Acute and mid-term outcomes following single-lead left bundle branch area defibrillator implantation

Background

Left bundle branch area pacing with a single defibrillator lead (LBBAD) has emerged as a promising therapeutic option for patients requiring both implantable cardioverter-defibrillator (ICD) therapy and cardiac resynchronization therapy (CRT) 1,2. Evidence on its acute and mid-term performance remains limited.

Methods

Patients with a primary or secondary preventive ICD indication and an additional CRT indication were included in a retrospective single-center registry. A DF-4 ICD lead was implanted for left bundle branch area pacing, and defibrillation testing was performed in all procedures. Procedural success and safety were assessed. Follow-up was conducted at 30 days (short-term) and ≥60 days (mid-term). Device- and ECG-related, echocardiographic, and clinical parameters were compared with baseline.

Results

Nineteen patients were included (patient and procedure characteristics: Figure 1). Sixteen patients (84%) presented with heart failure and a left ventricular ejection fraction (LVEF) ≤35%. LBBAD implantation was successful in 16/19 patients (84%) (median of 2 [interquartile range 1; 2] screw-in attempts). Effective defibrillation was confirmed in all tested patients. Four patients (21%) required left bundle branch pacing-optimized-CRT due to persistent QRS prolongation due to left ventricular septal pacing. Acute pacing parameters were within normal limits (median pacing threshold 0.75 mV, sensing 10.9 mV, pacing impedance 530 Ω, shock impedance 79 Ω). QRS duration decreased from 172 [150; 192] ms to 127 [119; 133] ms (p<0.001). Median left ventricular activation time and V6–V1 inter-peak interval were 82 [76; 85] ms and 49 [42; 57] ms. Implantation failed in three patients due to no possible left bundle branch capture or sensing loss. No periprocedural complications occurred.

Short-term follow-up was available in 14 patients and mid-term follow-up in 10 patients (median 240 [104; 358] days). Device- and ECG-related parameters remained stable (Figure 2A, B). Median LVEF increased from 33 [27; 35] % to 44 [35; 49] % (p=0.001), with 7/9 (78%) primary-prevention patients improving from ≤35% to >35% (Figure 2C). Median left ventricular end-diastolic volume (161 ml to 129 ml, p=0.020) and global longitudinal strain (–8.4 % to –11.7 %, p=0.034) improved significantly. One patient experienced an appropriate ICD shock for ventricular fibrillation 14 days post-implantation and one patient an inappropriate shock due to permanent AF with rapid ventricular response.

Conclusion

Single-lead LBBAD implantation is safe and feasible, providing durable pacing and defibrillation performance with sustained QRS narrowing and improved LV function. Frequent LVEF recovery in primary-prevention patients highlights the need of further refinement of ICD indication criteria in this population.Table.Figure.