Acute recoordination rather than functional hemodynamic improvement determines reverse remodelling by cardiac resynchronisation therapy

Purpose: Cardiac resynchronisation therapy (CRT) improves left ventricular (LV) function acutely, with further improvements and reverse remodelling during chronic CRT. The current study investigated the relation between acute improvement of LV systolic function, acute mechanical recoordination, and long-term reverse remodelling after CRT. Methods: In 35 patients, LV speckle tracking longitudinal strain, LV volumes & ejection fraction (LVEF) were assessed by echocardiography before, acutely within three days, and 6 months after CRT. A subgroup of 25 patients underwent invasive assessment of the maximal rate of LV pressure rise (dP/dt(max,)) during CRT-implantation. The acute change in dP/dt(max), LVEF, systolic discoordination (internal stretch fraction [ISF] and LV systolic rebound stretch [SRSlv]) and systolic dyssynchrony (standard deviation of peak strain times [2DS-SD18]) was studied, and their association with long-term reverse remodelling were determined. Results: CRT induced acute and ongoing recoordination (ISF from 45 +/- 18 to 27 +/- 11 and 23 +/- 12%, p < 0.001; SRS from 2.27 +/- 1.33 to 0.74 +/- 0.50 and 0.71 +/- 0.43%, p < 0.001) and improved LV function (dP/dt(max) 668 +/- 185 vs. 817 +/- 198 mmHg/s, p < 0.001; stroke volume 46 +/- 15 vs. 54 +/- 20 and 52 +/- 16 ml; LVEF 19 +/- 7 vs. 23 +/- 8 and 27 +/- 10%, p < 0.001). Acute recoordination related to reverse remodelling (r = 0.601 and r = 0.765 for ISF & SRSlv, respectively, p < 0.001). Acute functional improvements of LV systolic function however, neither related to reverse remodelling nor to the extent of acute recoordination. Conclusion: Long-term reverse remodelling after CRT is likely determined by (acute) recoordination rather than by acute hemodynamic improvements. Discoordination may therefore be a more important CRT-substrate that can be assessed and, acutely restored.