
LBBB morphology, LV paced QRS width and QRS shortening

ACE, angiotensin-converting enzyme; CRT, cardiac resynchronization therapy; HF, heart failure; LBBB, left bundle branch block; LV, left ventricular; LVEF, LV ejection fraction; LVEDV, LV end-diastolic volume; LVESD, LV end-systolic dimension; LVESV, LV end-systolic volume; MADIT-CRT, Multicenter Automatic Defibrillator Implantation Trial - Cardiac Resynchronization Therapy; MIRACLE, Multicenter InSync Randomized Clinical Evaluation; MIRACLE ICD, Mulitcenter Insync ICD Randomized Clinical Evaluation; 6MW, 6-minute walk; NYHA, New York Heart Association; PROSPECT, Predictors of Response to Cardiac Resynchronization Therapy; PROSPECT-ECG, Predictors of Response to Cardiac Resynchronization Therapy ECG. Modified from Ellenbogen et al.13 with permission from Elsevier