LAUSR

Type of funding sources: None. Favourable response criteria for cardiac resynchronization therapy (CRT) implantation are still under debate. We investigated the relationship between frontal QRS-Tangle and improvement of functional New York Heart Association (NYHA) class and thus favourable response to CRT.  Eighty-one patients were included in the study who CRT implanted. ECG and echocardiography were obtained 1 week before and after six month-1 years the CRT procedure. Patients were classified as "NYHA improvement" and "NYHA non-improvement" according to their NYHA class. The frontal QRS-T angle was calculated the absolute value of the difference between the QRS and T wave axes [Frontal QRS-Tangle=(QRS axis-T axis)] The mean age of patients was 64.5 ± 9.1 years. There was no difference between two groups in terms of demographic features. The post-implantation LVEF was higher in patients NYHA improvement group (p < 0.001). Post–implantation QRS duration (p = 0.008), cQT interval (p = 0.012), frontal QRS-T angle (p = 0.003) values were very shorter in NYHA improvement group (Table 1). In multivariate regression analysis showed the frontal QRS-T angle and age independent risk factors for improvement of NYHA class (p < 0.05). The receiver operating characteristics curve analysis (ROC) were showed the optimal cut-off value of predicting NYHA improvement for frontal QRS-Tangle was < 135 (AUC:0.69, 95%CI 0.575-0.814, p = 0.004). Conclusion: We found that after CRT implantation, functional NYHA class improvement was associated the shortened of QRS, cQT interval, increased LVEF and narrowed of the frontal QRS-Tangle  (<135 ms) was in both ischemic and non-ischemic patients Table 1 variables NYHA improvement group(43) NYHA non-improvement group (n = 34) p value age (years) 61.1 ± 9.9 66.5 ± 8.9 0.017 Post-implantation EF (%) 39 (30-50) 30 (20-37) <0.001 Pre-CRT Frontal QRS-T angle (º) 153.0 ± 57.8 155.7 ± 56.7 0.840 Post-CRT Frontal QRS-T angle (º) 118.4 ± 69.7 168.1 ± 67.8 0.003 Table 1