The association of volumetric response and long-term survival after cardiac resynchronization therapy

Clinical experience indicates that limited or no reverse left ventricular (LV) remodelling may not necessarily imply non-response to cardiac resynchronization therapy (CRT). We investigated the association of the extent of LV remodelling, mechanical dyssynchrony, and survival in patients undergoing CRT.

In 356 CRT candidates, three blinded readers visually assessed the presence of mechanical dyssynchrony (either apical rocking and/or septal flash) before device implantation and also its correction by CRT 12 ± 3 months post-implantation. To assess LV reverse remodelling, end-systolic volumes (ESV) were measured at the same time points. Patients were divided into four subgroups: no LV remodelling (ESV change 0 ± 5%), mild LV reverse remodelling (ESV reduction 5–15%), significant LV reverse remodelling (ESV reduction ≥15%), and LV volume expansion (ESV increase ≥5%). Patients were followed for all-cause mortality during the median follow-up of 36 months. Patients with LV remodelling as in the above defined groups showed 58, 54, and 84% reduction in all-cause mortality compared to patients with volume expansion. In multivariable analysis, LVESV change remained independently associated with survival, with an 8% reduction in mortality for every 10% decrease in LVESV (P = 0.0039), but an optimal cut-off point could not be established. In comparison, patients with corrected mechanical dyssynchrony showed 71% reduction in all-cause mortality (P < 0.001).

Volumetric response assessed at 1-year after CRT is strongly associated with long-term mortality. However, an optimal cut-off cannot be established. The association of the correction of mechanical dyssynchrony with survival was stronger than that of any volumetric cut-off.