Equilibrium radionuclide angiogram derived measures of dyssynchrony predict left ventricular remodeling after cardiac resynchronization therapy

Objectives 30% of the patients with advanced heart failure (HF) who receive cardiac resynchronization therapy (CRT) do not show clinical improvement. We have described 2 new equilibrium radionuclide angiogram (ERNA) derived parameters to assess LV dyssynchrony called synchrony (S) and entropy (E) that correlate with clinical outcomes after CRT. ERNA derived standard deviation of phase (SD of Ø) is a widely used marker of mechanical dyssynchrony. LV reverse remodeling has been shown to predict long-term survival after CRT. We prospectively evaluated S, E and SD Ø in patients requiring CRT to determine if these measures predict LV reverse remodeling after CRT.

Methods We studied 25 patients (19 males, mean age 64+/- 17 years) with HF, LVEF < 35% and QRS > 120 ms. ERNA and echocardiograms were performed before and after CRT and patients were followed for > 6 months. A 10% reduction in LV end-systolic volume index (LVESVI) was defined as clinically relevant reverse remodeling that was used to separate CRT responders from non-responders. Mean SD Ø, S, and E between responders and non-responders were determined and a student T test was used to determine p values between the two groups.

Results 65% of the pts were responders showing reverse remodeling after CRT. Baseline values of SD (Ø) and E could not differentiate responders from non-responders. Area under the ROC curve for S was 0.84, thus S can be used to identify CRT responders. A preoperative value of S ≤ .92 correctly identified response in 80% of patients, with 100% sensitivity and 56% specificity.

Conclusions S is a novel ERNA derived marker of LV dyssynchrony that predicts LV reverse remodeling after CRT.