title: Predictive factors and clinical effect of optimized cardiac resynchronization therapy.
abstract: The aim of this study was to assess the effectiveness of cardiac resynchronization therapy (CRT) by intracardiac delay optimization using echocardiography. Sixty-five patients were implanted with a CRT device randomly assigned to receive simultaneous biventricular pacing or echo-optimized sequential CRT. Forty-two patients were defined as responders and 23 patients were classified as non-responders. During a 12-month follow-up period, the positive response rate, QRS duration, New York Heart Association class, mitral insufficiency grade, left ventricular end-systolic volume and LV end-diastolic volume were similar in the optimized and non-optimized groups (P>0.05), whereas 6-minute walking distance, quality-of-life score, left ventricular (LV) ejection fraction and aortic velocity time integral were significantly improved in the optimized group (P<0.05). The baseline QRS durations of the responders and non-responders were similar (P>0.05), whereas heart failure aetiology, clinical and echocardiographic measurements showed significant differences (P<0.05). The mean decrease in QRS duration after 12 months of CRT used for separating responders and non-responders was significantly different (P<0.05), and significant differences were observed in the mean decrease of QRS duration between responders and non-responders (P<0.05). Echocardiographic optimization may further improve the effectiveness of CRT. Moreover, severe mitral regurgitation and greater LV volume are likely to indicate a poor response to CRT.
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Xinjiang Medical University, Urumqi 830054,  P.R. China.
authors.forename: Guo-Jun
authors.initials: GJ
authors.lastname: Xu
authors.forename: Tian-Yi
authors.initials: TY
authors.lastname: Gan
authors.forename: Bao-Peng
authors.initials: BP
authors.lastname: Tang
authors.forename: Yi-Tong
authors.initials: YT
authors.lastname: Ma
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jin-Xin
authors.initials: JX
authors.lastname: Li
authors.forename: Yan-Yi
authors.initials: YY
authors.lastname: Zhang
authors.forename: Jiang
authors.initials: J
authors.lastname: Wang
authors.forename: Qi
authors.initials: Q
authors.lastname: Tang
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Wang
authors.forename: Yao-Dong
authors.initials: YD
authors.lastname: Li
authors.forename: Jiang-Hua
authors.initials: JH
authors.lastname: Zhang