QRS length/left ventricular mass index: a novel predictive factor of response to cardiac resynchronization therapy

Abstract

Abstract Introduction The length of QRS interval is an extensively studied predictor of response to CRT. There is little evidence of the probability of response in patients with QRS between 130 and 150 ms and its relationship with LV mass. (1,2) Objective Evaluation of the QRS length/LV mass index (QRS/LVMi) as a "relative dyssynchrony" marker and its correlation to response after CRT implantation. Methods Retrospective study that included patients over 18 years of age with HFrEF (LVEF ≤ 35%) and CRT implantation between years 2018 – 2022 (n = 92). QRS length (ms) was measured with CardioLab 3.0 Software and divided by LV mass (g), according to Deveraux equation using echocardiography measurements. Primary outcome was response to CRT defined by: Improvement of at least 1-point in NYHA functional class + (i) increase of at least 5% in LVEF or (ii) decrease of at least 15% in LVESD. Results QRS/LVMi value ≥ 0.6 was associated with a higher frequency of response to CRT than values < 0.6 (83% responders vs 17% non responders; OR 5.1; CI 2.7–12.1, p < 0.05). There was no difference in response to CRT between QRS > 150 ms and 130 – 150 ms in patients with QRS/LVMi ≥ 0.6 (80% vs 82% of responders, p = 0.8). A multivariate analysis showed a significantly higher probability of response to CRT in patients with QRS/LVMi ≥ 0.6 compared to other known predictive factors (OR 4.1; CI 1.2–12, p < 0.05). Conclusions The use of QRS/LVMi was associated with a better prediction of response to CRT than other traditional factors. There was no difference in response between QRS > 150 ms and 130 - 150 ms in patients with QRS/LVMi ≥ 0.6, suggesting the efficacy of CRT in patients with shorter QRS interval length and less LV mass, highlighting the importance of the concept of relative dyssynchrony.Total Response according QRS/LMViMultivariate analysis