A metric for evaluating the cardiac response to resynchronization therapy

Yidi Ge, Anne Christine Huth Ruwald, Valentina Kutyifa, Scott McNitt, Slava Polonsky, Helmut Klein, Ilan Goldenberg, Scott D. Solomon, Elyse Foster, Wojciech Zareba, Arthur J. Moss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Pages (from-to)1371-1377
Number of pages7
JournalAmerican Journal of Cardiology
Volume113
Issue number8
DOIs
StatePublished - 15 Apr 2014
Externally publishedYes

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