Validation of E/e' Using the Index-Beat Method as an Estimate of Left Atrial Pressure in Patients with Atrial Fibrillation.

INTRODUCTION: Echocardiographic assessment of diastolic function during atrial fibrillation (AF) remains challenging due to the irregular cardiac cycle length. We sought to assess whether the index-beat method, the beat following two preceding cardiac cycles of equal duration, could provide a more reliable measurement of E/e' (mitral E wave/diastolic tissue Doppler velocity) than the conventional averaging of consecutive beats and hence facilitate the noninvasive estimation of elevated left atrial pressure (LAP) in patients with AF. METHODS: We prospectively studied 35 patients with persistent AF who had preserved left ventricular ejection fraction and underwent radiofrequency ablation. LAP was measured in conjunction with transseptal puncture during catheter ablation. Echocardiography was performed 24 h before ablation and E/e' was determined using the recommended averaging of 10 beats and the index-beat method, with the observers blinded to the clinical details and LAP measurements. RESULTS: Correlation analysis showed a strong positive correlation between two methods in terms of both septal E/e' (r = 0.841, p < 0.001) and lateral E/e' (r = 0.930, p < 0.001). Bland-Altman analysis also showed a good agreement between the two measurement methods in terms of E/e'. E/e' determined using both conventional averaging and the index-beat method was significantly correlated with LAP (p < 0.05). After Fisher Z transformation, we found that the index-beat septal E/e' had a better correlation with LAP than did the conventional averaging E/e' (r = 0.736 vs. r = 0.392, Zr = -2.110, p = 0.035). Furthermore, the index-beat method took significantly less time to measure E/e' (mean 33.6 s; 95% confidence intervals [CIs]: 32.1 s-36.2 s) than did conventional averaging method (mean 96.2 s; 95% CI: 90.2 s-102.3 s; p < 0.001). Receiver operating characteristic curve analysis revealed that the optimal cut-off for predicting mean LAP >12 mm Hg was 11 (sensitivity 100%; specificity 77.3%) for index-beat septal E/e' and 16 (sensitivity 61.5%; specificity 95.5%) for index-beat lateral E/e'. CONCLUSIONS: Good correlations were found between E/e' and LAP in patients with AF, particularly with the index-beat method. Moreover, the index-beat method can easily measure E/e' at an accuracy similar to that for the conventional averaging of consecutive beats, which can therefore be applied to assess the diastolic dysfunction and potentially improve the diagnosis of heart failure in patients with AF.

Successful non-operative management of atrioesophageal fistula after combined therapy of catheter ablation and left atrial appendage closure for atrial fibrillation: A case report.

Atrioesophageal fistula (AEF) is a rare but devastating complication of radiofrequency ablation (RFCA) for atrial fibrillation (AF) and is associated with high mortality rates. Whereas most cases of AEF are treated by emergency surgical interventions, we report a case of paroxysmal AF with AEF after combined therapy of catheter ablation and percutaneous left atrial appendage closure (LAAC), which was treated successfuly without major surgery or esophageal stenting. He was presented 18 days after the procedure, suffering chest pain, fever, and a transient loss of consciousness. Computed tomography (CT) of the chest disclosed a small accumulation of air in the region of the left atrium adjacent to the esophagus, suggesting AEF. Supported by early aggressive antibiotic therapy, pericardial drainage and a fasting state with adequate parenteral nutrition, resulted in improvement of his condition with no recurrence of symptoms. Subsequent chest CT scans confirmed disappearance of the leaked air and the patient was discharged home 28 days after admission with no neurological compromise. Early detection, rapid treatment and constant awareness of potential fatal consequences are prerequisites for successful treatment of this complication and prevention of fatal outcome.

Elevated CO2 does not stimulate carbon sink in a semi-arid grassland.

Elevated CO2 is widely accepted to enhance terrestrial carbon sink, especially in arid and semi-arid regions. However, great uncertainties exist for the CO2 fertilisation effects, particularly when its interactions with other global change factors are considered. A four-factor (CO2 , temperature, precipitation and nitrogen) experiment revealed that elevated CO2 did not affect either gross ecosystem productivity or ecosystem respiration, and consequently resulted in no changes of net ecosystem productivity in a semi-arid grassland despite whether temperature, precipitation and nitrogen were elevated or not. The observations could be primarily attributable to the offset of ecosystem carbon uptake by enhanced soil carbon release under CO2 enrichment. Our findings indicate that arid and semi-arid ecosystems may not be sensitive to CO2 enrichment as previously expected and highlight the urgent need to incorporate this mechanism into most IPCC carbon-cycle models for convincing projection of terrestrial carbon sink and its feedback to climate change.

[Meta-analysis of the combination of warfarin and clopidogrel after coronary stenting in patients with indications for chronic oral anticoagulation].

OBJECTIVE: To investigate the safety and efficacy of dual antithrombotic regimen of warfarin and clopidogrel in patients who underwent coronary stenting and were with chronic oral anticoagulation. METHODS: Two investigators independently searched Pubmed, Embase and Cochrane for all reported studies, and yielding 6 articles, published before April 2015, enrolling 4 825 patients, follow-up for at least 12 months. Two investigators independently recorded the data regarding interventions and the occurrence of major bleeding, ischemic stroke, myocardial infarction and death. RevMan5.3 was used to do analysis. RESULTS: Patients on dual antithrombotic regimen had insignificant reduction in major bleeding (odds ratio[OR]was 0.73, 95% confidence interval[CI]was from 0.46 to 1.14, and P=0.16) as compared with triple therapy. While the risk of ischemic stroke (OR= 0.78, 95%CI:0.44-1.38, P=0.39), myocardial infarction (OR= 1.19, 95%CI:0.92-1.53, P=0.18) and the overall incidence of death (OR=0.95, 95%CI:0.56-1.60, P=0.84) were also comparable between the two regimens. CONCLUSION: Dual antithrombotic regimen of warfarin and clopidogrel is comparable to the recommended triple therapy in respect to the prevention of thromboembolic outcomes of MI/ death and ischemic stroke, while the risk of bleeding is similar in those patients with indications for chronic oral anticoagulation undergoing percutaneous coronary intervention with stent implantation.

[Research progress on pharmacotherapy of calcific aortic valve disease].

With the population aging and declining incidence of rheumatic heart disease, calcific aortic valve disease (CAVD) has become the most frequent valve disease and the common cause of aortic valve replacement. Patients with CAVD need to cope with a deteriorating quality of life and valve replacement is the only effective clinical option for the patients. Therefore, early pharmacotherapy is of great significance in prevention or slow-down of the progression of CAVD. For years CAVD was considered to be a passive wear and tear process of valves, but now it is recognized as an active and multi-factorial process. Histopathologic studies have revealed that inflammation, disorder of calcium and phosphorus metabolism and dyslipidemia are involved in the process of CAVD. Clinical trials of CAVD pharmacotherapy have been carried out based on those histopathologic studies. Statin, renin-angiotensin inhibitors and anti-osteoporosis drug are well studied in recent years. This article reviews the recent research progress of the pharmacotherapy for CAVD.

Relationship between left ventricular diastolic function and the risk of left atrial appendage thrombus in patients with nonvalvular atrial fibrillation.

In patients with nonvalvular atrial fibrillation (NVAF), the impact of left ventricular diastolic function on the risk of left atrial appendage (LAA) thrombus has rarely been studied. This prospective study aimed to investigate the relationship between diastolic function and the risk of LAA thrombus in patients with NVAF. Seventy-six patients with NVAF admitted to receive radiofrequency catheter ablation were prospectively enrolled. All the patients underwent transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in 24 h before ablation. Diastolic function was estimated by TTE including left atrial volume index (LAVI) and E/e', as well as invasive left atrial pressure (LAP) measured during the ablation procedure. LAA peak emptying velocity (LAA-PEV) and the intensity of spontaneous echo contrast (SEC) were determined by TEE. Average E/e', LAVI and mean LAP had a significant positive correlation with the intensity of SEC, the coefficient of correlation were 0.344 (p = 0.002), 0.416 (p < 0.001) and 0.402 (p < 0.001), respectively. After adjustment for CHA2DS2-VASc score and type of AF, multivariate regression analysis revealed that increased LAP (OR 1.144, 95% CI 1.012-1.293, p = 0.031) independently correlated with the risk of LAA thrombus (SEC ≥ Grade 2). LAA-PEV showed a significantly inverse relationship with mean LAP in patients with AF (r = - 0.525, p < 0.001), and in the assessment of elevated LAP with TEE, the LAA-PEV cut-off of 0.40 m/s had a sensitivity of 80%, specificity of 81%. Left ventricular diastolic dysfunction may constitute a potential risk for LAA thrombus and stroke. Furthermore, evaluation of LAA emptying with use of TEE is helpful for assessing the LAP status of patients with AF.

The effect of beta-blockers on mortality in patients with heart failure and atrial fibrillation: A meta-analysis of observational cohort and randomized controlled studies.

BACKGROUND: Beta-blockers (BB) are the cornerstone of therapy for heart failure (HF); however, the effects of these drugs on the prognosis of patients with concomitant atrial fibrillation (AF) remain controversial. The objective of this meta-analysis was to evaluate the efficacy of BB on mortality in HF coexisting with AF. METHODS: A systematic search of PubMed, Embase and the Cochrane Library databases was conducted. Observational cohort studies and randomized controlled trials reporting outcomes of mortality or HF hospitalizations for patients with HF and AF, being assigned to BB treatment. A non-BB group was also included. RESULTS: A total of 8 clinical studies (5 randomized controlled trials and 3 observational cohort studies) involving 34197 patients were included in the analysis. The pooled analysis demonstrated that BB treatment was associated with a 22% reduction in relative risk of all-cause mortality in patients with HF and AF (RR: 0.78; 95% CI 0.71-0.86; p < 0.00001; I2 = 27%). The pooled analysis of 5 studies reported the outcome of HF hospitalization (2774 patients) which showed that BB therapy was not associated with a reduction of HF hospitalizations (RR: 0.94; 95% CI 0.79-1.11; p = 0.46; I2 = 38%). CONCLUSIONS: Meta-analysis suggests the potential mortality benefit of BB in patients with HF and AF. It was concluded herein that it is premature to deny patients with AF and HF to receive BB therapy considering current evidence.

A meta-analysis of 1,119 manipulative experiments on terrestrial carbon-cycling responses to global change.

Direct quantification of terrestrial biosphere responses to global change is crucial for projections of future climate change in Earth system models. Here, we synthesized ecosystem carbon-cycling data from 1,119 experiments performed over the past four decades concerning changes in temperature, precipitation, CO2 and nitrogen across major terrestrial vegetation types of the world. Most experiments manipulated single rather than multiple global change drivers in temperate ecosystems of the USA, Europe and China. The magnitudes of warming and elevated CO2 treatments were consistent with the ranges of future projections, whereas those of precipitation changes and nitrogen inputs often exceeded the projected ranges. Increases in global change drivers consistently accelerated, but decreased precipitation slowed down carbon-cycle processes. Nonlinear (including synergistic and antagonistic) effects among global change drivers were rare. Belowground carbon allocation responded negatively to increased precipitation and nitrogen addition and positively to decreased precipitation and elevated CO2. The sensitivities of carbon variables to multiple global change drivers depended on the background climate and ecosystem condition, suggesting that Earth system models should be evaluated using site-specific conditions for best uses of this large dataset. Together, this synthesis underscores an urgent need to explore the interactions among multiple global change drivers in underrepresented regions such as semi-arid ecosystems, forests in the tropics and subtropics, and Arctic tundra when forecasting future terrestrial carbon-climate feedback.

Effects of nitrogen addition and mowing on rodent damage in an Inner Mongolian steppe.

Rodent damage is a serious threat to sustainable management of grassland. The effects of nitrogen (N) deposition and grassland management on rodent damage have been scarcely studied. Here, we reported the effects of 2 years of N addition and mowing on burrow density and damage area of Citellus dauricus in a semiarid steppe in Inner Mongolia. N addition significantly aggravated, while mowing alleviated rodent damage in the grassland under study. Burrow density and damage area increased 2.8-fold and 4.7-fold, in N addition plots compared to the ambient N addition treatment, respectively. Conversely, mowing decreased burrow density and damage area by 75.9% and 14.5%, respectively, compared to no mowing plots. Observed changes in rodent damage were mainly due to variations in plant community cover, height, and aboveground net primary productivity. Our findings demonstrate that N addition and mowing can affect the rodent density and activity in grassland, suggesting that the effects of a changing atmospheric composition and land use on rodent damage must be considered in order to achieve better grassland management.