Comparison of clinical outcomes of Ibutilide-guided cardioversion and direct current synchronized cardioversion after radiofrequency ablation of persistent atrial fibrillation.

Backgroup: Ibutilide has already been used for cardioversion of persistent atrial fibrillation (PsAF) after radiofrequency catheter ablation (RFCA). The purpose of this study was to determine the effect of Ibutilide-guided cardioversion on clinical outcomes after individualized ablation of PsAF. Methods: From October 2020 to September 2021, consecutive patients with PsAF accepted for RFCA were prospectively enrolled. After individualized ablation including pulmonary vein isolation plus left atrial roof line ablation and personalized linear ablation based on left atrial low-voltage zones, patients were divided into the spontaneous conversion (SCV) group, direct current synchronized cardioversion (DCC) group and Ibutilide group according to different cardioversion types during ablation. The rates of freedom from atrial tachyarrhythmia (ATT) among the three groups were evaluated after follow-up. Results: In this study, 110 patients were enrolled, including 12 patients with SCV, 50 patients receiving DCC and 48 patients receiving Ibutilide cardioversion after individualized ablation. Among the three groups, the SCV group had shorter AF duration {12 months [interquartile range (IQR) 12-16], P = 0.042} and smaller left atrial diameter (LAD) [35 mm (IQR: 33-42), P = 0.023]. A 12-month freedom from ATT rate was 83.3% in SCV group, 69.4% in DCC group, and 79.2% in Ibutilide group, respectively (Log-rank, P = 0.745). During the follow-up [17 months (IQR: 15-19)], the rate of freedom from ATT of SCV group (83.3%), and Ibutilide group (72.9%) were both higher than that of DCC group (53.1%, P = 0.042). Moreover, Kaplan-Meier analysis showed a significantly higher sinus rhythm (SR) maintenance in Ibutilide group than in DCC group (Log-rank, P = 0.041). After adjusting for risk factors of AF recurrence, the hazard ratio for AF recurrence of the DCC group with reference to the Ibutilide group was 4.10 [95% confidence interval (CI) (1.87-8.98), P < 0.001]. Furthermore, subgroup analysis showed that freedom from ATT rate in effective Ibutilide subgroup was significantly higher than noneffective Ibutilide subgroup (Log-rank, P < 0.001). Conclusion: For the treatment of the patients with PsAF, Ibutilide-guided cardioversion after individualized RFCA may be benefit for maintenance of SR compared to conventional DCC, especially for the patients who are effective for administration of Ibutilide.

Construction and integrated analysis of the ceRNA network hsa_circ_0000672/miR-516a-5p/TRAF6 and its potential function in atrial fibrillation.

Atrial fibrosis is a crucial contributor to initiation and perpetuation of atrial fibrillation (AF). This study aimed to identify a circRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) regulatory network related to atrial fibrosis in AF, especially to validate hsa_circ_0000672/hsa_miR-516a-5p/TRAF6 ceRNA axis in AF preliminarily. The circRNA-miRNA-mRNA ceRNA network associated with AF fibrosis was constructed using bioinformatic tools and literature reviews. Left atrium (LA) low voltage was used to represent LA fibrosis by using LA voltage matrix mapping. Ten controls with sinus rhythm (SR), and 20 patients with persistent AF including 12 patients with LA low voltage and 8 patients with LA normal voltage were enrolled in this study. The ceRNA regulatory network associated with atrial fibrosis was successfully constructed, which included up-regulated hsa_circ_0000672 and hsa_circ_0003916, down-regulated miR-516a-5p and five up-regulated hub genes (KRAS, SMAD2, TRAF6, MAPK11 and SMURF1). In addition, according to the results of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, these hub genes were clustered in TGF-beta and MAPK signaling pathway. In the patients with persistent AF, hsa_circ_0000672 expression in peripheral blood monocytes was significantly higher than those in controls with SR by quantitative real-time polymerase chain reaction (p-value < 0.001). Furthermore, hsa_circ_0000672 expression was higher in peripheral blood monocytes of persistent AF patients with LA low voltage than those with LA normal voltage (p-value = 0.002). The dual-luciferase activity assay confirmed that hsa_circ_0000672 exerted biological functions as a sponge of miR-516a-5p to regulate expression of its target gene TRAF6. Hsa_circ_0000672 expression in peripheral blood monocytes may be associated with atrial fibrosis. The hsa_circ_0000672 may be involved in atrial fibrosis by indirectly regulating TRAF6 as a ceRNA by sponging miR-516a-5p.

Safety and Efficacy of High Power Shorter Duration Ablation Guided by Ablation Index or Lesion Size Index in Atrial Fibrillation Ablation: A Systematic Review and Meta-Analysis.

BACKGROUND: High power shorter duration (HPSD) ablation may lead to safe and rapid lesion formation. However, the optimal radio frequency power to achieve the desired ablation index (AI) or lesion size index (LSI) is insubstantial. This analysis aimed to appraise the clinical safety and efficacy of HPSD guided by AI or LSI (HPSD-AI or LSI) in patients with atrial fibrillation (AF). METHODS: The Medline, PubMed, Embase, Web of Science, and the Cochrane Library databases from inception to November 2020 were searched for studies comparing HPSD-AI or LSI and low power longer duration (LPLD) ablation. RESULTS: Seven trials with 1013 patients were included in the analysis. The analyses verified that HPSD-AI or LSI revealed benefits of first-pass pulmonary vein isolation (PVI) (RR: 1.28; 95% CI: 1.05-1.56, P = 0.01) and acute pulmonary vein reconnection (PVR) (RR: 0.65; 95% CI: 0.48-0.88, P = 0.005) compared with LPLD. HPSD-AI or LSI showed higher freedom from atrial tachyarrhythmia (AT) (RR = 1.32, 95% CI: 1.14-1.53, P = 0.0002) in the subgroup analysis of studies with PVI ± (with or without additional ablation beyond PVI). HPSD-AI or LSI could short procedural time (WMD: -22.81; 95% CI, -35.03 to -10.60, P = 0.0003), ablation time (WMD: -10.80; 95% CI: -13.14 to -8.46, P < .00001), and fluoroscopy time (WMD: -7.71; 95% CI: -13.71 to -1.71, P = 0.01). Major complications and esophageal lesion in HPSD-AI or LSI group were no more than LDLP group (RR: 0.58; 95% CI: 0.20-1.69, P = 0.32) and (RR: 0.84; 95% CI: 0.43-1.61, P = 0.59). CONCLUSIONS: HPSD-AI or LSI was efficient for treating AF with shorting procedural, ablation, and fluoroscopy time, higher first-pass PVI, and reducing acute PVR and may increase freedom from AT for patients with additional ablation beyond PVI compared with LPLD. Moreover, complications and esophageal lesion were low and no different between two groups.

[Effects of pretreatment with metoprolol on cardiomyocyte apoptosis and caspase-8 activation after coronary microembolization in rats].

OBJECTIVE: To investigate the effects of metoprolol on cardiomyocyte apoptosis and caspase-8 activation after coronary microembolization(CME) in rats. METHODS: Adult rats were randomly assigned into CME group (intraventricular injection of 3000 microspheres with 42 µm in diameter), sham-operated group (0.1 ml saline) and CME plus metoprolol group (pretreatment with 3 bolus metoprolol 2.5 mg/kg intravenous injection at 10 minutes interval at 30 minutes before microspheres injection, n = 15, each group). Cardiac function was evaluated by echocardiography at 6 hours post various treatments. Cardiomyocyte apoptosis was detected with TUNEL staining and the expression of caspase-3 and caspase-8 was detected with Western blot analysis. RESULTS: Compared with sham-operated group, LVEF (72.68% ± 3.26% vs. 82.64% ± 3.43%, P < 0.05), fractional shortening (FS) (37.46% ± 2.38% vs. 42.85% ± 3.25%) and cardiac output (CO) [(0.101 ± 0.006) L/min vs. (0.162 ± 0.008) L/min] were significantly reduced while left ventricular end-diastolic diameter (LVEDd) [(6.22 ± 0.17) mm vs. (5.18 ± 0.43) mm] was significantly increased in CME group (all P < 0.05). Cardiac function [LVEF:73.94% ± 4.22%, FS:38.53% ± 2.03%, CO:(0.120 ± 0.012) L/min, LVEDd:(6.18 ± 0.27) mm] was similar in CME plus metoprolol group compared to CME group (all P > 0.05). The cardiomyocytes apoptosis rates (3.19% ± 1.23% vs. 0.18% ± 0.10%) and the levels of activated caspase-3 and caspase-8 proteins were significantly increased in CME group than in sham-operated group (all P < 0.05). The cardiomyocyte apoptosis rate (1.32% ± 0.28%) and the levels of activated caspase-3 and caspase-8 proteins were significantly lower in CME plus metoprolol group than in CME group (all P < 0.05). CONCLUSIONS: Metoprolol pretreatment reduced post-CME myocardial apoptosis possibly through downregulating death receptor-mediated apoptotic pathway.

Effect of metoprolol on myocardial apoptosis and caspase-9 activation after coronary microembolization in rats.

OBJECTIVE: To explore the effect of metoprolol on myocardial apoptosis and caspase-9 activation after coronary microembolization (CME) in rats. METHODS: Forty rats were randomly divided into four groups (n=10 each): a sham operation (control) group, CME plus saline (CME) group, CME plus metoprolol (metoprolol) group and caspase-9 inhibitor Z-LEHD-FMK (ZLF) group. CME was induced by injecting 3000 polyethylene microspheres (42 µm diameter) into the left ventricle during a 10 s occlusion of the ascending aorta. Echocardiography, terminal deoxynucleotidyl transferase dUTP nick end labelling and Western blotting were used to evaluate cardiac function, apoptosis and activation of caspase-9/caspase-3, respectively, 6 h after CME. RESULTS: The echocardiographic parameters of left ventricular function were significantly decreased in the CME group compared with the control group (P<0.05); however, the metoprolol group and ZLF group showed significantly improved cardiac function compared with CME alone (P<0.05). Compared with the control group, the myocardial apoptosis rate and the levels of activated caspase-9 and -3 increased significantly in the CME group (P<0.05). Again, these effects were ameliorated by metoprolol and ZLF (P<0.05). CONCLUSIONS: The present study demonstrates that metoprolol and ZLF can protect the rat myocardium during CME by inhibiting apoptosis and improving cardiac function, likely by inhibiting apoptosis/ mitochondrial apoptotic pathway. These results suggest that antiapoptotic therapies may be useful in treating CME.

Effect of metoprolol on myocardial apoptosis after coronary microembolization in rats.

BACKGROUND: Coronary microembolization (CME) is a serious complication following percutaneous coronary intervention (PCI) in patients with acute coronary syndromes. The use of metoprolol before PCI can significantly protect ischemic myocardium from myocardial damage, but the function of metoprolol in the treatment of CME is not entirely clear. This study was to explore the effect and significance of metoprolol on myocardial apoptosis and caspase-3 activation after CME in rats. METHODS: Thirty rats were randomly divided into three groups including sham-operation (control group), CME plus saline (CME group), CME plus metoprolol (metoprolol group), 10 rats for each group. The CME group was induced by injecting 3 000 polyethylene microspheres (42 µm) into the left ventricle during a 10-second occlusion of the ascending aorta; the control group was injected with physiological saline instead of microembolization ball; the metoprolol or saline group was given three intravenous bolus injections before CME. Echocardiography, TUNEL staining, and Western blotting were used to evaluate cardiac function, proportion of apoptotic cells and activation of caspase-3 respectively at 6 hours after operation. RESULTS: Echocardiographic parameters displayed that the metoprolol group improved cardiac function significantly compared with the CME group (P<0.05). The myocardial apoptotic rate of the CME group as well as the contents of activated caspase-3 increased significantly (P<0.05), both of which were ameliorated significantly by metoprolol treatment (P<0.05). CONCLUSIONS: This study demonstrates that metoprolol can protect the myocardium during CME in rats by inhibiting apoptosis and improving cardiac function. These results suggest that the inhibition of apoptosis can be a potential therapeutic strategy for the treatment of CME.

Coronary microembolization induced myocardial contractile dysfunction and tumor necrosis factor-α mRNA expression partly inhibited by SB203580 through a p38 mitogen-activated protein kinase pathway.

BACKGROUND: The microemboli produced during spontaneous plaque rupture and ulceration and during coronary intervention will reduce coronary reserve and cause cardiac dysfunction. It is though that inflammation caused by the microinfarction induced by the microembolization may play an essential role. It is known that the activation of p38 mitogen-activated protein kinases (MAPK) in both infected and non-infected inflammation in myocardium may cause a contractile dysfunction. But the relation between the activation of p38 MAPK and microembolization is still unknown. METHODS: Sprague-Dawley rats were randomly divided into three groups: Sham group, coronary microembolization (CME) group and SB203580 group (n = 10 per group). CME rats were produced by injection of 42 µm microspheres into the left ventricle with occlusion of the ascending aorta. SB203580, a p38 MAPK inhibitor, was injected into the femoral vein after the injection of microspheres to make the SB203580 group. Left ventricular ejection fraction (LVEF) was determined by echocardiography. The protein concentration of P38 MAPK in the myocardium was assessed by Western blotting. The relative expression of mRNA for tumor necrosis factor (TNF)-α was assessed by the technique of semi-quantitative polymerase chain reaction amplification. RESULTS: LVEF was depressed at three hours up to 12 hours in the CME group. Increased p38 MAPK activity and TNF-α mRNA expression were observed in the CME group. The administration of SB203580 partly inhibited p38 MAPK activity, but did not fully depress the TNF-α expression, and partly preserved cardiac contractile function. CONCLUSIONS: p38 MAPK is significantly activated by CME and the inhibition of p38 MAPK can partly depress the TNF-α expression and preserve cardiac contractile function.

Beta blocker metoprolol protects against contractile dysfunction in rats after coronary microembolization by regulating expression of myocardial inflammatory cytokines.

AIMS: To examine the effects of metoprolol on expression of myocardial inflammatory cytokines and myocardial function in rats following coronary microembolization (CME). MAIN METHODS: Male rats were randomly assigned to receive either sham-operation (control group), CME plus saline (CME group), or CME plus metoprolol (metoprolol group). CME was induced by injecting 3000 polyethylene microspheres (42 µm) into the left ventricle during a 10-second occlusion of the ascending aorta. Metoprolol (2.5mg/kg) or saline was administered as three intravenous bolus injections after CME. At 3h, 6h, 12h, 24h and 4 weeks after CME, myocardial function was measured with echocardiography; and the mRNA and protein levels of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) and interleukin 1-ß (IL-1ß) were determined. KEY FINDINGS: Induced CME led to markedly higher mRNA and protein levels of TNF-α, IL-1ß and IL-10 at 3, 6, 12, and 24h, as well as reduced left ventricular function, compared to the control group. Metoprolol administration reduced TNF-α and IL-1ß levels, but increased IL-10 levels at 3, 6, 12, and 24h compared to the CME group. Moreover, metoprolol treatment resulted in significantly improved left ventricular function at 12h, 24h and 4 weeks, but afforded no cardiac protection at 3h and 12h, compared to the CME group. SIGNIFICANCE: Higher levels of TNF-α and IL-1ß in rats following CME are associated with the development of myocardial contractile dysfunction. Metoprolol-conferred protection against progressive contractile dysfunction following CME may be mediated by its anti-inflammation potential.

The role of ERK1/2 signaling pathway in coronary microembolization-induced rat myocardial inflammation and injury.

AIM: Inflammation plays an important role in coronary microembolization (CME)-induced myocardial injury. The present study was designed to investigate the role of extracellular signal-regulated kinases 1/2 (ERK1/2) signaling pathway in regulating myocardial inflammation and cardiac function in a rat model of CME. METHODS: Sprague-Dawley rats were randomly divided into three groups: sham-operated group (sham group), CME group and PD98059 group (15 animals per group). CME was produced by injection of 42-µm microspheres into the left ventricle with occlusion of the ascending aorta. Rats in the PD98059 group were injected with PD98059, a specific ERK1/2 inhibitor, 30 min before the CME operation. Western blotting and immunohistochemistry analysis were used to determine the activation of ERK1/2. Echocardiography was employed to evaluate cardiac function. Hematoxylin-eosin staining was performed to assay myocardial inflammation. Expression of TNF-α mRNA was determined by RT-PCR analysis, and activity of NF-κB was assessed by electrophoretic mobility shift assay. RESULTS: CME dramatically induced cardiac dysfunction (left ventricular ejection fraction, LVEF, was 72.97 ± 3.20% in the CME vs. 82.69 ± 3.50% in the sham group, p < 0.05) and local myocardial inflammatory response, both of which were ameliorated significantly by PD98059 (LVEF was 76.46 ± 4.46 and p < 0.05 vs. CME group). When compared to the CME group, PD98059 markedly attenuated the increased phosphorylation of ERK1/2 (0.48 ± 0.11 vs. 0.92 ± 0.10, p < 0.05), expression of TNF-α mRNA (0.42 ± 0.06 vs. 0.94 ± 0.04, p < 0.05) and activity of NF-κB (104.83 ± 13.65 vs. 540.79 ± 24.95, p < 0.05) in CME rat myocardium. CONCLUSIONS: The present study demonstrates a novel role of the ERK1/2 signaling pathway in promoting myocardium inflammation and dysfunction in CME, and suggests that ERK1/2 is a novel potential therapeutic target for CME.

Altered expression of pro- and anti-inflammatory cytokines is associated with reduced cardiac function in rats following coronary microembolization.

Coronary microembolization (CME) is a spontaneous event in patients with ischemic heart disease and a potential iatrogenic complication in patients undergoing coronary interventions. CME induces an obvious inflammatory reaction, characterized by cellular infiltration, particularly of eosinophils, and multifocal microinfarcts. However, little is known on the correlation between pro- and anti-inflammatory cytokines and cardiac function following CME. In this study, microspheres with a diameter of 42 mum were intracoronarily injected into the apex of the left ventricle to induce CME (CME group). Rats injected with normal saline served as controls (sham operated control group). Expression of pro-inflammatory cytokines, TNF-alpha and IL-1beta, and an anti-inflammatory cytokine, IL-10, was measured at 3, 6, 12, 24 h, and 4 weeks post-injection by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. At the same time points, cardiac function and histological changes were evaluated by echocardiographic imagining and H&E staining, respectively. It was observed that the mRNA and protein expressions of TNF-alpha, IL-1beta, and IL-10 all started to increase at 3 h, reached to the peak levels at 12 h, and returned to the normal levels at 4 weeks post-injection. The left ventricular ejection fraction (LVEF) was significantly lower in the CME group than in the control group at 3, 6, 12, 24 h, and 4 weeks post-injection. Obvious myocardial microinfarcts with surrounding myocardial edema and degeneration, caryolysis, and infiltration of neutrophils and monocytes were observed in the CME group at 3, 6, 12, 24 h, and 4 weeks post-injection. Moreover, mRNA expression of TNF-alpha and IL-1beta was negatively correlated with LVEF, although not with myocardial microinfarcts, in the CME group. It is concluded that both protein and mRNA expression of TNF-alpha IL-1beta and IL-10 are dynamically changed following CME, which is associated with reduced cardiac function. Therefore, these cytokines may be potential therapeutic targets for clinical treatment of CME.

[Myocardial inflammation and injury induced by coronary microembolization in rats: role of ERK1/2 signaling pathway].

OBJECTIVE: To determine the role of extracellular signal-regulated kinases1/2 (ERK1/2) signaling pathway in regulating myocardial inflammation and cardiac function in a rat model of coronary microembolization (CME). METHODS: The Sprague-Dawley rats were randomly divided into three groups: sham-operated group (n = 15), coronary microembolization group (n = 15) and PD98059 group (n = 15). CME model was established by injection of 42 microm microspheres 0.1 ml (3 x 10(4)/ml, 3000)into left ventricle while occluding the ascending aorta. At 30 minutes pre-operation, rats of PD98059 group were injected with PD98059 IV, a specific ERK1/2 inhibitor. Western blot and immunochemical analysis were used to determine the activation and distribution of ERK1/2. Echocardiography was employed to evaluate cardiac functions. The hematoxylin-eosin staining was used to assay myocardial inflammation. Expression of TNF-alpha and MIF mRNA was determined by RT-PCR analysis and activity of NF-kappaB assessed by electrophoretic mobility shift assay. RESULTS: In comparison with sham-operated group, CME increased phosphorylation of ERK1/2 (0.92 +/- 0.10 vs 0.61 +/- 0.04), local myocardial inflammatory cells (455 +/- 16 vs 47 +/- 7), expression of TNF-alpha mRNA (0.94 +/- 0.04 vs 0.60 +/- 0.09) and MIF mRNA(1.30 +/- 0.44 vs 0.63 +/- 0.25) and activity of NF-kappaB (541 +/- 25 vs 311 +/- 65) in myocardium(all P < 0.05). All of these dramatically induced cardiac dysfunction [LVEF (73 +/- 3)% vs (83 +/- 4)%, P < 0.05]. To compare with CME group, treatment of specific ERK1/2 inhibitor PD98059 blocked the activation of ERK1/2 (0.48 +/- 0.11 vs 0.92 +/- 0.10, P < 0.05), decreased inflammatory cells (401 +/- 12 vs 455 +/- 16, P < 0.05), decreased expression of TNF-alpha mRNA (0.42 +/- 0.06 vs 0.94 +/- 0.04, P < 0.05) and suppressed activity of NF-kappaB (105 +/- 14 vs 541 +/- 25, P < 0.05). Most importantly, PD98059 treatment ameliorated cardiac functions dramatically [LVEF (76 +/- 4)% vs (73 +/- 3)%, P < 0.05]. However there was no significant change in the expression of MIF mRNA (1.17 +/- 0.37 vs 1.30 +/- 0.44, P > 0.05). CONCLUSION: The present study demonstrates a novel role of ERK1/2 signaling pathway in promoting myocardial inflammation in CME. And ERK1/2 may be a novel drug target for CME therapy.