中文摘要：

研究目的：对于轻度心功能受损的高度房室传导阻滞患者，明确右室起搏的最优化位置，同时明确哪一类患者能够从最优化的右心窜起搏中获益。创新要点：首次明确相比于右心室心尖部起搏，中位间隔部起搏明显改善轻度心功能受损，尤其是左室射血分数在35％-40％的高度房室传导阻滞患者的临床预后。研究方法：随机分配进入中位间隔部起搏或心尖部起搏的患者，在基线状态下记录N-末端脑钠肽前体、六分钟步行试验以及心超结果；随访18个月后观察上述结果变化。同时，根据射血分数的不同进行亚组分析。重要结论：相比于右心室心尖部起搏，中位间隔部起搏能够改善轻度心功能受损的高度房窒传导阻滞患者的临床预后，尤其对于左窀射血分数在35%-40％的患者。

英文摘要：

Objective： We are aimed to investigate whether right ventricular mid-septal pacing （RVMSP） is superior to conventional right ventricular apical pacing （RVAP） in improving clinical functional capacity and left ventricular ejection fraction （LVEF） for patients with high-degree atrio-ventricular block and moderately depressed left ventricle （LV） function. Methods： Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF （ranging from 35% to 50%） were randomly allocated to RVMSP （n=45） and RVAP （n=47）. New York Heart Association （NYHA） functional class, echocardiographic LVEF, and distance during a 6-min walk test （6MWT） were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide （NT-proBNP） were measured using an enzyme-linked immunosorbent assay （ELISA） kit. Results： Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MVVT （485 m vs. 517 m） and LVEF （36.7% vs. 41.8%） were increased, but BNP levels were reduced （2352 pg/ml vs. 710 pg/ml） in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% （for all comparisons, P〈0.05）. However, clinical function capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. Conclusions： RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.