Catheter ablation of atrial fibrillation in patients with left bundle branch block.

BACKGROUND: Left bundle branch block (LBBB) and atrial fibrillation (AF) are commonly coexisting conditions. The impact of LBBB on catheter ablation of AF has not been well determined. This study aims to explore the long-term outcomes of patients with AF and LBBB after catheter ablation. METHODS: Forty-two patients with LBBB of 11,752 patients who underwent catheter ablation of AF from 2011 to 2020 were enrolled as LBBB group. After propensity score matching in a 1:4 ratio, 168 AF patients without LBBB were enrolled as non-LBBB group. Late recurrence and a composite endpoint of stroke, all-cause mortality, and cardiovascular hospitalization were compared between the two groups. RESULTS: Late recurrence rate was significantly higher in the LBBB group than that in the non-LBBB group (54.8% vs. 31.5%, p = .034). Multivariate analysis showed that LBBB was an independent risk factor for late recurrence after catheter ablation of AF (hazard ratio [HR] 2.19, 95% confidence interval [CI] 1.09-4.40, p = .031). LBBB group was also associated with a significantly higher incidence of the composite endpoint (21.4% vs. 6.5%, HR 3.98, 95% CI 1.64-9.64, p = .002). CONCLUSIONS: LBBB was associated with a higher risk for late recurrence and a higher incidence of composite endpoint in the patients underwent catheter ablation.

Modeling of the Small-Scale Outbreak of COVID-19.

With the improvement of treatment and prevention methods, many countries have the pandemic under control. Different from the globally large-scale outbreak of COVID-19 in 2020, now the outbreak in these countries shows new characteristics, which calls for an effective epidemic model to describe the transmission dynamics. Meeting this need, first, we extensively investigate the small-scale outbreaks in different provinces of China and use classic compartmental models, which have been widely used in predictions, to forecast the outbreaks. Additionally, we further propose a new version of cellular automata with a time matrix, to simulate outbreaks. Finally, the experimental results show that the proposed cellular automata could effectively simulate the small-scale outbreak of COVID-19, which provides insights into the transmission dynamics of COVID-19 in China and help countries with small-scale outbreaks to determine and implement effective intervention measures. The countries with relatively small populations will also get useful information about the epidemic from our research.

Persistent Extracellular Signal-Regulated Kinase Activation by the Histamine H4 Receptor in Spinal Neurons Underlies Chronic Itch.

Transient extracellular signal-regulated kinase (ERK) activation in the spinal cord triggers histamine-induced acute itch. However, whether persistent ERK activation plays an important role in chronic itch development remains unclear. This study investigated the role of spinal ERK activation in chronic itch. The results showed that repetitive DNFB painting on the nape of mice evoked not only initial scratching but also sustained, spontaneous scratching. In addition, DNFB induced itching rather than nociception, as demonstrated using a cheek model. Furthermore, ERK was persistently activated in the spinal cord of DNFB-treated mice, and the intrathecal inhibition of phosphorylation of ERK suppressed both spontaneous itching and ERK activation. ERK activation was observed in neurons but not in glia cells during chronic itch development. Finally, DNFB-induced spontaneous itching behavior and ERK activation were largely inhibited by the histamine H4 receptor antagonist JNJ7777120 but not by the H1 receptor antagonist chlorpheniramine. Our results indicate that persistent ERK activation via the histamine H4 receptor in spinal neurons underlies DNFB-induced chronic itch.