Conduction system pacing improved cardiac functions and functional capacity in heart failure with reduced ejection fraction and right bundle branch block

Conduction system pacing (CSP) is increasingly accepted as an alternative to biventricular pacing in heart failure (HF) patients with left bundle branch block (LBBB) and non-LBBB. However, its efficiency in right bundle branch block (RBBB) is ill-defined. Herein, we report on the clinical outcomes of CSP in HFrEF patients with wide QRS complex and RBBB morphology.

His-bundle (HBP) or LBB-area pacing (LBBAP) was attempted as a primary strategy in patients with RBBB, QRS duration ≥130 ms and left ventricular ejection fraction (LV EF) <35% and NYHA class II to IV HF despite optimized medical treatment for at least 6 months. Data on functional status, NT-pro-BNP levels and echocardiographic parameters were collected during follow-up and expressed as mean ± SEM, Statistical significance was calculated with Student’s paired t-test and chi square distribution.

CSP was performed in 12 RBBB-HF patients (age 64.3±2.9 years) with mean QRS duration of 150±4 msec and baseline LV EF of 25.4±2.3%. The aetiology of HF was ischaemic (6 patients) and non-ischaemic cardiomyopathy (6 patients). During the procedure, HBP was achieved in 7 and LBBAP in 5 patients, resulting in a significant reduction in the QRS-duration (115±2.6 msec, P<0.0001) as compared with baseline value. CSP improved LV function (LV EF= 31.8±2.8%, P=0.009) as well as NYHA functional class (25% of the patients with NYHA II and 75% with NYHA III before vs. 33% with NYHA I, 33% with NYHA II and 33% with NYHA III after CSP, P=0.048) as compared to what was obtained prior to the procedure. A numerical decrease was also found in NT-proBNP levels (4735±2606 ng/ml before CSP vs. 3972±1883 ng/ml after CSP) which did not reach the level of statistical significance (P=0.45).

In conclusion, CSP improved both quality of life and LV function in HFrEF patients with RBBB. Our results support the use of CSP in HFrEF patients with QRS width>130msec and RBBB morphology.