Ventricular pacing dependency after transcatheter aortic valve replacement: a prospective cohort

Background

Atrioventricular conduction disturbance occurs in a significant number of patients undergoing transcatheter aortic valve replacement (TAVR). However, not all cases are ventricular pacing-dependent. Thus, we aimed to study the incidence, predictors, and outcomes of new ventricular pacing dependency (VpDep) after TAVR.

Methods

We prospectively analyzed 130 consecutive transfemoral TAVR cases performed in Ramathibodi Hospital between 2015 and 2020. Three patients with prior ventricular pacing-dependent on cardiac implantable electronic devices (CIEDs) were excluded. The endpoints were VpDep at 1 month and all-cause mortality at the follow-up period end in 2021. The effects of variables on VpDep and all-cause mortality were evaluated using multivariate binary logistic regression and Cox regression analyses, respectively. First-degree atrioventricular block (AVB) was considered severe when the PR interval was >300 ms.

Results

Of the 127 patients [mean age, 81.8 years; 62.2% females; 67.7% balloon-expandable (BE) device], 7 patients (5.5%) had CIEDs implanted before TAVR that were not ventricular pacing-dependent. TAVR was successfully performed in 126 (99.2%) patients. Periprocedural stroke, cardiac tamponade, and major bleeding occurred in 2 (1.6%), 4 (3.1%), and 4 (3.1%) patients, respectively. The VpDep incidence at 1 month was 7.9% (n=10) among all patients and 34.5% among those with CIEDs (n=29). VpDep was more likely to occur in patients with pre-existing right bundle branch block (RBBB) [odds ratio (OR), 21.38; 95% confidence interval (CI): 3.28-139.33; P=0.001] and severe 1st degree or Mobitz I AVB (OR, 14.79; 95% CI: 1.65-132.74; P=0.016). After a mean follow-up of 25.8 months [standard deviation (SD), 21.2 months], death from any cause occurred in 18 patients (14.2%). However, VpDep was not associated with an increased mortality.

Conclusions

In this real-world cohort, pre-existing conduction abnormalities were significantly associated with a higher risk of VpDep. Mortality was similar between patients with and without VpDep.

Feasibility and Outcomes of Upgrading to Left Bundle Branch Pacing in Patients With Pacing-Induced Cardiomyopathy and Infranodal Atrioventricular Block

His bundle pacing (HBP) can reverse left ventricular (LV) remodeling in patients with right ventricular (RV) pacing-induced cardimyopathy (PICM) but may be unable to correct infranodal atrioventricular block (AVB). Left bundle branch pacing (LBBP) results in rapid LV activation and may be able to reliably pace beyond the site of AVB. Our study was conducted to assess the feasibility, safety, and outcomes of permanent LBBP in infranodal AVB and PICM patients. Patients with infranodal AVB and PICM who underwent LBBP for cardiac resynchronization therapy (CRT) were included. Clinical evaluation and echocardiographic and electrocardiographic assessments were recorded at baseline and follow-up. Permanent LBBP upgrade was successful in 19 of 20 patients with a median follow-up duration of 12 months. QRS duration (QRSd) increased from 139.3 ± 28.0 ms at baseline to 176.2 ± 21.4 ms (P < 0.001) with right ventricular pacing (RVP) and was shortened to 120.9 ± 15.2 ms after LBBP (P < 0.001). The mean LBBP threshold was 0.7 ± 0.3 V at 0.4 ms at implant and remained stable during follow-up. The left ventricular ejection fraction (LVEF) increased from 36.3% ± 6.5% to 51.9% ± 13.0% (P < 0.001) with left ventricular end-systolic volume (LVESV) reduced from 180.1 ± 43.5 to 136.8 ± 36.7 ml (P < 0.001) during last follow-up. LBBP paced beyond the site of block, which results in a low pacing threshold with a high success rate in infranodal AVB patients. LBBP improved LV function with stable parameters over the 12 months, making it a reasonable alternative to cardiac resynchronization pacing via a coronary sinus lead in infranodal AVB and PICM patients.

Surgical septal myectomy outcome for obstructive hypertrophic cardiomyopathy after alcohol septal ablation

Background

Although surgical treatment of residual obstruction after alcohol septal ablation (ASA) is often challenging in patients with obstructive hypertrophic cardiomyopathy (OHCM) there are very few relevant clinical reports. Thus, outcomes of surgical septal myectomy (SSM) in this subgroup of patients remain to be determined. Therefore, this study aimed to determine the surgical and follow-up outcomes in patients with OHCM exhibiting residual obstruction after ASA.

Methods

We collected case data for 62 patients with OHCM and residual obstruction after ASA who underwent SSM at Fuwai Hospital between January 2002 and June 2019. Propensity score matching with patients having had a myectomy as the only invasive procedure—was conducted in a 1:2 ratio. Echocardiography parameters, surgery results, and follow-up outcomes were compared between the groups.

Results

The prior ASA group had a higher incidence of complete atrioventricular block (AVB) and subsequently postoperative permanent pacemaker (PPM) implantation than the primary myectomy group (9.7% vs. 1.6%, P=0.01). Two patients died within 30 days after surgery in the prior ASA group, and one patient died in the primary myectomy group, with an operative mortality rate of 3.2% and 0.8%, respectively (P=0.2). The 5-year event-free survival rate was 86.0% in the prior ASA group (median follow-up period: 3.2 years; mean: 3.9±2.6 years; maximum, 10.6 years) and 88.5% in the primary myectomy group (median follow-up period: 2.4 years; mean 2.8±1.7 years; maximum, 9.1 years) (P=0.2). During follow-up, four of 62 (6.5%) patients in the prior ASA group and one of 124 (0.8%) patients in the primary myectomy group progressed to advanced heart failure (P=0.025).

Conclusions

Patients with OHCM following ASA are at an increased risk of developing AVB after SSM. Their surgical outcomes, and long-term survival rate were satisfactory and, osimilar to those for patients having had a myectomy as the only invasive procedure. In addition, they had an increased risk of advanced heart failure after SSM in the present study.

Electrical disorders in atrial septal defect: genetics and heritability

Atrial septal defect (ASD) is one of the most common types of congenital heart diseases (CHDs). Most ASDs occur sporadically, but some are inherited and associated with cardiac conduction defects such as atrioventricular block (AVB) or bundle branch block. Mutations in genes encoding transcription factor gene TBX5 and NKX2-5, were found in Holt-Oram syndrome (HOS) and ASD with atrioventricular (AV) conduction defects, respectively. HOS is characterized by upper limb anomaly in addition to ASD and AVB (heart-hand syndrome). ASD associated with NKX2-5 is rare but is reported to cause sudden cardiac death (SCD) or cardiomyopathy. We provide a review of these two diseases.

Overexpression of microRNA-1 causes atrioventricular block in rodents

The present study was designed to investigate whether microRNAs (miRNAs) are involved in atrioventricular block (AVB) in the setting of myocardial ischemia (MI). A cardiac-specific miR-1 transgenic (Tg) mouse model was successfully established for the first time in this study using microinjection. miR-1 level was measured by real-time qRT-PCR. Whole-cell patch clamp was employed to record L-type calcium current (I_Ca,L) and inward rectifier K⁺ current (I_K1). Expression of connexin 43 (Cx43) protein was determined by western blot analysis. Alternations of [Ca²⁺]_i was detected by laser scanning confocal microscopy in ventricular myocytes. The incidence of AVB was higher in miR-1 Tg mice than that in wild-type (WT) mice. The normalized peak current amplitude of I_Ca,L was lower in ventricular myocytes from miR-1 Tg mice as compared with WT mice. Similarly, the current density of I_K1 was decreased in miR-1 Tg mice than that in WT mice. Compared with WT mice, miR-1 Tg mice exhibited a significant decrease of the systolic [Ca²⁺]_i in ventricular myocytes but a prominent increase of the resting [Ca²⁺]_i. Moreover, Cx43 protein was downregulated in miR-1 Tg mice compared to that in WT mice. Administration of LNA-modified antimiR-1 reversed all the above changes. miR-1 overexpression may contribute to the increased susceptibility of the heart to AVB, which provides us novel insights into the molecular mechanisms underlying ischemic cardiac arrhythmias.