Objectives: To compare electromechanical ventricular synchrony when pacing from different sites including right ventricular apex pacing (RVAP), right ventricular septum pacing (RVSP), His Bundle pacing (HBP), left bundle branch pacing (LBBP) and RVSP during unipolar pacing from the ring electrode of LBBP lead (RVSPring ) in each patient. Methods: Twenty patients with complete atrioventricular block (AVB) indicated for dual-chamber pacemaker implantation were included. Unipolar pacing at different sites including RVAP, RVSP，HBP，LBBP and RVSPring were successively performed. Pacing characteristics and echocardiogram parameters were compared among intrinsic rhythm and pacing at different sites. Results: Similar to HBP(114.84 ±18.67ms), narrower paced QRSd was found in LBBP(116.15±11.60ms) versus RVSPring(135.11±13.68ms), RVSP(141.75±14.08ms) and RVAP(158.15±21.41ms)(p＜0.001). LBBP showed comparable pacing parameters to RVAP or RVSP and were significantly better than HBP, with maintained cardiac function. TS-12-SD was significantly improved in LBBP(27.00±21.53ms) than RVAP(54.05±34.21ms, p=0.004) and RVSP(47.56±33.26ms, p=0.029) but similar to HBP(37.05±26.24ms, p=0.283) or RVSPring(42.16±26.19ms, p=0.107). Negative values of interventricular mechanical delay(IVMD) were only identified in LBBP(-20.16±18.47ms), significantly different from RVAP(33.68±30.98ms), RVSP (21.68±22.02ms), HBP (4.74±19.04ms) and RVSPring(14.56±26.76ms(all p＜0.001). Using Pearson’s analysis, Sti-LVAT was positively corelated with QRS, IVMD, TS-12-SD, LVEDV and LVESV while a negative relationship was identified for LVEF. Conclusions: Similar to HBP, LBBP achieved better electrical and mechanical left ventricular synchrony than conventional RV pacing. For interventricular synchrony, only LBBP initiated earlier LV activation than RV among these pacing strategies, in consistent with the RBBB pattern of paced QRS during LBBP.

Background: Prophylactic anticoagulation was recommended for stroke prevention in patients with hypertrophic cardiomyopathy(HCM) and atrial fibrillation(AF) regardless of CHA2DS2-VASC score but the strategy was in a dilemma for patients with contraindication to antigulants. Aims: To estimate the safety and efficacy of left atrial appendage occlusion(LAAO) in HCM patients with atrial fibrillation(AF). Methods and results: This prospective study included 25 HCM patients(age 70.04±11.62years, 72% male, 16/25(64.00%) had prior stroke) with AF eligible for LAAO. Clinical outcomes and echocardiographic parameters were collected and assessed during procedure and follow-up(3, 6, and 12months post-procedure). The composite safety outcomes included all-cause death, major bleeding and procedure-related complications. The primary efficacy outcome was defined as ischemic stroke and systemic embolization. Successful implantation was achieved in 24 patients(96%) using Watchman device without severe peri-device leaks (PDL), while one patient developed new-onset thrombus before access puncture on the operative day. Median follow-up was 1.5 years with a total of 38.1 patient-years. Only one patient experienced non-disabling ischemic stroke. The occurrence of major bleeding was 1/24(4.17%), with a remarkable reduction in annual 3 bleeding risk by 56.18% compared to the predicted rate. Device-related thrombus(DRT) was detected in 3/24(12.50%) patients. Neither serious procedure-related complications nor death events were reported in our study. Conclusion: Our study suggested the feasibility and safety of LAAO in HCM patients for stroke prevention. Whereas, thrombus formation remains a concern depending on hemodynamic abnormality associated with HCM. Further follow-up visits on larger sample size would facilitate the evaluation of LAAO in this high-risk cohort.