Global left ventricular myocardial work efficiency in left bundle branch pacing versus right ventricular septal pacing: preliminary results of a randomized trial

Background

Recently, the concept of left bundle branch pacing (LBBP) has emerged in clinical practice, in an attempt to prevent the deteriorating effects of right ventricular pacing (Vp).

Purpose

The aim of this study is to compare the effect of Vp on left ventricular (LV) dyssynchrony in patients with atrioventricular block (AVB) and preserved ejection fraction (EF), subjected to either LBBP or right ventricular septal pacing (RVSP).

Methods

Patients with AVB are randomized 1:1 to LBBP or RVSP. The effect of Vp is evaluated by echocardiographic indices of dyssynchrony, such as global myocardial work efficiency (GWE) and peak systolic dispersion (PSD). GWE represents the ratio of constructive work divided by the sum of constructive and wasted work [1]. Successful LBBP is defined by the presence of right bundle branch block paced QRS morphology in lead V1 and stim to LV activation time <75 msec [2]. No back-up right Vp lead was used in LBBP group.

Results

We conducted a preliminary analysis of the first 20 patients. Enrollment is still ongoing and total follow-up period is one year. We sought to investigate the acute effect of Vp on LV dyssynchrony 24 hours post procedure. Patients' baseline characteristics were similar in both groups and are presented in Table 1.

One crossover was noted from LBBP to RVSP group, due to high ventricular capture threshold during implant. Implantation time was increased in LBBP arm (130±17.4 min in LBBP versus 47.7±4.5 min in RVSP group, p=0.004). Left bundle branch potential was recorded in 3 out of 10 LBBP patients. No statistically significant difference was demonstrated in GWE between the two groups (91.3% in LBBP versus 87.4% in RVSP group, p=0.052). PSD was numerically shorter in LBBP (53.3 msec) versus in RVSP (63.6 msec), p=0.114. There were no complications during both the acute perioperative phase and the running period of the follow-up. Moreover, no acute ventricular threshold capture rise, or lead dislodgement has been observed in neither group.

The increased implantation time may be attributed to the more demanding technique, or the learning curve period required in the arm of LBBP. In the present analysis, a remarkable difference regarding GWE in favor of the LBBP group was demonstrated, although statistically not significant. However, even in this initial phase of the study, there is a trend of better LV synchrony and less wasted myocardial work in the LBBP group. The final difference of these indices will be assessed at the end of the one-year follow-up, when comparative results will be available.

Conclusion

LBBP is a novel, safe pacing method. Despite the longer procedural time and the risk of crossover, LBBP seems to offer better – without however statistical significance – LV synchrony even in the acute postoperative phase compared to RVSP. Longer follow-up studies are required to test whether LBBP compared to RVSP confers substantial clinical benefit.

Funding Acknowledgement

Type of funding sources: None.

Multiomics Analysis Coupled with Text Mining Identify Novel Biomarker Candidates for Recurrent Cardiovascular Events

Recurrent cardiovascular events remain an enigma that accounts for >30% of deaths worldwide. While heredity and human genetics variation play a key role, host-environment interactions offer a sound conceptual framework to dissect the molecular basis of recurrent cardiovascular events from genes and proteins to metabolites, thus accounting for environmental contributions as well. We report here a multiomics systems science approach so as to map interindividual variability in susceptibility to recurrent cardiovascular events. First, we performed data and text mining through a mixed-methods content analysis to select genomic variants, 10 single nucleotide polymorphisms, and microRNAs (miR-10a, miR-21, and miR-20a), minimizing bias in candidate marker selection. Next, we validated our in silico data in a patient cohort suffering from recurrent cardiovascular events (a cross-sectional study design and sampling). Our findings report a key role in low-density lipoprotein clearance for rs11206510 (p < 0.01) and rs515135 (p < 0.05). miR-10a (p < 0.05) was significantly associated with heart failure, while increased expression levels for miR-21 and miR-20a associated with atherosclerosis. In addition, liquid chromatography-mass spectrometry-based (LC-MS-based) proteomics analyses identified that vascular diameter and cholesterol levels are among the key factors to be considered in recurrent cardiovascular events. From a methodology innovation standpoint, this study offers a strategy to enhance the signal-to-noise ratios in mapping novel biomarker candidates wherein each research and conceptual step were interrogated for their validity and in turn, enriched one another, ideally translating information growth to knowledge growth.

Inflammation and chronic heart failure: from biomarkers to novel anti-inflammatory therapeutic strategies

Heart failure (HF) is a complex heterogeneous syndrome with immune, metabolic and neurohumoral mechanisms interacting and leading to gradual heart contractility impairment. From the first study-to correlate inflammation with HF, inflammation biomarkers have been the subject of intense inquiry in patients with various forms of HF. Chronic HF (CHF) is strongly associated with inflammation in terms of pathogenesis, progression, severity and prognosis. Inflammatory mediators participate in CHF pathophysiology in various ways like exerting direct impact on cardiac myocytes, fibroblasts and β-adrenergic receptors leading to hypertrophy, fibrosis and impaired cardiac contractility, respectively, or inducing apoptosis by stimulation of the proper genes. The anti-inflammatory effects of classical heart failure therapeutic strategies such as ACEI and b-blockers are rather conflicting. Whether novel immunomodulating and anti-inflammatory therapeutic approaches should be added to existing therapies in order to ensure additional benefit to HF patients is under investigation. In this review, we summarize the pathophysiological link between inflammatory processes and CHF, focusing on the role of novel and traditional inflammatory biomarkers and highlighting novel anti-inflammatory therapeutic strategies.

Noonan syndrome and systemic lupus erythematosus in a patient with a novel KRAS mutation

Noonan syndrome is characterised by distinct facial stigmata, short stature and congenital cardiopathy. It has a high genetic heterogeneity and mutations in six different genes can be involved. We report a patient with Noonan syndrome and a novel KRAS mutation who presents systemic lupus erythematosus.

Tumor spectrum in children with Noonan syndrome and SOS1 or RAF1 mutations

Noonan syndrome (NS) is an autosomal dominant disorder caused by mutations in PTPN11, KRAS, SOS1, and RAF1. We performed SOS1, RAF1, BRAF, MEK1, and MEK2 mutation analysis in a cohort of 102 PTPN11- and KRAS-negative NS patients and found pathogenic SOS1 mutations in 10, RAF1 mutations in 4, and BRAF mutations in 2 patients. Three novel SOS1 mutations were found. One was classified as a rare benign variant and the other remains unclassified. We confirm a high prevalence of pulmonic stenosis and ectodermal abnormalities in SOS1-positive patients. Three patients with SOS1 mutations presented with tumors (embryonal rhabdomyosarcoma, Sertoli cell testis tumor, and granular cell tumors of the skin). One patient with a RAF1 mutation had a lesion suggestive for a giant cell tumor. This is the first report describing different tumor types in NS patients with germ line SOS1 mutations.