P4378Comparison between left bundle branch pacing and His bundle pacing using two-dimensional speckle tracking echocardiography

Abstract

Abstract Background Although his bundle pacing (HBP) can achieve physiological electrical activation of the ventricles, its clinical use is limited by lower success rates, high and unstable pacing thresholds and loss of capture. Left bundle branch pacing (LBBP) has been proved to be able to correct Left bundle branch block (LBBB) and generate a narrower QRS duration than conventional RV pacing. However, its effects on ventricular synchronism and contraction function remains unknown. The current study is aimed to compare the echocardiographic characteristics between HBP and LBBP, and to explore whether LBBP leads to a comparable cardiac synchrony and deformation in comparison with HBP. Methods Forty-six pacing-indicated patients were prospectively enrolled. Twenty-nine patients underwent LBBP (17 male patients, mean age 69.6±13.7yrs, the LBBP group) and 17 patients underwent HBP (13 male patients, mean age 70.4±14.7yrs, the HBP group). LBBP was achieved by trans-septal method in the basal ventricular septum. Left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), left ventricular ejection fraction (LVEF), and tricuspid annulus plane systolic excursion (TAPSE) were obtained. Strains and time to peak strains of right ventricular free wall and 16 left ventricle segments were analyzed using two-dimensional speckle tracking echocardiography (2D STE). The standard deviation of time to peak strains of 16 left ventricular segments was calculated as PSD. Results Compared to the baseline, time to peak longitudinal strain (TTPS) of apical septum, apical lateral wall were shortened after 6 months of HBP, while they didn't change significantly after 6 months of LBBP. After pacemaker implantation, the LBBP group had a delayed TTPS of apical septum, apical lateral wall and basal RV free wall than the HBP group (LBBP vs. HBP: apical septum,358.44±61.98ms vs. 296.43±29.47ms; apical lateral wall, 373.11±55.80ms vs. 299.00±83.45ms; basal RV free wall, 404.31±72.93ms vs. 334.50±39.95ms, all p<0.05).However, PSD was comparable between the two groups (p>0.05). Compared to the baseline, global left ventricular longitudinal strain (LVGLS) and longitudinal strain of RV free wall (RVLS) were deteriorated after 6 months of HBP, while they were preserved in the LBBP group. After 6-month pacing, LVGLS and RVLS were significantly stronger in the LBBP group than those in the HBP group. (LVGLS, −16.10±3.75% vs. −13.18±4.11%; RVLS, −17.50±5.46% vs. −13.70±4.35%, both p<0.05). Conclusion Patients received LBBP had a comparable left ventricular synchronism and a better myocardial contraction compared to patients with HBP. LBBP may be a promising alternative pacing strategy. Two-dimensional STE is more sensitive than conventional echocardiography in assessing cardiac synchrony and segmental deformation.