Left Bundle Branch Pacing for Heart Failure and Left Bundle Branch Block Patients With Mildly Reduced and Preserved Left Ventricular Ejection Fraction

Background: Left bundle branch block (LBBB) may induce or aggra-vate heart failure (HF). Few data are available on patients with HF and LBBB with mildly reduced ejection fraction (HFmrEF; left ventricular ejection fraction [LVEF] 40%-50%) and those with preserved EF (HFpEF. LVEF >= 50%). We aimed to assess the long-term outcomes of left bundle branch pacing (LBBP) on cardiac function and remodelling in patients with LBBB and symptomatic HFmrEF and HFpEF.Methods: Nonischemic cardiomyopathy (NICM) patients with HFmrEF and HFpEF (LVEF from 40% to 60% as defined with the use of echo-cardiography) with LBBB who successfully underwent LBBP (n = 50) were prospectively included from 4 centres. Patient characteristics and echocardiographic and lead parameters were recorded at implantation and during follow-ups of 1, 3, 6, and 12 months.Results: All patients completed 1-year follow up. The LVEF was significantly improved from 46.5 +/- 5.2% at baseline to 60.0 +/- 6.1% (n = 50; P < 0.001) after 1-year follow up. Higher Delta LVEF and super -response rate were observed in the HFmrEF group (n = 30) than in the HFpEF group (n = 20).Conclusions: LBBP improved symptoms and reversed remodelling in patients with LBBB and symptomatic HF at 1-year follow-up. Improvement occurred even in HFpEF patients, and the resynchroni-sation effect was better in HFmrEF group.