Abstract 3245: Recoordination is Betten Than Resynchronization at Predicting Response to Cardiac Resynchronization Therapy
Background: A recent study has demonstrated that mechanical discoordination, as estimated from internal stretch fraction (ISF), is a better predictor of reverse remodeling after cardiac resynchronization therapy (CRT) than mechanical dyssynchrony. The time course and the extent of left ventricular recoordination after CRT and their relationship to response are unknown.
Methods: Radial strain and strain rate were determined in 6 mid-ventricular segments by speckle-tracking analysis in 20 patients at baseline, immediate after CRT implantation and 6-month follow-up. From radial strain and strain rate signals we derived an index of mechanical dyssynchrony (anteroseptal to posterior wall delay) and an index of mechanical discoordination, ISF, defined as the ratio of myocardial thinning to myocardial thickening during the systolic phase. CRT responders were defined as those patients where left ventricular (LV) end-systolic volume decreased by >15% at the 6-month follow-up.
Results: Immediately after CRT implantation, the CRT responders (N=12) demonstrated a significant reduction in ISF from 88±49% to 14±8% (P=0.002), which was reduced further at the 6-month follow-up (6±5%; P<<med>0.001 versus baseline; P=0.005 versus immediately after implantation). The non-responders, however, did not show a significant reduction in LV discoordination immediately after implantation (P=0.38). Linear regression analysis demonstrated a significant relationship between the immediate reduction in LV discoordination and the reduction in LV end-systolic volume at the 6-month follow-up. (y=0.32x+13; r=0.78; P=0.001). Conversely, there was no significant relationship between LV resynchronization and LV reverse remodeling (P=0.14). If the extent of acute LV recoordination was <20%, response to CRT at the 6-month follow-up was never observed. Conversely, all but one patients with LV resynchronization >20% responded to CRT.
Conclusions: LV recoordination after CRT is an acute phenomenon and predicts response to CRT at 6-month follow-up better than resynchronization.