Predictors of failed left bundle branch pacing implant in heart failure with reduced ejection fraction: Importance of left ventricular diameter and QRS morphology.

Left bundle branch pacing (LBBP) is considered an alternative to cardiac resynchronization therapy (CRT). However, LBBP is not suitable for all patients with heart failure. The aim of our study was to identify predictors of unsuccessful LBBP implantation in CRT candidates. A cohort of consecutive patients with indications for CRT were included. Clinical, echocardiographic, and electrocardiographic variables were prospectively recorded. A total of 187 patients were included in the analysis. LBBP implantation was successful in 152 of 187 patients (81.2%) and failed in 35 of 187 patients (18.7%). The causes of unsuccessful implantation were unsatisfactory paced QRS morphology (28 of 35 [80%]), inability to screw the helix (4 of 35 [11.4%]), lead instability (2 of 35 [5.7%]), and high pacing thresholds (1 of 35 [2.8%]). The left ventricular end-diastolic diameter (LVEDD), non-LBBB (left bundle branch block) QRS morphology, and QRS width were predictors of failed implantation according to the univariate analysis. According to the multivariate regression analysis, LVEDD (odds ratio 1.31 per 5-mm increase; 95% confidence interval 1.05-1.63 per 5-mm increase; P = .02) and non-LBBB (odds ratio 3.07; 95% confidence interval 1.08-8.72; P = .03) were found to be independent predictors of unsuccessful LBBP implantation. An LVEDD of 60 mm has 60% sensitivity and 71% specificity for predicting LBBP implant failure. When LBBP was used as CRT, LVEDD and non-LBBB QRS morphology predicted unsuccessful implantation. Non-LBBB triples the likelihood of failed implantation independent of LVEDD. Caution should be taken when considering these parameters to plan the best pacing strategy for patients.

Graterol FR ，Pujol-López M ，Borràs R ，Ayala B ，Uribe L ，Guasch E ，Regany-Closa M ，Niebla M ，Carro E ，Guichard JB ，Castel MÁ ，Arbelo E ，Porta-Sánchez A ，Sitges M ，Brugada J ，Roca-Luque I ，Doltra A ，Mont L ，Tolosana JM ... -  《-》

Outcomes with physiologic His bundle pacing in patients with narrow QRS complex.

In patients with narrow QRS complex, both ventricular and biventricular pacing is associated with increased cardiac morbidity and mortality. This risk is not decreased by ventricular pacing avoidance algorithms, which cause nonphysiologic atrioventricular (AV) delays. This study aimed to report outcomes in patients with narrow QRS complex when the paced complex is in normal range and physiologic AV delays are programmed. In 196 patients with QRS duration of 92 ± 10 ms, permanent pacing was done at the site of the His bundle electrogram. The pacemakers were then programmed to maintain physiologic AV delays and to increase heart rates in response to exercise. Patients received usual care and were observed for 3 years. The paced complex exhibited a delta wave, and the ventricular activation time, QRS axis, and lead I voltage remained in normal range. Physiologic programming resulted in His bundle pacing burden of 92%. In patients with decreased ejection fraction, there was significant improvement in left ventricular function, left ventricular dilation, and mitral regurgitation (P < .003). In patients with normal ejection fraction, left ventricular function remained normal without new valvular abnormalities. The 3-year all-cause mortality was 10%, and there was no increase in heart failure admissions. In patients with narrow QRS complex, when paced QRS morphology is maintained in normal range and AV dyssynchrony is avoided, His bundle pacing is associated with low all-cause mortality and improvement in abnormal echocardiographic parameters. The paced QRS morphology and physiologic AV delays may be important factors to evaluate in future trials of conduction system pacing.

Mahmud R ，Lee J ，Mohan A ，Lee M ，Phillips B ，Hakes S ，Talaei F ，Back Sternick E ... -  《-》

New-Onset Left Ventricular Dysfunction After Left Bundle Branch Pacing.

Left bundle branch pacing (LBBP) provides stable pacing parameters and has been suggested as an alternative for right ventricular pacing and cardiac resynchronization therapy. The aim of the study was to assess the incidence and etiology of new-onset left ventricular dysfunction (NOLVD) following LBBP in patients with baseline normal left ventricular (LV) function and cardiomyopathy patients with normalized LV function. Patients undergoing successful LBBP for symptomatic bradyarrhythmia or as an alternative to cardiac resynchronization therapy were included. Normalization of LV function was defined as improvement in LV ejection fraction to ≥50%. Patients with baseline normal LV function and those with recovered LV function after LBBP constituted the study group. Loss of conduction system capture (LOCSC) was defined as complete or partial loss of right bundle branch delay pattern along with inability to demonstrate capture transition during threshold assessment. A total of 426 patients were included; 59% (n = 250) had baseline normal LV function (group I) and 41% (n = 176) had recovered LV function after LBBP (group II). Mean follow-up duration of 28.3 ± 16.7 months. NOLVD was noted in 3.75% (n = 16; group I, n = 5, and group II, n = 11) of patients. The etiologies for NOLVD were LOCSC in 62.5% (n = 10), suboptimal atrioventricular (AV) delay in 18.7% (n = 3), atrial fibrillation in 6.3% (n = 1), and idiopathic in 12.5% (n = 2). LOCSC occurred at a mean interval of 9.2 ± 6.4 months after the initial implantation. Reinterventions (n = 6) including lead repositioning, AV delay optimization, and AV junction ablation resulted in renormalization of LV function in all 6 patients. Periodic assessment in device clinic is required because NOLVD from reversible causes can occur during follow-up in patients after LBBP.

Ponnusamy SS ，Ganesan V ，Nagalingam S ，Ramalingam V ，Mariappan S ，Moghal H ，Murugan S ，Kumar M ，Joseph R ，Vijayaraman P ... -  《-》

Transseptal Transition Patterns During Left Bundle Branch Area Lead Implantation.

Continuous deep septal pacing and signal recording during implantation of left bundle branch pacing (LBBP) lead enables to monitor beat-to-beat changes of electrocardiogram (ECG) and myocardial current of injury (COI) as the lead crosses the septum. This study aimed to characterize patterns of continuous QRS, ST-T, and COI change for monitoring of the lead depth and instantaneous determination of the obtained capture type (LBBP vs left ventricular septal pacing [LVSP]). The ECG and COI during lead implantation were scrutinized for sudden changes of V6 R-wave peak time, V1 initial and terminal R-wave amplitude, V3-V6 R-wave amplitude, repolarization pattern and S-wave amplitude in I, V5-V6, and COI drop. The sudden and gradual transition patterns were diagnosed depending on the presence or absence of the above beat-to-beat ECG phenomena, respectively. A total of 212 pacemaker recipients were analyzed; LBBP and LVSP were obtained in 77.4% and 22.6%, respectively. There were 4.7 ± 2.1 and 0.2 ± 0.6 beat-to-beat phenomena in LBBP and LVSP patients, respectively. The sudden transition pattern, recognized in 80.7%, had sensitivity and specificity for LBBP diagnosis of 98.8% and 81.2%, respectively. A sudden drop of COI (29.4 ± 8.5 mV to 12.8 ± 4.9 mV) was observed in 53.9% patients (LBBP was simultaneously obtained in 92.7%). Capture of left bundle branch during lead penetration is a beat-to-beat phenomenon. Two transseptal transition patterns were identified: 1) sudden, which is typical for obtaining LBBP; and 2) gradual, which is typical for obtaining LVSP. A sudden COI drop, a very observable phenomenon, also identified reaching the left subendocardial area.

Jastrzębski M ，Kiełbasa G ，Moskal P ，Bednarek A ，Rajzer M ，Burri H ，Curila K ，Vijayaraman P ... -  《-》

Comparison of left bundle branch area pacing between patients with pacing-induced cardiomyopathy and non-ischemic dilated cardiomyopathy.

Left bundle branch area pacing (LBBAP) seems to be an alternative to coronary sinus pacing in patients with non-ischaemic dilated cardiomyopathy (NI-DCM) with left bundle branch block (LBBB) and in pacing-induced cardiomyopathy (PICM). The aim of the study was to compare the response of LBBAP in severe forms of both entities. Prospective study of patients with severe forms of PICM and NI-DCM in NYHA II-IV who underwent LBBAP. Clinical, electrocardiographic, echocardiographic and electrical parameters were analysed and the medium-term prognostic impact was assessed. Eighty patients were included, 25 with PICM and 55 with NI-DCM. PICM patients were older (PICM 75 [IQR 71-83.5] y.o vs NI-DCM 72 [IQR 60-78.5] y.o;p=0.01) and with longer baseline QRS duration (PICM 180 [IQR 167-194] ms vs NI-DCM 168 [IQR 153-178] ms;p<0.01), with no differences in left ventricular ejection fraction (LVEF) or medical treatment. QRS reduction occurred in both groups, being greater in PICM (PICM CI 95% 54±20 ms, p<0.01; NI-DCM CI 95% 40±15 ms;p<0.01). A NT-ProBNP levels reduction and LVEF improvement were observed without differences between groups. At follow-up, there were no differences in admissions for HF (PICM 4.2% vs NI-DCM 11%;p=0.413), cardiac mortality (PICM 14.9% vs NI-DCM 2.9%;p=0.13) and all-cause mortality (PICM 21.7% vs NI-DCM 10.9%;p=0.08). LBBAP is an effective technique with a NT-ProBNP levels reduction and LVEF improvement in both groups without differences. At follow-up, both groups had a low rate of HF readmissions and there was a non-significant trend toward higher total mortality in PICM.

Perea-Armijo J ，Gutiérrez-Ballesteros G ，Mazuelos-Bellido F ，González-Manzanares R ，Huelva JM ，López-Aguilera J ，Pan M ，Segura Saint-Gerons JM ... -  《-》