Effect of Atrial Pressure Increase on Effective Refractory Period and Vulnerability to Atrial Fibrillation in Patients with Lone Atrial Fibrillation

Background: There is evidence suggesting that atrial fibrillation (AF) may be induced by acute increase of atrial pressure. The aim of the present study was to investigate the effect of alterations in atrial pressure, induced by varying the atrioventricular (AV) interval, on atrial refractoriness, and on the frequency of induction of (AF), in patients with a history of lone atrial fibrillation (LAF).Methods and Results: Twenty-five patients were included in this study. The patients were divided in two groups: the LAF group, and the control group. None of the patients in either group had organic heart disease. Effective refractory period (ERP) and duration of atrial extrastimulus electrogram (A₂) were measured at two right atrial sites (high lateral wall, atrial appendage) during AV pacing (cycle length: 500 msec) with different AV intervals. Peak, minimal and mean atrial pressure increased from 8.57 ± 2.37 to 18.14 ± 4.74 mm Hg, 2 ± 2.23 to 5.14 ± 2.60 mm Hg (p = 0.0001) and from 4.28 ± 1.6 mm Hg to 9.77 ± 2.9 mm Hg (p = 0.001), respectively during AV interval modification. During lateral and atrial appendage pacing, with a progressive decrease of AV interval to 160, 100, 80, 40, 0 msec, the ERP, the dispersion of ERP, functional refractory period (FRP), A2 and latency period (LP) did not change significantly, in both groups. The frequency of induction of AF was not statistically different in both lateral atrial wall and appendage, during pacing in different AV intervals.Conclusions: This study demonstrates that alterations in the intraatrial pressure does not have important effects on atrial refractoriness and does not increase vulnerability to AF in patients with a history of LAF.     

Inhibition of adhesion of Clostridium difficile to human intestinal cells after treatment with serum and intestinal fluid isolated from mice immunized with nontoxigenic C. difficile membrane fraction

Diarrhea and pseudomembrane colitis caused by Clostridium difficile infection is a global health concern because of the high recurrence rate after standard antibiotic therapy. Vaccination presents a powerful countermeasure against disease recurrence. In this study, mice vaccinated with the nontoxigenic C. difficile membrane fraction generated a marked immune response to the antigen, as demonstrated by the serum IgG and intestinal fluid IgA levels. Significantly, pretreatment with harvested IgG- and IgA-containing fluids was sufficient to prevent in vitro adhesion of C. difficile to human Caco-2 intestinal cells. These results highlight the potential of nontoxigenic C. difficile membrane fraction as a vaccine candidate for C. difficile infection.     

Incident Heart Failure and Long-Term Risk for Venous Thromboembolism

BackgroundHeart failure (HF) hospitalization places patients at increased short-term risk for venous thromboembolism (VTE). Long-term risk for VTE associated with incident HF, HF subtypes, or structural heart disease is unknown.ObjectivesIn the ARIC (Atherosclerosis Risk In Communities) cohort, VTE risk associated with incident HF, HF subtypes, and abnormal echocardiographic measures in the absence of clinical HF was assessed.MethodsDuring follow-up, ARIC identified incident HF and subcategorized HF with preserved ejection fraction or reduced ejection fraction. At the fifth clinical examination, echocardiography was performed. Physicians adjudicated incident VTE using hospital records. Adjusted Cox proportional hazards models were used to evaluate the association between HF or echocardiographic exposures and VTE.ResultsOver a mean of 22 years in 13,728 subjects, of whom 2,696 (20%) developed incident HF, 729 subsequent VTE events were identified. HF was associated with increased long-term risk for VTE (adjusted hazard ratio: 3.13; 95% confidence interval: 2.58 to 3.80). In 7,588 subjects followed for a mean of 10 years, the risk for VTE was similar for HF with preserved ejection fraction (adjusted hazard ratio: 4.71; 95% CI: 2.94 to 7.52) and HF with reduced ejection fraction (adjusted hazard ratio: 5.53; 95% confidence interval: 3.42 to 8.94). In 5,438 subjects without HF followed for a mean of 3.5 years, left ventricular relative wall thickness and mean left ventricular wall thickness were independent predictors of VTE.ConclusionsIn this prospective population-based study, incident hospitalized HF (including both heart failure with preserved ejection fraction and reduced ejection fraction), as well as echocardiographic indicators of left ventricular remodeling, were associated with greatly increased risk for VTE, which persisted through long-term follow-up. Evidence-based strategies to prevent long-term VTE in patients with HF, beyond time of hospitalization, are needed.     

Development of a Risk Score Based on Aortic Calcification to Predict 1-Year Mortality After Transcatheter Aortic Valve Replacement

Objectives

The aim of this study was to develop a new scoring system based on thoracic aortic calcification (TAC) to predict 1-year cardiovascular and all-cause mortality.

Effect of digoxin in patients with heart failure and mid‐range (borderline) left ventricular ejection fraction

Aims

To evaluate the effects of digoxin in patients with the newly described phenotype of heart failure (HF) and mid‐range ejection fraction (HFmrEF), attributed to mild left ventricular systolic dysfunction.

Methods and results

We carried out a retrospective analysis of the Digitalis Investigation Group (DIG) trial which had 7788 patients available for analysis with a left ventricular ejection fraction (LVEF) ranging between 3% and 85%. We compared the effect of digoxin to placebo in three mutually exclusive groups of patients defined by LVEF category: <40% (HF with reduced LVEF, HFrEF, n = 5874), 40–49% (HFmrEF, n = 1195) and ≥50% (HF with preserved LVEF, HFpEF, n = 719). The primary outcome was the composite of cardiovascular death or HF hospitalisation. Patients with HFmrEF resembled patients with HFrEF, more than those with HFpEF, with respect to age, sex and aetiology but were more like HFpEF patients with respect to blood pressure and the prevalence of hypertension. Event rates in patients with HFmrEF were similar to those in HFpEF and much lower than in HFrEF. Digoxin reduced the primary endpoint in patients with HFrEF, mainly due to reduced HF hospitalisation: the digoxin/placebo hazard ratio (HR) for HF hospitalisation was 0.71 [95% confidence interval (CI) 0.65–0.77]. The digoxin/placebo HR for HF hospitalisation in patients with HFmrEF was 0.80 (95% CI 0.63–1.03) and 0.85 (95% CI 0.62–1.17) in those with HFpEF. The digoxin/placebo HR for the composite of HF death or HF hospitalisation was 0.74 (95% CI 0.68–0.81) in HFrEF, 0.83 (95% CI 0.66–1.05) in HFmrEF and 0.88 (95% CI 0.65–1.19) in HFpEF.

Conclusions

In this study, event rates in patients with HFmrEF were closer to those in HFpEF than HFrEF. Digoxin had most effect on HF hospitalisation in patients with HFrEF, an intermediate effect in HFmrEF, and the smallest effect in HFpEF.

     

Propensity-Matched 1-Year Outcomes Following Transcatheter Aortic Valve Replacement in Low-Risk Bicuspid and Tricuspid Patients

ObjectivesThe aim of this study was to compare 1-year outcomes after transcatheter aortic valve replacement (TAVR) in low surgical risk patients with bicuspid aortic stenosis to patients with tricuspid aortic stenosis.BackgroundThe pivotal TAVR trials excluded patients with bicuspid aortic valves. The Low Risk Bicuspid Study 30-day primary endpoint of death or disabling stroke was 1.3%.MethodsThe Low Risk Bicuspid Study is a prospective, single-arm, TAVR trial that enrolled patients from 25 U.S. sites. A screening committee confirmed bicuspid anatomy and valve classification on computed tomography using the Sievers classification. Valve sizing was by annular measurements. An independent clinical events committee adjudicated all serious adverse events, and an independent core laboratory assessed all echocardiograms. The 150 patients from the Low Risk Bicuspid Study were propensity matched to the TAVR patients in the randomized Evolut Low Risk Trial using the 1:1 5- to-1-digit greedy method, resulting in 145 pairs.ResultsAll-cause mortality or disabling stroke at 1 year was 1.4% in the bicuspid and 2.8% in the tricuspid group (P = 0.413). A pacemaker was implanted in 16.6% of bicuspid and 17.9% of tricuspid patients (P = 0.741). The effective orifice area was similar between groups at 1 year (2.2 ± 0.7 cm² vs 2.3 ± 0.6 cm², P = 0.677) as was the mean gradient (8.7 ± 3.9 mm Hg vs 8.5 ± 3.1 mm Hg, P = 0.754). Fewer patients in the bicuspid group had mild or worse paravalvular leak (21.3% vs 42.6%, P < 0.001).ConclusionsThere were no significant differences in clinical or forward flow hemodynamic outcomes between the propensity-matched groups at 1 year.     

Age-Related Outcomes After Transcatheter Mitral Valve Repair in Patients With Heart Failure: Analysis From COAPT

ObjectivesThe aim of this study was to assess the impact of age on outcomes in patients undergoing transcatheter edge-to-edge repair (TEER) from the COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation) trial.BackgroundIn the COAPT trial, TEER with the MitraClip device in patients with heart failure (HF) and moderate to severe or severe secondary mitral regurgitation (SMR) reduced the risk for HF hospitalization (HFH) and all-cause mortality compared with maximally tolerated guideline-directed medical therapy (GDMT) alone. There are limited data regarding the effectiveness of MitraClip therapy in elderly patients.MethodsPatients (n = 614) were grouped by median age at randomization (74 years) and by MitraClip treatment vs GDMT alone. The primary endpoint was the 2-year rate of death or HFH assessed by multivariable Cox regression.ResultsDeath or HFH within 2 years occurred less frequently after treatment with the MitraClip vs GDMT alone in patients <74 years of age (37.3% vs 64.5%; adjusted HR: 0.41; 95% CI: 0.29-0.59) and ≥74 years of age (51.7% vs 69.6%; adjusted HR: 0.58; 95% CI: 0.42-0.81) (P_int = 0.17). Mortality was also consistently reduced with MitraClip treatment in young and elderly patients (P_int = 0.42). In contrast, elderly patients treated with the MitraClip vs GDMT alone tended to have a lesser reduction of HFH than younger patients (P_int = 0.03). Younger and older patients had similar improvements in quality of life after treatment with the MitraClip compared with GDMT alone.ConclusionsIn the COAPT trial, MitraClip treatment of moderate to severe and severe SMR reduced the composite risk for death or HFH and improved survival and quality of life regardless of age. As such, young and elderly patients with HF and severe SMR benefit from TEER, although elderly patients may not have as great a benefit from the MitraClip device in reducing HFH.     

深部调驱增油量新概念

目前国内深部调驱效果评价体系尚未成熟,现用增油量概念难以理解,而且混乱、定义不明确。提出两个简明易懂的增油量新概念—视增油和真实增油,并给出相应的定义和计算方法。同时,以塔里木油田深部调驱的油井为例,分析、计算了其视增油与真实增油,评价结果可靠,并认为这两个概念对于规范深部调驱增油效果计算、建立评价体系及现场应用都有帮助。