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

Aims: 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. Methods and results: 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). Conclusion: 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.