Yanmin Xu

Atrial remodeling: New pathophysiological mechanism of atrial fibrillation

Atrial fibrillation (AF), the most common sustained arrhythmia associated with substantial cardiovascular morbidity and mortality with stroke being the most critical complication. Most frequently, AF occurs in conjunction with other cardiovascular disease, such as hypertension, ischemic heart disease, valve disease or cardiac failure. Role of atrial remodeling has emerged as the new pathophysiological mechanism of atrial fibrillation. Experimental and clinical studies point at two major mechanisms involved in the intrinsically progressive nature of AF. The first consists of a change in the electrical properties of the atrium, notably a shortening of the AERP and a loss of rate adaptation, and hence was named electrical remodeling. Furthermore, based on data from is experimental models, it has been considered that AF is also associated with elaborate adaptive and maladaptive changes in tissue and cellular architecture. By parallel, this type of change was denominated structural remodeling. Together, these mechanisms will increase the probability of generating multiple atrial wavelets by enabling rapid atrial activation and dispersion of refractoriness.

Probucol for the prevention of cystatin C-based contrast-induced acute kidney injury following primary or urgent angioplasty: a randomized, controlled trial.

BACKGROUND Probucol, a lipid-lowering drug with potent antioxidant properties, may reduce the risk of cystatin C (CyC)-based contrast-induced acute kidney injury (CIAKI). The aim of this study was to observe the incidence of CyC-based CIAKI and assess the efficacy of probucol on prevention of CIAKI following primary or urgent coronary angioplasty. METHODS A total of 204 patients with acute coronary syndrome (ACS) were prospectively randomized to a control group (108 patients, 74 male, 65.4 ± 12.5 years) or probucol group (96 patients, 67 male, 65.1 ± 10.5 years) 1000 mg orally before primary or urgent angioplasty and 500 mg twice daily for 3 days following intervention. Serum CyC and serum creatinine (Scr) concentrations were measured before, and on day 1, day 2 and day 3 after coronary intervention. RESULTS The clinical characteristics of the patients from the two groups were similar. Scr-based CIAKI was developed in 23 patients of the control group (21.3%) and in 4 patients of the probucol group (4.2%) (P<0.001). Furthermore, CyC-based CIAKI occurred in 56 patients of the control group (51.9%) and 28 patients of the probucol group (29.2%) (P<0.001). The CyC increase ≥ 10% after exposure to contrast medium was the best increment cutoff value for the early identification of patients at risk of CIAKI. CONCLUSIONS Our study suggests that CyC is a reliable marker for early identification and ruling out the patients at the risk of CIAKI. Among the patients with ACS who are undergoing primary or urgent angioplasty, prophylactic treatment with probucol reduces the risk of both Scr and CyC-based CIAKI.

Atrial Remodeling in Atrial Fibrillation and Some Related MicroRNAs

Atrial fibrillation is the most common sustained arrhythmia associated with substantial cardiovascular morbidity and mortality, with stroke being the most critical complication. The role of atrial remodeling has emerged as the new pathophysiological mechanism of atrial fibrillation. Electrical remodeling and structural remodeling will increase the probability of generating multiple atrial wavelets by enabling rapid atrial activation and dispersion of refractoriness. MicroRNAs (miRNAs) are small non-coding RNAs of 20–25 nucleotides in length that regulate expression of target genes through sequence-specific hybridization to the 3’ untranslated region of messenger RNAs and either block translation or direct degradation of their target messenger RNA. They have also been implicated in a variety of pathological conditions, such as arrhythmogenesis and atrial fibrillation. Target genes of miRNAs have the potential to affect atrial fibrillation vulnerability.

Atrial fibrillation: recent advances in understanding the role of microRNAs in atrial remodeling with an electrophysiological overview.

Atrial fibrillation (AF) is a highly prevalent condition associated with pronounced cardiovascular-related morbidity, mortality and socioeconomic burden. It accounts for more hospitalization days than does any other arrhythmia. This article reviews the basic electrophysiology of AF, electrical and structural remodeling in AF and recent advances in understanding the molecular mechanisms of AF in relation to specific microRNAs. This paper also reviews the potential role of microRNAs as novel therapeutic targets as well as biomarkers in the management of AF. AF shows characteristics typical of altered electrophysiology that promote ectopic activity and facilitate reentry, thereby contributing to the progression from short paroxysmal AF to a persistent, permanent form via atrial remodeling, even in the absence of progressive underlying heart disease. MicroRNAs have been suggested to influence the development of AF by regulating gene expression at the post-transcriptional level. Increasing evidence has identified various microRNA modifications and their impacts on AF initiation and maintenance through electrical and structural remodeling. The discovery of specific microRNAs as novel therapeutic targets and some experimental evidence implicating microRNAs as potential molecular diagnostic markers have had a significant impact on the diagnosis and management of AF and demand further research.

The role of Toll-like receptor 2 and hypoxia-induced transcription factor-1α in the atrial structural remodeling of non-valvular atrial fibrillation

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Fragmented QRS complexes have predictive value of imperfect ST-segment resolution in patients with STEMI after primary percutaneous coronary intervention.

OBJECTIVES To investigate the clinical characteristics of patients with the fragmented QRS complexes (fQRS) and the predictive value of fQRS in patients undergoing primary percutaneous coronary intervention (p-PCI). METHODS The study enrolled 227 consecutive patients with ST-elevation myocardial infarction who underwent p-PCI. Baseline clinical characteristics, the percentage of ST-segment resolution, and parameters of electrocardiography and coronary angiography were investigated. The relationship between fQRS on pre-PCI and post-PCI electrocardiogram and the percentage of ST-segment resolution after PCI were studied. RESULTS Patients with fQRS have higher troponin I, creatine kinase-MB levels, prolonged QRS duration, higher Gensini score, lower percentage of total ST-segment resolution, and left ventricular ejection fraction compared with patients without fQRS. Gensini score (odds ratio [OR], 1.013; 95% confidence interval [CI], 1.002-1.024; P < .006) and percentage of total ST-segment resolution (OR, 0.384; 95% CI, 0.186-0.795; P = .01) were independently associated with the presence of fQRS. A multivariate logistic regression analysis selected presence of fQRS pre-PCI (OR, 2.908; 95% CI, 1.095-7.723; P = .032) and the number of leads with fQRS before PCI (OR, 1.582; 95% CI, 1.250-2.002; P < .001) as independent predictors of imperfect ST-segment resolution. CONCLUSIONS The presence of fQRS is a predictor in ST-elevation myocardial infarction patients undergoing p-PCI. The occurrence of fQRS is beneficial to identify the patients with severe coronary lesion, left ventricular contraction dysfunction, and larger areas of ischemic injury.

The risk factors of the permanent pacemaker implantation in patients with postoperative delirium

outlines old age (OR, 1.038, 95% CI: 1.00–1.077, P = 0.048), low birth weight (OR, 0.907, 95% CI: 0.879–0.935, P b 0.001), cardiac care unit (OR, 3.372,95% CI: 1.589–7.153, P = 0.002) as the independent risk fac

THE RELATIONSHIP BETWEEN SERUM 25-HYDROXYITAMIN D AND ACUTE CORONARY SYNDROME

Objectives to study the relationship between serum 25-hydroxyitamin D and acute coronary syndrome. Methods 71 patients whom conform to standard were chosen from Apr 2011 to June 2011 in the second hospital of Tianjin Medical University.18 cases were acute myocardial infarction,16 cases were unstable angina, 23 cases were stable angina,14 cases were control group. The level of 25-hydroxy Vitamin, mmp-9, Tlr-4 in serum were measured by ELISA in every group. The correlation between serum 25-hydroxyitamin D and mmp-9, TLR-4 were analysed. Results The serum level of 25- hydroxyitamin D was significantly lower in ACS group than in SAP group, control group p<0.01). No significantly different was found between SAP group and control group. A negative correlation was found between the level of 25-hydroxyitamin D and mmp-9, Tlr-4. Conclusions serum 25-hydroxyitamin D play an important role in the development of ACS and have native relationship with mm-9-, Tlr-4.

THE RELATIONSHIP BETWEEN TLR2, HIF-1α, MMP-9 WITH THE OCCURRENCE AND MAINTENANCE OF ATRIAL FIBRILLATION

Objectives To discuss the relation between TLR2, HIF-1α, MMP-9 as immunological and inflammatory factor in the occurrence and maintenance of atrial fibrillation. Methods 57 cases of atrial fibrillation were chosen, 20 cases were paroxysmal atrial fibrillation and 22 cases were persistent atrial fibrillation and 15 cases were permanent atrial fibrillation, 23 sinus rhythm cases were also selected into the control group. TLR2, HIF-1α, MMP-9 levels of each group were compared and left atrial diameter and LVEF were measured, respectively. Results TLR2 level of permanent atrial fibrillation group was significantly higher than that of the other three groups (p<0.05) and the level of persistent atrial fibrillation group was significantly higher than that of paroxysmal atrial fibrillation and control group (p<0.05), the level between paroxysmal atrial fibrillation and control group has no difference (p>0.05). The MMP-9 level of permanent atrial fibrillation group was significantly higher than that of the other three groups (p<0.05) and the level of persistent atrial fibrillation group was significantly higher than that of paroxysmal atrial fibrillation and control group (p<0.05), the level between paroxysmal atrial fibrillation and control group has no difference (p>0.05). The HIF-1α levels of permanent atrial fibrillation group and persistent atrial fibrillation group was significantly higher than that of the other two groups (p<0.05), the level between permanent atrial fibrillation group and persistent atrial fibrillation group has no difference (p>0.05), the level between paroxysmal atrial fibrillation and control group has no difference (p>0.05). Compared with left atrial diameter of the other three groups, that of the permanent atrial fibrillation group increased significantly. Compared with left atrial diameter of paroxysmal atrial fibrillation and control group that of the persistent atrial fibrillation group increased significantly. The left atrial diameter of paroxysmal atrial fibrillation higher than that of the control group (p<0.05). However, the LVEF decreased significantly in the atrial fibrillation groups (p<0.05). The LVEF between atrial fibrillation groups has no difference (p>0.05) between persistent and permanent atrial fibrillation group, there is a positive correlation between the TLR2, HIF-1α, MMP-9 levels and left atrial diameter, but there is a negative correlation between the levels and LVEF. Conclusions The increase of TLR2、HIF-1α, MMP-9 level probably participates in occurrence of atrial fibrillation, thus it indicates that the inflammatory reaction may promote the occurrence and maintenance of atrial fibrillation.