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Vol. 75. Issue 2.
Pages 182-184 (February 2022)
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Vol. 75. Issue 2.
Pages 182-184 (February 2022)
Scientific letter
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Initial experience with left bundle branch area pacing in patients with transthyretin cardiac amyloidosis
Experiencia inicial en estimulación en el área de la rama izquierda en pacientes con amiloidosis cardiaca por transtirretina
Francisco José Bermúdez-Jiméneza,b,c,
Corresponding author

Corresponding author:
, Manuel Molina-Lermaa,b, Rosa Macías-Ruiza,b, Pablo Sánchez-Millána,b, Juan Jiménez-Jáimeza,b, Miguel Álvareza,b
a Servicio de Cardiología, Hospital Universitario Virgen de las Nieves, Granada, Spain
b Instituto de Investigación Biosanitaria ibs.GRANADA, Granada, Spain
c Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
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Table 1. Baseline characteristics and outcomes at 3 months after the start of LBBP treatment
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To the Editor,

We are witnessing an increase in the understanding of cardiac amyloidosis due to abnormal deposits of the protein transthyretin (ATTR), both its hereditary form and acquired (or senile) form. Current data from Spain indicate that ATTR is the most common type of cardiac amyloidosis. Heart failure (HF) is the most frequent presentation and close to 35% of patients will have deterioration in left ventricular ejection fraction (LVEF) and short survival.1 Furthermore, a substantial number of patients with ATTR have conduction system abnormalities (7% have advanced atrioventricular block) or left ventricular systolic dysfunction.2 Previous studies have shown a deleterious effect from frequent ventricular pacing and a clinical benefit from cardiac resynchronization therapy (CRT) in selected patients with ATTR.3 Recently, physiological pacing of the left bundle branch (LBBP) has become a safe, feasible alternative for those who require antibradycardia treatment or CRT.4 Our objective was to study the technical viability of LBBP in ATTR and analyze its clinical effects in a pilot experience. The study was approved by the Granada province Research Ethics Committee. Patients gave written consent for study participation and publication.

We present 3 patients with ATTR, HF, and left ventricular systolic dysfunction requiring permanent ventricular pacing; because they remained symptomatic, LBBP was performed with the aim of optimizing CRT and preventing LVEF deterioration as a consequence of the permanent pacing (table 1).

Table 1.

Baseline characteristics and outcomes at 3 months after the start of LBBP treatment

  Patient 1    Patient 2    Patient 3   
Sex  Male    Male    Male   
Age, y  83    72    84   
Type of ATTR  Acquired    Hereditary (p.Val142Ile)    Acquired   
Carpal tunnel syndrome       
Pulmonary hypertension       
Glomerular filtration rate < 45 mL/min/1.73 m2       
AF  Permanent    Paroxysmal    Paroxysmal   
Indication  SND    cAVB    SND   
RAASI  No    Enalapril    Candesartan   
Beta-blockers  No    No    Bisoprolol   
MRA  Spironolactone    No    Spironolactone   
Tafamidis  No    Yes    No   
Diuretics  Furosemide 120 mg    Furosemide 120 mg    Furosemide 80 mg   
SGLT2i  No    No    No   
Rhythm  Permanent AF    Permanent AF    Paroxysmal AF   
Previous device  CRT-P (basal inferolateral coronary sinus)    No    CRT-P (mid inferolateral coronary sinus)   
  Baseline  3 mo  Baseline  3 mo  Baseline  3 mo 
LVEF, %  37  37  43  57  30  49 
QRS, ms  156  128  186  138  248  148 
BNP, pg/mL  1513  1411  1469  1150  959  564 
Emergency department visits due to cardiac cause (6 mo) 
Hospitalization for HF (1 y) 
[0,1-7]Electric parameters relating to left bundle branch pacing             
QRSd, ms  128    138    148   
LVAT, ms  88    92    96   
Left bundle capture threshold, V × 0.4 ms  0.75    0.75     
Mode  VVIR    DDD    DDDR   
Percentage ventricular pacing  97    99.6    99.9   

AF, atrial fibrillation; ATTR, transthyretin amyloidosis; BNP, brain natriuretic peptide; cAVB, complete atrioventricular block; CRT-P, cardiac resynchronization therapy; CVE, cerebrovascular event; HF, heart failure; LVAT, left ventricular activation time; LVEF, left ventricular ejection fraction; MRA, mineralocorticoid receptor antagonists; NYHA, New York Heart Association functional class; RAASI, renin-angiotensin-aldosterone system inhibitors; SGLT2i, sodium-glucose cotransporter type 2 inhibitor; SND, sinus node dysfunction.

The first patient was an 83-year-old man with acquired ATTR who had a syncopal episode caused by sinus node dysfunction (SND) and nodal escape, with slight wall hypertrophy and mildly reduced LVEF. The patient had a dual chamber pacemaker, and 2 years later, in light of the etiological diagnosis, development of atrioventricular disease, and LVEF deterioration requiring permanent pacing, he was changed to conventional CRT. His progress was unfavorable, and he developed atrial fibrillation, had a deterioration in functional class and was hospitalized for HF, triggering the decision to use LBBP.

The second patient was a 72-year-old man with hereditary ATTR (p.Val142Ile variant) and paroxysmal atrial fibrillation with a severe deterioration in HF functional class since the diagnosis of the disease (1 admission and 2 visits to the emergency department for HF). He subsequently developed atrioventricular block, and was treated with LBBP with the aim of avoiding LVEF deterioration.

The third patient was an 84-year-old man who was under follow-up for ventricular hypertrophy of unknown etiology since diagnosis 4 years prior. During the follow-up, he developed difficult-to-control persistent atrial fibrillation, left bundle branch block, and progressive left ventricular systolic dysfunction. After the onset of the syncopal sinus node dysfunction, a CRT device was implanted (QRSd, 160ms). Eventually, 1 year later, once considered a nonresponder and with deterioration in functional class, it was decided to use LBBP, and a QRSd of 140ms was obtained (figure 1).

Figure 1.

A: baseline electrocardiogram with first-degree AVB and right bundle branch block and left axis deviation. B: LBBP; typical rsr’ morphology with normal axis. C: typical “W” morphology in V1 before lead penetration of IVS. D: initial penetration of the IVS with shortening of the paced QRS interval (212ms) and of the LVAT interval (162ms). E: capture of the left bundle with rsr’ morphology in V1, narrower QRS interval (148ms) and shorter LVAT (108ms). AVB, atrioventricular block; IVS, interventricular septum; LBBP, left bundle branch pacing; LVAT, left ventricular activation time. gr1.


In the 3 patients, a guide catheter was used for septal pacing (C315 HIS, Medtronic Inc, USA). Over that, a lead was introduced (Select-Secure model 3830 69cm, Medtronic Inc., USA), connected to the polygraph to record intracavity signal. The guide catheter was positioned 2 cm apically to the His bundle electrogram and, using 6 to 8 clockwise turns, the lead penetrated the interventricular septum until capture of the left bundle branch was achieved. In the 3 patients, the following 4 criteria were used for LBBP (figure 1):5

  • Shortening of the spike-R wave interval in V6

  • rsr’/rsR’ morphology in V1

  • Narrowing of the QRS complex after septal penetration

  • Change in selective-nonselective capture

In our experience, the success rate of the implant was 100%, with no incidents of note. In all cases, a paced QRS that was narrower than before was achieved.

Although the 3 patients were of advanced age, had atrial fibrillation (paroxysmal in 2 and permanent in 1), chronic kidney disease (stage G3a), and advanced HF (New York Heart Association [NYHA] functional class III-IV/IV), at 3 months after starting LBBP, all had improved functional class, with a slight reduction in natriuretic peptide levels (table 1). Regarding LVEF, 2 patients had an increase, but the first did not. Lastly, although statistical inferences are not possible due to the small sample size, there was a reduction in the number of hospitalizations after 1 year and emergency department visits for HF at 6 months after LBBP (table 1).

In conclusion, this study is limited by its small sample size, its retrospective design, the variability in echocardiographic measurements, and the short follow-up. However, in our initial small cohort of patients with ATTR, LBBP proved to be a viable and effective therapeutic option in the short-term (3 months) for the optimization of CRT and which allowed improvement in HF symptoms. This hypothesis should be confirmed in larger, prospective studies.


This study did not receive any specific funding from public sector, commercial, or not-for-profit funding bodies.


F.J. Bermúdez-Jiménez collected and analyzed the data; he wrote the manuscript with the help of the other authors. M. Molina-Lerma and P. Sánchez-Millán performed and supervised the technical procedures. J. Jiménez-Jáimez and R. Macías-Ruiz conceived the idea presented. M. Álvarez supervised the overall process. All authors discussed the results and contributed to the final manuscript.


The authors have nothing to declare.

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Clinical profile and outcome of cardiac amyloidosis in a Spanish referral center.
Rev Esp Cardiol., 74 (2021), pp. 149-158
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Clinical characteristics of wild-type transthyretin cardiac amyloidosis: disproving myths.
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Copyright © 2021. Sociedad Española de Cardiología
Revista Española de Cardiología (English Edition)

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