The QRS narrowing index for easy and early identification of responder to cardiac resynchronization therapy.

The rationale for cardiac resynchronization therapy (CRT) in patients with heart failure (HF) is based on the possibility of inducing substantial left ventricular reverse remodeling. It is well known that some of these patients don't benefit from this therapy (the so-called non-responders) [1,2]. No better predictors of a positive answer to CRT than pre-CRT QRS duration (QRSd) were found [3,4]. The aim of our study was to identify a parameter for an easy and early identification of responders to CRT. In this regard, according to Rickard et al., we identified and observed QRS index (QI), as an expression of electrical remodeling after CRT, and its relation with anatomic reverse remodeling, e…