The impact of atrial fibrillation on prognosis in aortic stenosis

Background Atrial fibrillation (AF) and aortic stenosis (AS) are both highly prevalent and often coexist. Various studies have focused on the prognostic value of AF in patients with AS, but rarely considered left ventricular (LV) diastolic function as a prognostic factor. Objective To evaluate the prognostic impact of AF in patients with AS while correcting for LV diastolic function. Methods Patients with first diagnosis of significant AS were selected and stratified according to history of AF. The endpoint was all-cause mortality. Results In total, 2849 patients with significant AS (mean age 72 +/- 12 years, 54.8% men) were evaluated, and 686 (24.1%) had a history of AF. During a median follow-up of 60 (30-97) months, 1182 (41.5%) patients died. Ten-year mortality rate in patients with AF was 46.8% compared to 36.8% in patients with sinus rhythm (SR) (log-rank P < 0.001). On univariable (HR: 1.42; 95% CI: 1.25-1.62; P < 0.001) and multivariable Cox regression analysis (HR: 1.19; 95% CI: 1.02-1.38; P = 0.026), AF was independently associated with mortality. However, when correcting for indexed left atrial volume, E/e' or both, AF was no longer independently associated with all-cause mortality. Conclusion Patients with significant AS and AF have a reduced survival as compared to patients with SR. Nonetheless, when correcting for markers of LV diastolic function, AF was not independently associated with outcomes in patients with significant AS.Cardiolog

Detrimental immediate and medium-term clinical effects of right ventricular pacing in patients with myocardial fibrosis.

Background: Long-term right ventricular (RV) pacing leads to heart failure or a decline in left ventricular (LV) function in up to a fifth of patients. We aimed to establish whether patients with focal fibrosis detected on late gadolinium enhancement cardiovascular magnetic resonance (CMR) have deterioration in LV function after RV pacing. Methods: We recruited 84 patients with LV ejection fraction ≥40% into 2 observational CMR studies. Patients (n=34) with a dual-chamber device and preserved atrioventricular conduction underwent CMR in 2 asynchronous pacing modes (atrial asynchronous and dual-chamber asynchronous) to compare intrinsic atrioventricular conduction with forced RV pacing. Patients (n=50) with high-grade atrioventricular block underwent CMR before and 6 months after pacemaker implantation to investigate the medium-term effects of RV pacing. Results: The key findings were (1) initiation of RV pacing in patients with fibrosis, compared with those without, was associated with greater immediate changes in both LV end-systolic volume index (5.3±3.5 versus 2.1±2.4 mL/m2; P1.1 g of fibrosis with 90% sensitivity and 70% specificity. Conclusions: Fibrosis detected on CMR is associated with immediate- and medium-term deterioration in LV function following RV pacing and could be used to identify those at risk of heart failure before pacemaker implantation

Characteristics of Early-Onset vs Late-Onset Colorectal Cancer: A Review.

The incidence of early-onset colorectal cancer (younger than 50 years) is rising globally, the reasons for which are unclear. It appears to represent a unique disease process with different clinical, pathological, and molecular characteristics compared with late-onset colorectal cancer. Data on oncological outcomes are limited, and sensitivity to conventional neoadjuvant and adjuvant therapy regimens appear to be unknown. The purpose of this review is to summarize the available literature on early-onset colorectal cancer. Within the next decade, it is estimated that 1 in 10 colon cancers and 1 in 4 rectal cancers will be diagnosed in adults younger than 50 years. Potential risk factors include a Westernized diet, obesity, antibiotic usage, and alterations in the gut microbiome. Although genetic predisposition plays a role, most cases are sporadic. The full spectrum of germline and somatic sequence variations implicated remains unknown. Younger patients typically present with descending colonic or rectal cancer, advanced disease stage, and unfavorable histopathological features. Despite being more likely to receive neoadjuvant and adjuvant therapy, patients with early-onset disease demonstrate comparable oncological outcomes with their older counterparts. The clinicopathological features, underlying molecular profiles, and drivers of early-onset colorectal cancer differ from those of late-onset disease. Standardized, age-specific preventive, screening, diagnostic, and therapeutic strategies are required to optimize outcomes

Analytical landau-type model of polarization switching in ferroelectrics

The polarization switching properties of ferroelectric materials have been extensively studied, both experimentally and theoretically owing to their wide applications in industry and hence generating a need to gain a deeper understanding of factors affecting their switching behaviour. In this paper, an analytical Landau theory incorporating the Landau-Khalatnikov equation has been developed to describe the switching properties of second order ferroelectrics. Analytical expressions derived from exact results of Landau theory are used in modelling work carried out in this study for comparison with trends predicted by empirical laws used to describe polarization switching behaviour at high electric fields. As such this work has established the theoretical basis for empirical laws of polarization switching and developed simple numerical tools which can be quickly used to model trends in polarization switching behaviour of ferroelectrics. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Calculation of the parameters of the extended Hubbard Hamiltonian for superconducting copper oxides

10.1088/0953-8984/3/41/005Journal of Physics: Condensed Matter3418059-806

Calculation of the interaction parameters related to the Hubbard model

10.1103/PhysRevB.39.9200Physical Review B39139200-920

Two-temperature model for production of large-PT particles

10.1103/PhysRevD.30.1466Physical Review D3071466-146