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

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Cardiac resynchronisation therapy (CRT) is known to acutely improve left ventricular (LV) function.
• Chronic CRT leads to further functional improvements and reverse remodelling of the LV.
• The relationship between acute functional changes and long-term outcomes after CRT requires further investigation.

Purpose of the Study:

• To investigate the association between acute improvements in LV systolic function, acute mechanical recoordination, and long-term reverse remodelling following CRT.
• To determine if acute functional improvements or acute mechanical recoordination are better predictors of long-term reverse remodelling after CRT.

Main Methods:

• Echocardiographic assessment of LV speckle tracking longitudinal strain, LV volumes, and ejection fraction (LVEF) in 35 patients before, acutely after, and 6 months after CRT.
• Invasive assessment of the maximal rate of LV pressure rise (dP/dtmax) in a subgroup of 25 patients during CRT implantation.
• Analysis of acute changes in dP/dtmax, LVEF, systolic discoordination (internal stretch fraction [ISF] and LV systolic rebound stretch [SRSlv]), and systolic dyssynchrony (standard deviation of peak strain times [2DS-SD18]) and their correlation with long-term reverse remodelling.

Main Results:

• CRT significantly improved LV mechanical recoordination (ISF and SRS) and function (dP/dtmax, stroke volume, LVEF) acutely and chronically.
• Acute mechanical recoordination, assessed by ISF and SRSlv, was strongly associated with long-term reverse remodelling (r=0.601 and r=0.765, respectively; p<0.001).
• Acute improvements in LV systolic function (dP/dtmax, LVEF) did not correlate with long-term reverse remodelling or the extent of acute recoordination.

Conclusions:

• Long-term reverse remodelling after CRT is primarily driven by acute mechanical recoordination rather than acute hemodynamic improvements.
• LV discoordination represents a crucial substrate for CRT that can be assessed and acutely restored.
• Targeting and improving mechanical discoordination may be a more effective strategy for optimizing CRT outcomes.