Purpose: To characterize patients (pts) who underwent CRT implantation and to evaluate clinical and echocardiographic characteristics of super-responders.
Methods: Restrospective study of a single center analysing patients submitted to CRT implantation in the last 6 years (2012-2018). Super-responders were classified as patients who normalized left ventricular ejection fraction (LVEF >= 50%) at 6 months after implantation.
Results: We analysed 103 pts, 65% males with mean age of 70± 10 years, with optimized medical treatment. Non ischemic etiology was present in 74,5% of pts. 68,1% pts had QRS > 150ms and 80,9% had left bundle brunch block (LBBB). Mean LVEF was 27,9±7,5%, mean left ventricular end-diastolic volume índex (LVEDVI) was 113± 38 ml/m2. By the time of CRT implantation, 67% of pts were in SR (n=69) and 33% had AF (13,6% with paroxystic AF and 19,4% with persistent AF), and NYHA class 3 was present in 56,3% of pts. Subsequent hospitalizations occurred in 18,4%, and 11 pts died. 76,7% of pts were considered responders. 21,4% of pts were considered super-responders (n=22).
Comparing both groups (super-responders vs global population), we found no differences between groups in respect to gender (p=0,990), presence of previous sinus rythm (SR) (p=0.156), etiology (p= 0,053) and previous QRS width (p=0,086).
There were also no differences in long term outcomes (hospitalizations (p=0,371) or death (p=1)). However, super-responders had higher baseline ejection fraction (32 vs 26%, p= 0,002), lower left ventricular end-diastolic volume (167 vs 225 ml /m2, p=0,016) and lower left ventricular end-systolic volume (112 vs 156 ml/m2, p=0,016).
Conclusion: In this population, the super-responders appear to be pts with less advanced heart disease at baseline, with higher LVEF and lower left ventricular volumes. Surprisingly, we found no predictors of super-response in this population, not confirming previous studies that associated female sex, non-ischemic etiology and wider QRS duration with a super-response. This raises the question whether there are others non-recognized predictors of CRT response that would improve selection of patients for this therapy. Further studies are necessary to clarify this.