Role of left bundle branch pacing in preserving mechanical synchrony and myocardial work in patients with atrial ventricular block

Left bundle branch pacing was a novel advanced pacing method with a narrower-paced QRS duration. However, its role in preserving mechanical synchrony and myocardial work in patients with atrial ventricular block was not sufficiently evaluated.

To evaluate mechanical desynchrony and myocardial work characteristics after one year of pacing by left bundle branch pacing versus right ventricular pacing in patients with atrial ventricular block.

A prospective, observation study in 80 patients with second-degree type 2 and third-degree atrial ventricular block (40 patients with LBBP and 40 with right septal ventricular pacing RVP). All patients performed echocardiography before implantation and after one year.

The characteristics before implantation (age, gender, ejection fraction, QRS duration) and percentage of pacing were not significantly different between the two groups, but after implantation, paced QRS duration in LBBP pacing was significantly narrower than that in the RVP group (LBBP: 112±18ms, RVP: 139ms ±12ms, p<0.05). After 12 months, in electromechanical synchrony, LBBP induced significantly shorter peak strain dispersion (45.6 ±17.1ms vs. 54.26±12.7ms, P<0.05) and interventricular mechanical delay ([8.0ms (4.3–16.8) vs. 15.0ms(2.5–26.0), P<0.05) than RVP group. Compared with RVP group, LBBP induced greater global longitudinal strain (13.8±2.6% vs. 17.1±2.4%, P<0.05), global myocardial work index (1416.3±268.9mmHg% vs. 1974.3±624.1mmHg%, P<0.05) and global constructive work (1925.5±521.0 mmHg% vs. 2232.5 ±461.5 mmHg%, P<0.05).

After 12 months post-pacing, LBBP demonstrated better electromechanical synchrony, global longitudinal strain, and myocardial work than RVP.