The effect of left bundle branch block on pharmacotherapy and changes of left ventricular ejection fraction after the rapid-up titration of guideline-directed medical therapy in heart failure

Introduction The 2023 ESC Heart Failure (HF) Guidelines (GLs) recommend the rapid up-titration of GL-directed medical therapy (GDMT) for all patients (pts) after a HF hospitalisation to improve prognosis. The literature suggests that left bundle branch block (LBBB) may have a negative impact on the implementation of GDMT and prognosis in HF. Aims To assess the effect of the presence of LBBB on the achieved target doses (TDs) of GDMT and the changes in left ventricular ejection fraction (LVEF) after the 6-week rapid-up titration programme (RTP) of GDMT, in a real-world, consecutive cohort of HF pts. Patients and methods: In accordance with the 2023 ESC HF GLs, a 6-week RTP with weekly visits was implemented in the routine clinical practice of our HF Outpatient Clinic at our cardiology centre. In the current retrospective single-centre analysis, the data of the first 89 consecutive HF pts, completing the RTP after a HF hospitalisation were included (male: 79%, age: 58 [51-66] years, de novo HF: 67%, LVEF: 25 [20-32]%, NT-proBNP at discharge: 1491 [735-3077] pg/mL, GDMT at discharge: RASi/TD RASi: 100%/13%, βB/TD βB: 98%/3%, MRA/TD MRA: 99%/96%, SGLT2i: 96%, triple therapy [TT: RASi + βB + MRA]/TD TT: 97%/0%, quadruple therapy [QT: TT + SGLT2i]/TD QT: 93%/0%). Before RTP, no differences were observed in the LVEF between LBBB and non-LBBB pts (median LVEF: 23 [19-30] % vs 25 [20-33] %, p=0.147). The effect of LBBB (detected on the native ECG) on the achieved TDs of GDMT at 6-week RTP and the predictors of the achievement of TD QT at 6 weeks were analysed. Changes in LVEF at 3 months of follow-up (FUP) were also evaluated in the context of LBBB. Results After the 6-week RTP, a remarkable proportion of pts received TDs of GDMT (TD RASi: 78%, TD βB: 53%, TD MRA: 90%, TD TT: 45%, ≥ 50% of TDs of QT: 76%, TD QT: 42%). 14% of the total cohort had LBBB on the native ECG. At 6 weeks of RTP, an unfavourable tendency was observed in the TD application of βB (25% vs 57%, p=0.060; LBBB vs non-LBBB, respectively) and TT (17% vs 49%, p=0.058). According to the univariate binary logistic regression analysis, age, de novo diagnosis of HF, NT-proBNP at discharge, elevated serum potassium level (> 5 mmol/L) during the 6-week RTP and LBBB influenced the achievement of TD QT at the end of the RTP. At 3 months after the RTP, the non-LBBB subgroup had a significantly greater improvement of LVEF (median LVEF: 30 [20-34] % vs 45 [34-54] %, p<0.001). In the LBBB subgroup, 30% of pts achieved ≥10% improvement in LVEF, whereas 68% of non-LBBB pts experienced the same improvement (p=0.032). Conclusions According to our single-centre retrospective analysis, within a consecutive HF pt population who achieved TDs of QT at a remarkable rate after the RTP (TQ QT: 42%), LBBB was accompanied by less favourable improvement in LVEF at 3 months of FUP. Additionally, a higher proportion of non-LBBB pts experienced at least 10% improvement in LVEF.