Background: In patients who have an indication for permanent pacing and have an expectation of a high rate of ventricular stimulation, more physiologic ventricular activation by the use of His bundle pacing (HBP) may have a beneficial effect on the left ventricle (LV) function.
Objective: The study aims to evaluate the effect of HBP on LV function in patients with atrial fibrillation (AF) and bradycardia, depending on LV function at baseline.
Methods: A total of 135 consecutive patients with AF and bradycardia and with successfully achieved HBP were included in the study. The clinical and echocardiographic evaluation was performed at a baseline and after five to 15 months of follow-up at the outpatient clinic.
Results: A total of 73 patients, 19 of them females, aged 72.8±8.5, completed the follow-up period of an average of 7.7±2.5 months. Thirty-five of them had low LV ejection fraction (EF) below 51%, and 38 had normal LV EF over 50%, meaning EF of 60.4±6.0 and 39.1±8.4, respectively; p<0.0001. During follow-up in low-EF patients, EF increased, and end-systolic volume index (ESVi) decreased, but there was no change in EF and ESVi in patients with normal-EF at baseline, see Table. In the univariate regression analysis, the degree of the improvement of ESVi and EF in low-EF patients depended on the reduction of QRS duration and higher stimulation rate: r=0.53, p=0.003, and r=0.53, p=0.004, respectively and r=0.33, p=0.067, and r=0.51, p=0.004, respectively.
Conclusion: HBP in patients with AF and bradycardia in mid-term follow-up did not only deteriorate LV function but improved LV performance causing a reverse remodeling of LV in low-EF patients.
| Normal-EF patients | Low-EF patients |
| At baseline | At the end of follow-up | At baseline | At the end of follow-up |
| EF (%) | 60.4±6.0 | 57.9±5.8, NS | 39.1±8.4 | 44.9±11.6; p=0.0164 |
| ESVi (ml) | 25.0±8.7 | 25.1±6.7, NS | 53.1±20.4 | 45.2±21.7, p=0.0112 |
| QRS duration (ms) | 98.2±13.3 | 114.4±25.7, p=0.0083 | 143.4±41.9 | 119.4±21.9, p=0.0085 |
| Non-selective HBP - % of cases | 42 | 55 |
| EF - left ventricle ejection fraction, ESVi - left ventricle end-systolic volume index |
