Left Ventricular Reverse Remodeling in Cardiac Resynchronization Therapy and Long-Term Outcomes.

OBJECTIVES

The aim of this study was to evaluate the association between improvement in left ventricular end-systolic volume (LVESV) with cardiac resynchronization therapy (CRT) and mortality and whether this relationship was modified by the presence of a left bundle branch block (LBBB) electrocardiographic pattern.

BACKGROUND

Left ventricular reverse remodeling in patients receiving CRT has been shown to predict outcomes. However, the extent to which reverse remodeling contributes to long-term survival is not well understood.

METHODS

Changes in LVESV were assessed in MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy) patients receiving CRT with a defibrillator (CRT-D) and echocardiograms available at 1 year (n = 752), stratified by LBBB, relative to long-term all-cause mortality, compared with those with implantable cardioverter-defibrillators (ICDs) only (n = 684).

RESULTS

In patients with LBBB, a reduction in LVESV of >35% (median) translated into significantly lower risk for long-term mortality (hazard ratio [HR]: 0.34; p < 0.001), heart failure (HF) events (HR: 0.21; p < 0.001), and HF or death (HR: 0.27; p < 0.001) compared with patients with ICDs only. Patients with reductions in LVESV ≤35% had a significantly lower risk for HF, and HF or death, and a nonsignificantly lower rate of death compared with those with ICDs only (HR: 0.74; p = 0.13). Risk reduction in HF events was uniform across all LVESV quartiles. In patients without LBBB, there was no survival benefit (HR: 0.68; p = 0.271) despite an LVESV reduction greater than the median (>27.6%). CRT-D patients without LBBB with the least reverse remodeling (quartile 1) had a more than 3-fold increased risk for death compared with those with ICDs only (HR: 3.11; p < 0.001).

CONCLUSIONS

In patients with LBBB, CRT-D-induced reduction in LVESV at 1 year is associated with long-term survival benefit. Despite left ventricular reverse remodeling with CRT-D, there is no survival benefit and potential harm in patients without LBBB.