His Pacing vs. Biventricular Pacing in Heart Failure Patients
- His-pacing was achieved in 72% of the patients randomized to the His-CRT group.
- Six-month follow-up LVEF increased by 16 in His-CRT vs. 13 in BiV-CRT (not significant), and improvements were seen in clinical and physical parameters in both treatment arms.
In patients with symptomatic heart failure and left bundle branch block (LBBB), how does His-bundle pacing correcting the bundle branch block (His-cardiac resynchronization therapy [CRT]) compare with traditional biventricular pacing (BiV-CRT)?
Patients with symptomatic heart failure, left ventricular ejection fraction (LVEF) ≤35%, and LBBB on electrocardiogram were randomized 1:1 to either His-CRT or BiV-CRT and followed for 6 months.
The study included 50 patients. At implantation, seven patients crossed over from His-pacing to LV-pacing in the His-CRT group and one patient crossed over from LV-pacing to His-pacing in the BiV-CRT group. His-corrective pacing was achieved in 72% of the patients in the His-CRT group. Intention-to-treat 6-month follow-up LVEF increased by 16 in His-CRT versus 13 in BiV-CRT (not significant), and improvements were seen in clinical and physical parameters in both treatment arms with no significant differences between the groups. Pacing thresholds were higher for His-CRT compared to BiV-CRT both at implantation (1.8V vs 1.2V, p < 0.01) and at 6-month follow-up (2.3V vs 1.4V, p < 0.01). The per-protocol LVEF was significantly higher at 6 months (48% vs. 42%, p < 0.05) and the end-systolic volume was lower (65 ml vs. 83 ml, p < 0.05) in His-CRT treated patients compared to BiV-CRT.
In heart failure patients with LBBB, His-CRT provided comparable clinical and physical improvement compared to BiV-CRT at the expense of higher pacing thresholds.
In the last decade, much progress has been made in conduction system pacing. Studies have shown that it is possible to correct the LBBB by pacing the distal portions of the bundle of His (His-CRT). The present study is a second small, randomized study comparing acute and near-term outcomes in patients with His-CRT and BiV-CRT. His-CRT was achievable in 72% of patients. Better tools should be developed to increase the ease and reliability of this procedure. Another new approach described by Huang et al. is perhaps even a more exciting and more reliable emerging technique to directly pace the left bundle branch.
Keywords: Arrhythmias, Cardiac, Bundle of His, Bundle-Branch Block, Cardiac Resynchronization Therapy, Electrocardiography, Heart Conduction System, Heart Failure, Myocardial Ischemia, Pacemaker, Artificial, Stroke Volume, Ventricular Function, Left
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