Abstract 4345: Identification of Responders to CRT by Stress Echo: No Contractile Reserve, No Party
Cardiac resynchronization therapy (CRT) is increasingly used, but the identification of “responders” remains challenging.
Aim: to assess the value of rest (for dyssynchrony, DYS) and stress (for contractile reserve, CR) echo to identify responders. In a prospective, multicentre study design, we enrolled 55 patients (age 69±8 years; 60% with ischemic etiology) referred to CRT, all with LV ejection fraction ≤35%, NYHA ≥IIb and QRS duration ≥130 milliseconds. All patients underwent a baseline study for DYS (Tissue Doppler criteria, 6-segment approach, Bax dyssynchrony index > 65 ms) and dobutamine stress echo (up to 40 mcg/Kg/min, with presence of CR defined as a wall motion score index, WMSI, increase > 0.20) with core lab reading. “Responders” were identified by clinical (survivors, with NYHA class improvement ≥1 grade) and/or echocardiographic (LV end-systolic volume, ESV, decrease ≥15% at 6-months follow-up) criteria. In the follow-up, 28 (51%) patients were responders to CRT. At individual patient analysis, CR was more often associated with a favourable outcome whereas DYS criteria were equally present in the 2 groups: see figure⇓. At multivariate analysis, CR (OR=6.2, 95% CI=1.4–27.6) and ischemic etiology (OR=0.20, 95% CI=0.05–0.73) were the best predictors of clinical and echo response to CRT, regardless of DYS. Patients with CR during stress echo show a favourable clinical and reverse LV remodelling response to CRT. This finding shifts the focus from electrical (DYS) to the myocardial substrate of functional response to CRT: no muscle, no party!