title: A metric for evaluating the cardiac response to resynchronization therapy.
abstract: We hypothesized that the response to cardiac resynchronization therapy with a defibrillator (CRT-D) in patients with mildly symptomatic heart failure (HF) is more favorable than the commonly referenced figure of 70%. This study involves the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) study population in which paired echocardiograms from baseline and 1-year follow-up were available in 621 implantable cardioverter-defibrillator-treated patients and 749 patients treated with CRT-D. We prespecified CRT-D responders as the patients who at 1-year follow-up had a reduction in left ventricular end-systolic volume (LVESV) that corresponded to the top (best) quintile of LVESV reduction in the implantable cardioverter-defibrillator-treated patients, that is, a ≥17% reduction in LVESV. Using this metric, 88% of patients treated with CRT-D and 91% of the patients treated with CRT-D with left bundle branch block (LBBB) were identified as cardiac resynchronization therapy responders. Landmark multivariate Cox model analyses revealed a significant interaction (p=0.038) involving LVESV (responders vs nonresponders) and LBBB (present vs not present) in risk reduction for HF or death. The interaction finding indicates that cardiac resynchronization therapy responders with LBBB have a significantly lower risk for HF or death (hazard ratio [HR] 0.24) than patients without LBBB (HR 0.62). In the patients treated with CRT-D, LVESV response was associated with reduction in the risk of death (HR 0.20, p<0.001). An increasing percent reduction in LVESV was associated with progressively lower rates of HF or death, a finding consistent with a dose-response relation. In conclusion, approximately 90% of CRT-D-treated patients in MADIT-CRT had a significant and meaningful reduction in LVESV, and these LVESV responders had reduced rates of cardiac events during long-term follow-up.
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York.
authors.forename: Yidi
authors.initials: Y
authors.lastname: Ge
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York; Department of Cardiology, Gentofte University Hospital, Copenhagen, Denmark.
authors.forename: Anne-Christine Huth
authors.initials: AC
authors.lastname: Ruwald
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York.
authors.forename: Valentina
authors.initials: V
authors.lastname: Kutyifa
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York.
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York.
authors.forename: Slava
authors.initials: S
authors.lastname: Polonsky
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York.
authors.forename: Helmut
authors.initials: H
authors.lastname: Klein
authors.affiliation: Sheba Medical Center and Tel Aviv University, Tel Aviv, Israel.
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Solomon
authors.affiliation: University of California San Francisco Hospital, San Francisco, California.
authors.forename: Elyse
authors.initials: E
authors.lastname: Foster
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York. Electronic address: heartajm@heart.rochester.edu.
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
mesh_terms: D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D002306:Cardiac Volume / Q000502:physiology*; D009202:Cardiomyopathies / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D004452:Echocardiography; D004554:Electric Countershock / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013318:Stroke Volume / Q000502:physiology; D013599:Systole; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*