Impact of heart rate reduction on recurrence after catheter ablation of persistent atrial fibrillation

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Johnson & Johnson KK

OnBehalf

OCVC Arrhythmia Investigators

Background

Predicting heart rate (HR) after restoration of sinus rhythm (SR) remains one of the challenges when performing catheter ablation (CA) of persistent atrial fibrillation (AF).

Purpose

To evaluate the association between pre-ablation HR during AF and post-ablation HR during SR, and whether the HR reduction is associated with AF recurrence.

Methods

The analysis was performed from the EARNEST-PVI trial, a randomized controlled trial designed to assess a CA strategy for persistent AF, which was conducted in the Osaka region of Japan. After excluding patients with beta-blocker prescription, a total of 216 patients (median age, 67 years; 20% female; 23% long-standing persistent AF) with AF rhythm at baseline and SR at discharge were enrolled in this study. Baseline HR during AF and post-ablation HR during SR was measured on admission and at discharge using the 12-lead electrocardiograms, respectively.

Results

There was a mild correlation between baseline HR (median 82 [interquartile range 72-95] bpm) and post-ablation HR (78 [48-117] bpm) (r = 0.27, p <0.001). Reduction in HR was positively associated with baseline HR (r = 0.79, p <0.001) and was negatively associated with post-ablation HR (r = - 0.37, p <0.001). During the follow-up of 1 year, 56 patients (25.9%) experienced AF recurrence. HR reduction had the higher diagnostic accuracy in predicting AF recurrence than HR at baseline and HR after CA (area under the curve, 0.625; 95% confidence interval, 0.557–0.690; p = 0.003). AF recurrence rate was significantly higher in 141 patients with smaller HR reduction (cut-off, <14bpm) than those with larger HR reduction (31.9% vs. 14.7%, p = 0.009). After adjustment of age, gender, long-standing persistent AF, and CA strategy, HR reduction of <14 bpm was a significant predictor of AF recurrence (hazard ratio, 2.32; 95% confidence interval, 1.20–4.51; p = 0.013).

Conclusions

There was a mild correlation between HR during AF and HR after restoration of SR in patients underwent CA of persistent AF. HR reduction after restoration of SR predicted AF recurrence.

Reappraising the role of baseline plasma C-reactive protein levels on recurrence after catheter ablation of persistent atrial fibrillation: insight from EARNEST-PVI trial

Background

Subclinical inflammation is an important pathogenesis of developing and sustaining atrial fibrillation (AF). Because AF itself contribute to the inflammatory response, the role of baseline subclinical inflammation on AF recurrence after catheter ablation (CA) remains controversial in patients with persistent AF.

Purpose

To evaluate whether baseline plasma C-reactive protein (CRP) levels, a sensitive marker of inflammation, are associated with AF recurrence following CA.

Methods

The analysis was performed from the EARNEST-PVI trial, a randomized controlled trial designed to assess a CA strategy for persistent AF, which was conducted in the Osaka region of Japan. A total of 441 patients (median age, 67 years; 26% female; 25% long-standing persistent AF) whose plasma CRP levels were measured at baseline were included in this study.

Results

At baseline, a median (interquartile range) of plasma CRP level was 0.10 [0.06–0.19] mg/dl. Plasma CRP levels significantly increased at discharge (0.83 [0.21–1.84] mg/dl, p<0.001) and decreased 1 year after CA (0.10 [0.05–0.20] mg/dl, p=0.040) compared to the baseline value. During the follow-up of 1 year, 115 patients (26%) experienced AF recurrence, and the incidence was significantly higher in 124 patients with low CRP levels at baseline (cut-off ≤0.06 mg/dl) than the other 317 patients (33.9% vs. 23.0%, p=0.017). After adjustment of age, gender, body mass index, long-standing persistent AF, CA strategy, and plasma brain natriuretic peptide levels, low plasma CRP levels was a significant predictor of AF recurrence (hazard ratio, 1.51; 95% confidence interval, 1.02–2.24; p=0.042).

Conclusions

Low plasma CRP levels at baseline predicted AF recurrence in the EARNEST-PVI trial. Reappraising the role of CRP on AF recurrence may be needed in patients with persistent AF.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Johnson & Johnson KK

Renal function and arrhythmia outcomes in persistent atrial fibrillation patients after catheter ablation: subanalysis of the EARNEST-PVI trial

Background

Atrial fibrillation (AF) reduces the renal function. Renal dysfunction and AF often coexist. Catheter ablation (CA) of persistent AF can maintain a sinus rhythm and may improve the renal function.

Purpose

We sought to elucidate whether the estimated glomerular filtration rate (eGFR) in patients with persistent AF was increased after CA, especially with the presence of an AF recurrence.

Methods

We enrolled 487 persistent AF patients whose eGFR data were available both before and 1-year after the CA out of 512 patients in the EARNEST-PVI trial.

Results

The mean age was 65±9 year and 113 patients (24.8%) had long-standing persistent AF. We compared the eGFR at baseline with that 1-year after the CA. AF recurrences were recognized in 118 patients (25.8%). The eGFR was similar between the group without recurrence and that with recurrence at baseline (without AF recurrence vs. with AF recurrence; 63.8±14.3 vs. 62.7±13.6 mL/min/1.73m2, p=0.46). In patients without AF recurrence, the G1, G2, G3a, G3b, G4, and G5 were 13 (3.8%), 198 (58.4%), 98 (28.9%), 26 (7.7%), 3 (0.9%), and 1 (0.3%), respectively at baseline. In the patients with AF recurrence, the G1, G2, G3a, G3b, G4, and G5 were 3 (2.5%), 68 (57.8%), 38 (32.2%), 6 (5.1%), 3 (2.5%), and 0 (0%), respectively at baseline. The ΔeGFR was significantly higher in the patients without AF recurrence than in those with AF recurrence (without AF recurrence vs. with AF recurrence; 5.1 [−0.3, 10.8] vs. 3.0 [−3.0, 7.6], p=0.0033). In the patients without AF recurrence, a better eGFR class at 1-year after the CA than in those before the CA was recognized in 75 patients (22.1%), while it was recognized in 19 patients (16.1%) with AF recurrences.

Conclusion

Successful catheter ablation in patients with persistent AF led to a better renal outcome.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This study was funded by Medtronic, Johnson & Johnson, and Abbott.

Differences in quality of life improvement with pulmonary vein isolation alone vs. more extensive ablation of persistent atrial fibrillation: insights from the EARNEST-PVI trial

Background

Improving the quality of life (QoL) is one of the main purposes of catheter ablation (CA) of persistent atrial fibrillation (AF). QoL improvement in persistent AF patients has not been fully clarified. The EARNEST-PVI trial was a multi-center randomized trial comparing clinical outcomes of pulmonary vein isolation (PVI) alone and more intensive ablation in addition to PVI including complex fractionated atrial electrogram (CFAE) and linear ablation (PVI plus).

Purpose

To investigate the QoL change after persistent AF ablation and the differences between the PVI-alone strategy and the PVI plus strategy.

Methods

In the EARNEST-PVI trial, patients with persistent AF who underwent an initial catheter ablation (n=512) were randomly assigned in a 1:1 ratio to either PVI alone or PVI plus. Quality of life was assessed at baseline and at 12 months after ablation for AF using the 36-Item Short Form Health Survey. Scores were also converted to a physical health component summary (PCS), a mental health component summary (MCS) and a role/social component summary (RCS).

Results

In the EARNEST-PVI trial, the PVI alone strategy was associated with higher recurrence rate compared with the PVI plus additional ablation strategy. After excluding 68 patients for whom preoperative or postoperative QoL assessment was not available, 222 patients were evaluated respectively. Overall, significant improvements in PCS (46.2±11.4 to 48.7±11.4]), MCS (50.1±8.8 to 54.3±8.6) and RCS (44.6±13.3 to 48.6±11.3) occurred 12 months after ablation (P<0.001, respectively). Although significant QoL improvement occurred in both PVI alone and PLI plus strategies, the changes in PCS was greater in the PVI-plus than that in PVI-alone (3.5±10.3 vs 1.5±10.6, P=0.04).

Conclusions

Ablation for persistent atrial fibrillation improved both physical and mental quality of life. The PVI-plus strategy showed greater improvement in physical QoL.

Funding Acknowledgement

Type of funding sources: None. QoL improvement

Rab10-Positive Tubular Structures Represent a Novel Endocytic Pathway That Diverges From Canonical Macropinocytosis in RAW264 Macrophages

Using the optogenetic photo-manipulation of photoactivatable (PA)-Rac1, remarkable cell surface ruffling and the formation of a macropinocytic cup (premacropinosome) could be induced in the region of RAW264 macrophages irradiated with blue light due to the activation of PA-Rac1. However, the completion of macropinosome formation did not occur until Rac1 was deactivated by the removal of the light stimulus. Following PA-Rac1 deactivation, some premacropinosomes closed into intracellular macropinosomes, whereas many others transformed into long Rab10-positive tubules without forming typical macropinosomes. These Rab10-positive tubules moved centripetally towards the perinuclear Golgi region along microtubules. Surprisingly, these Rab10-positive tubules did not contain any endosome/lysosome compartment markers, such as Rab5, Rab7, or LAMP1, suggesting that the Rab10-positive tubules were not part of the degradation pathway for lysosomes. These Rab10-positive tubules were distinct from recycling endosomal compartments, which are labeled with Rab4, Rab11, or SNX1. These findings suggested that these Rab10-positive tubules may be a part of non-degradative endocytic pathway that has never been known. The formation of Rab10-positive tubules from premacropinosomes was also observed in control and phorbol myristate acetate (PMA)-stimulated macrophages, although their frequencies were low. Interestingly, the formation of Rab10-positive premacropinosomes and tubules was not inhibited by phosphoinositide 3-kinase (PI3K) inhibitors, while the classical macropinosome formation requires PI3K activity. Thus, this study provides evidence to support the existence of Rab10-positive tubules as a novel endocytic pathway that diverges from canonical macropinocytosis.

A novel DENND1B-localized structure found at the basal side of adherent cells

Rab35 is a small G protein involved in various cellular events including clathrin-dependent endocytosis, phagocytosis, and autophagy. DENND1B, a DENN family member, acts as a guanine nucleotide exchange factor (GEF) for Rab35 to convert it to the GTP-bound active form from the GDP-bound inactive form. DENND1B contains the DENN domain which harbors GEF activity for Rab35 in the N-terminus, while the clathrin binding motif and adaptor protein-2-interaction motif are at the C-terminus. In this study, we investigated the intracellular localization of DENN1B in various cell types and found novel DENND1B-localized gathered line structures in BS-C-1 cells and in some other cell types. The localization of DENND1B to gathered line structures was dependent on a specific region located in the C-terminus of DENND1B protein. DENND1B-localized gathered lines were partially associated with microtubules but not with F-actin; instead, F-actin bundles surrounded the assembly of gathered lines. We also show that the gathered line structures appeared at the bottom of spreading lamellipodia and disappeared at the retracting site during cell motility in EGF-stimulated BS-C-1 cells. These results shed light on a new role for DENND1B in the regulation of cell migration.

Negative impact of ultra-thin strut on neointimal coverage condition within one year after implantation as compared to thin sturt in biogradable-polymer sirorimus eluting stents

Background

BIOSCIENCE randomized trial which compared biodegradable-polymer sirolimus-eluting stents with ultra-thin (60μm) strut (ultra-thin BP-SES) and durable-polymer everolimus-eluting stents with thin (81μm) strut (thin DP-EES) have reported that definite stent thrombosis within 1 year had more frequently occurred in ultra-thin BP-SES (0.9%) than in thin DP-EES group (0.4%) although it was not statistically significant. It suggests that neointimal coverage after stent implantation within 1 year might be different between ultra-thin BP-SES and thin DP-EES. Recently, two types of biogradable-polymer sirorimus eluting stents, thin (80μm) strut type (thin BP-SES) and ultra-thin (60μm) strut type (ultra-thin BP-SES), can be available in clinical settings.

Purpose

We compared neointimal coverage conditions between ultra-thin BP-SES and thin BP-SES by optical coherence tomography (OCT).

Methods

Consecutive Forty-six patients who underwent 21 ultra-thin BP-SESs or 25 thin BP-SESs implantation were enrolled. We compared incidences of acute coronary syndrome, type B2/C lesion, atherectomy device use, stent size, stent length, maximum inflation pressure, and 8-month follow-up OCT parameters including proportions of uncovered struts (%Uncovered), malapposed struts, (%Mallaposed) and mean neointimal hyperplasia thickness (mean NHT) between the two groups.

Results

%Uncovered and %malapposed were significantly higher and mean NHT was significantly lower in ultra-thin BP-SES than in thin BP-SES (Table). The other parameters were similar between the two groups.

Conclusion

Ultra-thin BP-SES showed worse neointimal coverage as compared to thin BP-SES within 1 year after stent implantation, which may increase stent thrombosis.

Funding Acknowledgement

Type of funding source: None

Real-world clinical impact of external elastic lamina-based stent sizing criteria using optical coherence tomography

Introduction

ILUMIEN III trial has reported that non-inferiority of optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) to intravascular ultrasound-guided PCI for postprocedural minimum stent area. In the trial, external elastic lamina (EEL)-based stent sizing criteria was introduced, however OCT has limitations including incomplete visualization of EEL in severale lesions.

Purpose

The aim of the study is to investigate real-world clinical impact of EEL-based stent sizing criteria.

Methods

The study included consecutive patients who underwent OCT-guided percutaneous coronary intervention (PCI) for de novo lesions in our institution between September 2016 and April 2018. EEL visibility, mean EEL diameter, mean lumen diameter and plaque morphology were assessed at proximal and distal references. The plaque morphology at references was categorized according to its most prevalent component as follows: normal, fibrous plaque, lipid plaque, and calcified plaque. Both references were divided into 3 groups according to visibility of EEL.

Results

Among 205 lesions, 31 lesions had artifacts at references (16 proximal and 17 distal references). EEL visibility was summarized in a table. Out of 174 lesions with both analyzable references, 111 lesions (63.8%) had >180-degree EEL visibility at both references. Proportion of plaque morphology were significantly different among 3 groups at proximal and distal references as shown in a figure.

Conclusions

EEL-based stent sizing criteria was usable for 63.8% of all the lesions. Vessel size and plaque morphology were significantly associated with EEL visibility.

Proportion of plaque morphology

Funding Acknowledgement

Type of funding source: None

Difference of myocardial injury, inflammation and early recurrence after pulmonary vein isolation among laser balloon ablation, radiofrequency catheter ablation and cryoballoon ablation

Background

Pulmonary vein isolation (PVI) has become well-established as the main therapy for patients with drug-refractory paroxysmal atrial fibrillation (PAF) and various isolation methods including radiofrequency ablation (RFA), cryoballoon ablation (CBA) and laser balloon ablation (LBA) were available. Pathological findings in each ablation methods such as myocardial injury and inflammation are thought to be different. High sensitive cardiac troponin I (hs-TnI), subunit of cardiac troponin complex, is a sensitive and specific marker of myocardium injury. High-sensitive C-reactive protein (hs-CRP) is a biomarker of inflammation and is elevated following cardiomyocyte necrosis. Relationship between myocardial injury and inflammation after ablation using RFA, CBA and LBA and early recurrence of atrial fibrillation (ERAF) remains unclear.

Methods

We enrolled consecutive PAF patients from Osaka Rosai Atrial Fibrillation (ORAF) registry who underwent PVI from January 2019 to October 2019. We compared the clinical characteristics including age, gender, hypertension, diabetes mellitus, history of heart failure, CHADS2Vasc score, renal function, serum BNP level and echocardiographic parameters including left ventricular dimensions, left atrial diameter (LAD) and left ventricular ejection fraction (LVEF) between RFA, CBA and LBA groups. We investigated the difference of relationship between myocardial injury marker (hs-TnI), inflammation markers (white blood cell change (DWBC) from post to pre PVI, neutrophil-to-lymphocyte ratio change (DNLR) from after to before PVI and hs-CRP) at 36–48 hours after PVI and ERAF (<3 months after PVI) between each group.

Results

We enrolled 187 consecutive PAF patients who underwent PVI. RFA, CBA and LBA groups comprised 108, 57 and 22 patients, respectively. There were no significant differences of age, gender, hypertension, diabetes mellitus, history of heart failure, CHADS2Vasc score, renal function, serum BNP level and echocardiographic parameters between each group. Serum hs-TnI in RFA group and LBA group were significantly lower than in CBA group (2.643 ng/ml vs 5.240ng/ml, 1.344 ng/ml vs 5.240 ng/ml, p<0.001, p=0.002, respectively, Figure). DWBC was significantly higher in LBA group than CBA group (1157.3/μl vs 418.4/μl, p=0.045). DNLR did not differ between each group. Hs-CRP in RFA group and LBA group were significantly higher than in CBA group (1.881 mg/dl vs 1.186 mg/dl, 2.173 mg/dl vs 1.186 mg/dl, p=0.010, p=0.003, respectively, Figure). Incidence of ERAF was significantly higher in LBA group than RFA group (36.4% vs 16.7%, p=0.035). Incidence of ERAF tended to be higher in LBA group than CBA group (36.4% vs 19.3%, p=0.112).

Conclusion

LBA may cause less myocardial injury than RFA and CBA, on the contrary LBA may cause more inflammation than CBA. Incidence of ERAF in LBA was highest between each procedure.

Inflammation markers and ERAF

Funding Acknowledgement

Type of funding source: None

Outcome of contact force-guided radiofrequency catheter ablation or second generation cryoballoon ablation for paroxysmal atrial fibrillation: propensity score matched analysis

Background

Little has been reported on the outcome of contact force (CF)-guided radiofrequency catheter ablation (RFCA) and second generation cryoballoon ablation (CBA).

Purpose

The purpose of this study was to compare the outcome of CF-guided RFCA and second generation CBA for paroxysmal atrial fibrillation (PAF).

Methods

We enrolled the consecutive 364 patients with PAF who underwent initial ablation between September 2014 and July 2018 in our hospital. We compared the late recurrence of atrial tachyarrhythmia more than three months after ablation between RFCA group and CBA group. All RFCA procedures were performed using CF-sensing catheter and all CBA procedures were performed using second generation CB.

Results

There were significant differences in background characteristics: chronic kidney disease, serum brain natriuretic peptide level, and left ventricular ejection fraction. After propensity score matched analysis (Table), atrial tachyarrhythmia free survival was significantly higher in CBA group than in RFCA group (Figure).

Conclusions

Second generation CBA showed a significantly lower late recurrence rate compared to CF-guided RFCA.

Kaplan-Meier Curve

Funding Acknowledgement

Type of funding source: None

Not only power and energy but also balloon size is correlated with lesion formation in laser ablation model in vitro study

Background

Power and total energy were known to correlate with lesion formation during laser balloon ablation for atrial fibrillation. However, it is unclear whether balloon size can influence lesion formation. The aim of this study was to evaluate the impact of balloon size on lesion formation during laser balloon procedure in vitro model.

Methods

Laser energy was applied to chicken muscles using first generation laser balloon. Laser ablation was performed with different 2 balloon size (18mm and 32mm) using 2 different power settings (12W/20sec and 8.5W/20sec). Forty lesions were evaluated for each setting. We compared maximum lesion width, maximum lesion depth, depth at maximum width and endocardial lesion width between 18mm and 32mm balloon groups at 12W/20sec and 8.5W/20sec, respectively.

Results

At 8.5W/20sec, inadequate lesion formation to assess lesion size was observed in 1/40 lesion of 18mm balloon group and in 5/40 lesions of 32mm balloon group. Thus, at 8.5W/20sec 18 mm balloon group consisted of 39 lesions and 32 mm balloon group consisted of 35 lesions. At 12W/20sec 18 mm balloon group consisted of 40 lesions and 32 mm balloon group consisted of 40 lesions. At both power settings, maximum lesion depth was larger in 18mm balloon than in 32mm balloon group. At 12W/20sec setting, maximum lesion width and endocardial width were larger in 32mm balloon group than in 18mm balloon group. At 12W/20sec setting, depth at maximum width was smaller in 32mm balloon group than in 18mm balloon group. Lesion morphologies were summarized in a figure.

Conclusion

Balloon size could affect lesion formation during laser balloon ablation in addition to laser power and energy. Laser ablation lesion were wider but shallower in 32mm balloon group compared with in 18mm balloon group.

Funding Acknowledgement

Type of funding source: None

Clinical characteristics and outcomes after pulmonary vein isolation in atrial fibrillation patients with complete right bundle branch block

Background

Complete right bundle branch block (CRBBB) is one of the most frequent alterations of the electrocardiogram (ECG). Several studies have shown that CRBBB was a risk factor for cardiovascular diseases and the appearance of CRBBB in patients hospitalized for exacerbated heart failure (HF) was associated with a worse prognosis. Various alternations of ECG such as early repolarization pattern and intraventricular conduction disturbance were associated with high recurrence ratio of atrial fibrillation (AF) after pulmonary vein isolation (PVI). However clinical outcome after PVI in patients with CRBBB remains unclear.

Methods

We enrolled consecutive AF patients who underwent PVI from September 2014 to November 2018 rom Osaka Rosai Atrial Fibrillation (ORAF) registry. We excluded patients with other wide QRS (left bundle branch block, ventricular pacing and unclassified intraventricular conduction disturbance) and divided into 2 groups; CRBBB (QRS duration ≥120msec) group and no-CRBBB (QRS duration <120) group. We compared the clinical characteristics including age, gender, hypertension, diabetes mellitus, history of heart failure, history of stroke, CHADS2Vasc score, paroxysmal AF (PAF), renal function, plasma brain natriuretic peptide (BNP) level and echocardiographic parameters including left ventricular end-diastolic diameter (LVDd), left ventricular end-systolic diameter (LVDs), left atrial diameter (LAD) and left ventricular ejection fraction (LVEF) between the 2 groups. We also compared the incidence of late recurrence of AF/atrial tachycardia (AT) between the 2 groups. We investigated whether CRBBB was an independent predictor of late recurrence of AF/AT after PVI by multivariate Cox analysis.

Results

We enrolled 736 consecutive AF patients who underwent PVI. CRBBB patients comprised 55 patients (7.5%). There were no significant differences of age, gender, hypertension, diabetes mellitus, history of heart failure, history of stroke, CHADS2Vasc score, PAF, renal function, plasma BNP level and echocardiographic parameters (LVDd, LVDs, LVEF and LAD) between the 2 groups. Incidence of AF/AT recurrence after PVI was significantly higher in CRBBB group than no-CRBBB group (Figure). CRBBB was an independently and significantly associated with late recurrence of AF/AT after PVI by multivariate Cox analysis (hazard ratio: 1.923, 95% CI: 1.190–2.961, p=0.009) in addition to female (p<0.001), no-PAF (p=0.005) and left atrial diameter (p=0.042).

Conclusion

CRBBB may be a strong predictor of AF/AT late recurrence after PVI.

AF/Ar recurrence after PVI

Funding Acknowledgement

Type of funding source: None

Clinical outcome of non-use of touch-up focal ablation catheters strategy during cryoballoon atrial fibrillation ablation

Background

It has been reported that frequent use of touch-up focal ablation catheters was related to worse outcomes after cryoballoon (CB) atrial fibrillation (AF) ablation. It is unknown whether non-use of touch-up focal ablation catheters strategy affects the outcome of AF ablation. Therefore, this study aimed to assess whether non-use of touch-up focal ablation catheters strategy improve clinical outcome after AF ablation using CB.

Methods

A total of 151 consecutive patients who received CB ablation from February 2017 to August 2019 were enrolled. Non-use of a touch-up focal ablation catheters strategy was started from February 2018. Patients were divided into 2 groups according to the type of strategy. In the non-touch-up group, pulmonary veins were isolated without touch-up focal ablation catheters as much as possible and in conventional group, touch-up focal ablation catheters were used as required. The 1-year atrial tachyarrhythmia free survival without class 1 or 3 antiarrhythmic drugs after a 90-day blanking period was assessed between the 2 groups.

Results

The conventional group consisted of 76 patients and the non-touch-up group consisted of 75 patients. Baseline characteristics were comparable between 2 groups. Touch-up focal ablation catheters were used more in the conventional group (11 patients, 14%) than non-touch-up group (0 patients, 0%) (p<0.001). Pulmonary isolation was achieved in all patients of both groups. Atrial tachyarrhythmia recurrence occurred more frequently in the non-touch-up group (15/75 patients, 20%) than conventional group (7/76 patients, 9%) (p=0.045).

Conclusion

Non-use of a touch-up focal ablation catheters strategy may be related to worse outcome after CB AF ablation.

Funding Acknowledgement

Type of funding source: None

Ablation index guide pulmonary vein isolation can reduce early recurrence of atrial fibrillation: a propensity score-matched analysis

Background

Ablation index (AI) is a novel marker of ablation lesion quality for radiofrequency ablation (RFA). It has been reported that AI guided pulmonary vein isolation (PVI) reduced pulmonary vein reconnection and late recurrence of atrial fibrillation (AF). However, little is known about the impact of AI guided PVI on early recurrence of AF (ERAF).

Purpose

The aim of this study is to clarify whether AI guided PVI can reduce ERAF.

Methods

From September 2014 to August 2019, consecutive AF patients who underwent 1st session PVI were enrolled. We compared prevalence of ERAF between AI guided PVI group (AI group) and conventional contact force guided PVI group (CF group) using propensity score-matched analysis, which adjusted patient backgrounds (age, sex, and body mass index (BMI)), type of AF, the history of heart failure, hypertension, diabetes and stroke, laboratory findings including estimated glomerular filtration rate (eGFR) and b-type natriuretic peptide (BNP), and echocardiographic parameters including left ventricular ejection fraction (LVEF) and left atrial diameter.

Results

Total 711 patients were enrolled. AI group comprised 233 patients and CF group comprised 233 patients. Prevalence of ERAF were significantly lower in AI group than in CF group significantly (21.5% vs 36.1%, p=0.001, Table).

Conclusions

AI guided PVI can reduce ERAF as compared to conventional method.

Funding Acknowledgement

Type of funding source: None

Multicenter study of novel mapping technique to detect non-pulmonary vein triggers excluding the origin from left atrial posterior wall and superior vena cava

Background

It has been reported that elimination of non-pulmonary vein (PV) triggers after PV isolation is a good predictor of atrial tachyarrhythmia free survival. However, precise mapping of triggers outside from superior vena cava (SVC) or left atrial posterior wall (LAPW) are difficult. The aim of this study is to assess the efficacy of self-reference mapping technique to eliminate non-PV triggers originated from outside of primordial pulmonary vein area.

Methods

Total of 431 patients (446 procedures) underwent atrial fibrillation (AF) ablation in a hospital and in a medical center from January 2017 to March 2019. After isolation of PV, non-PV triggers were induced with isoproterenol and/or adenosine triphosphate. Reproducible non-PV triggers were targeted to ablate using following self-reference mapping technique: A trigger conducts centrifugally and the earliest site should be distinguished from other later activated sites. Using a PentaRay multipolar catheter, the operators annotated the earliest site of local activation and a reference tag was placed. The multipolar catheter was then moved to the reference tag and the process repeated. Ultimately, we identified clusters of early circumferential activation and ablated.

Results

A total of 32 non-PV triggers excluding the origin from LAPW and SVC were induced in 23 patients. Nineteen triggers (59%) were located in the right atrium and 13 triggers (41%) in the left atrium (Figure 1). All triggers were eliminated with ablation and AF was non-inducible in all patients at the end of the procedure. During the follow-up (529±270 days), 18 patients (77%) were free from atrial tachyarrhythmias after a 3-month blanking period. Three patients received additional ablation procedures for recurrent atrial arrhythmias. No non-PV triggers ablated during the previous procedure were observed.

Conclusion

A novel self-reference mapping technique is useful for eliminating non-PV triggers in terms of the short- and long-term success.

Figure 1. Distribution of non-PV triggers

Funding Acknowledgement

Type of funding source: None

Rab35 Targeting to the Plasma Membrane Is Dependent on the C-terminal Polybasic Cluster

Rab35, a member of the Rab GTPase family, has been implicated in various cellular processes including cell motility and membrane trafficking. Although Rab35 is localized to the plasma membrane, Rab proteins that are identified to have high sequence homology with Rab35 exhibit distinct subcellular localization patterns. Comparing the amino acid sequences between Rab35 and its family members revealed a significant variation in an approximate 30-amino acid region of the C-terminus. This suggests that this region determines the subcellular localization of individual Rab proteins. To confirm this hypothesis, we constructed Rab35–Rab10 chimera proteins by exchanging their C-terminal domains with one another. Confocal microscopy of RAW264 cells expressing EGFP-fused Rab35–Rab10 chimeras has indicated that the C-terminal region of Rab35 is critical for its plasma membrane localization. Furthermore, we were able to determine that a basic amino acid cluster exists in the C-terminal region of Rab35 and that Rab35 localization shifts to the Golgi membrane when the number of basic amino acids in this region is reduced. Thus, it is likely that the approximate 30-amino acid C-terminal region containing basic clusters is responsible for Rab35 plasma membrane localization and that its preferential localization depends on the number of basic amino acids.

P2691Excimer laser coronary angioplasty can achieve favorable clinical outocomes for in-stent restenosis lesion with neoatherosclerosis

Background

Recent reports revealed that residual area stenosis (% AS) ≤30% after lesion preparation is a suitable predictor for target lesion revascularization (TLR) after drug-coated balloon (DCB) treatment for in-stent restenosis (ISR). Excimer laser coronary angioplasty (ELCA) can obtain larger lumen area and may be more useful for lesion preparation than plain old ballooning (POBA). On the other hands, it has been reported that in-stent neoatherosclerosis (NA) is major cause of restenosis. It is unclear the correlation between NA of ISR and the effect of ELCA. Thus, we compared the influence of NA which was evaluated by optical coherence tomography (OCT) on % AS for ISR treatment between ELCA and DCB (ELCA) group and POBA and DCB (non-ELCA) group and their clinical outcome.

Methods

We enrolled 58 consecutive ISR lesions which were treated by OCT guidance between July 2014 and July 2018 in our hospital. The lesions were divided into NA and non-NA lesions according to OCT findings. In each lesion, we compared post procedural % AS and % AS change which was calculated by the difference between pre and post procedural % AS between ELCA and non-ELCA groups. In addition, we compared 8-month major advance cardiac events (MACE) defined by composite of binary restenosis and target lesion revascularization (TLR) between ELCA and non-ELCA group in NA lesions.

Results

There were 19 NA (33.3%) and 39 non-NA lesions. In NA lesions, ELCA group can obtain significantly lower % AS (p=0.02) and significantly larger % AS change (p<0.01) than non-ELCA group, but in non-NA lesions, % AS and %AS change were similar between ELCA and non-ELCA groups (table). In 8-month clinical outcome, non-ELCA group experienced MACE twice as much as ELCA group did. (31% vs 17%)

Results of %AS NA lesions (n=19) P value non-NA lesions (n=39) P value ELCA group (n=6) non-ELCA group (n=13) ELCA group (n=17) non-ELCA group (n=22) Post %AS (%) 2±21 26±25 0.02 7±29 23±19 0.07 %AS change (%) 71±15 38±19 <0.01 56±29 44±17 0.11

Conclusion

Although neoatherosclerosis is correlated with refractory restenosis, ELCA can improve residual area stenosis in neoatherosclerosis lesions and can achieve better clinical outcomes for in-stent neoatherosclerosis.

P3385Difference of vascular healing after percutaneous coronary intervention between 4 kinds of new generation drug-eluting stents: an optical coherence tomography analysis

Background

New generation drug eluting stents (DES) have improved target vessel failure as compared with early generation DES and bare metal stent. Contemporary several new generation DES are different each other regarding strut thickness and drug and polymer type. A little is known about which stent induces a more favorable vascular healing at follow up.

Purpose

In this study, we compared the vascular healing at 8-month follow up by optical coherence tomography (OCT) between 4 different kinds of new generation DES.

Methods

We enrolled 112 consecutive patients (121 lesions) who underwent PCI using 4 kinds of new generation DES including biodegradable-polymer everolimus-eluting stents (BP-EES), biodegradable-polymer sirolimus-eluting stents (BP-SES), durable-polymer everolimus-eluting stents (DP-EES) and durable-polymer zotarolimus-eluting stents (DP-ZES) and who underwent 8-month follow up angiogram and OCT between July 2016 and April 2018. We compared the OCT parameters including percentage of covered struts, uncovered struts, well-apposed and uncovered struts, malapposed strut and mean neointimal hyperplasia (NIH) thickness between them.

Results

BP-EES consisted of 29 lesions, BP-SES consisted of 25 lesions, DP-EES consisted of 38 lesions and DP-ZES consisted of 29 lesions. A total of 734 frames with 5163 struts in BP-EES, 481 frames with 4214 struts in BP-SES, 783 frames with 6119 struts in DP-EES and 583 frames with 4708 struts in DP-ZES were analyzed. As shown in a table, mean NIH thickness was significantly higher in BP-EES and BP-SES. Thus, we compared the OCT parameters between durable-polymer (DP) group including DP-ZES and DP-EES and biodegradable-polymer (BP) group including BP-EES and BP-SES. The percentage of uncovered struts was significantly lower and mean NIH thickness was significantly higher in BP group than DP group.

Results of OCT parameters BP-EES (n=29) BP-SES (n=25) DP-EES (n=38) DP-ZES (n=29) P value BP group (n=54) DP group (n=67) P value Covered struts (%) 89.5±13.6 92.4±8.6 85.5±17.5 85.0±17.7 0.29 90.9±11.6 85.3±17.4 0.08 Uncovered struts (%) 8.8±10.8 7.1±8.7 14.5±17.5 15.0±17.7 0.14 8.0±9.9 14.7±17.4 0.03 Well-apposed and uncovered struts (%) 7.9±9.9 5.9±7.7 11.7±13.1 12.3±14.0 0.15 7.0±8.9 11.9±13.4 0.04 Malapposed struts (%) 0.8±1.6 1.3±2.2 2.7±5.8 2.7±4.7 0.33 1.0±1.9 2.7±5.3 0.07 Mean NIH thickness (μm) 102±57 121±48 78±28 88±33 <0.01 111±53 82±31 <0.01

Conclusion

The present OCT study demonstrated that delayed neointimal healing characterized by the presence of uncovered struts and lower mean NIH thickness was less common in BP group than DP gruop. Biodegradable-polymer may be more favorable than durable-polymer from the point of view of vascular healing.

103Maximum calcium thickness is a useful predictor for under expansion after post dilatation in calcified lesions: optical coherence tomographic study

Background

Several reports have revealed that stent under expansion is associated with target lesion failure and calcified lesions usually induced inadequate stent expansion. Contemporary debulking devices such as rotational/orbital atherectomy can modify severe calcified lesions before stenting. However, it is uclear which calcium parameter is most useful predictor for stent expansion in the calcified lesions. Thus, we investigated useful calcium parameters correlating with stent expansion in the calcified lesions.

Methods

We enrolled 43 consecutive calcified lesions (43 patients) who underwent optical coherence tomography (OCT) guided percutaneous coronary intervention (PCI) between September 2016 and January 2019. We evaluated the lesions treated with post dilatation by non-compliant balloon due to stent under expansion after stenting. Exclusion criteria included acute coronary syndrome, in-stent restenosis and lesions without any calcium or treated with rotational atherectomy. If there were several calcium lesions in one patient, we selected maximum calcium angle lesion. Stent expansion defined as post-PCI lumen area divided by the values predicted by the manufactures compliance charts. We compared mean reference area, pre lesion area stenosis, calcium parameters including calcium arc, maximum thickness, area and longitudinal length in pre-PCI OCT evaluations with post-PCI stent expansion at that site.

Results

Maximum calcium thickness showed significant correlation with stent expansion, while the others did not show a significant correlation with stent expansion (table). The optimal thresholds of maximum calcium thickness for the prediction of acceptable stent expansion defined by 80% of the values predicted by the manufactures compliance charts was 870mm (area under curve (AUC): 0.65) (figure).

Results of OCT parameters Univariate analysis P value Mean reference area 0.41 Pre % area stenosis 0.16 Calcium parameters   Calcium arc 0.37   Calcium maximum thickness 0.04   Calcium area 0.20   Calcium longitudinal length 0.43

Conclusion

A maximum calcium thickness<870mm is a useful predictor for acceptable stent expansion after post dilatation in calcified lesions.

P3393Comparison of intermediate-term vascular response to new-generation biodegradable polymer and durable polymer-based drug-eluting stents: optical coherence tomographic study

Background

Over the last decade, drug-eluting stents (DES) have undergone substantial modifications with thinner struts and more biocompatible durable polymer (DP) or biodegradable polymer (BP). In DP-based DES, after drug elusion has been completed, DP remnants may trigger of local inflammatory vascular reactions and promote delayed healing, leading to accelerated neoatherosclerosis (NA). Thus, BPs have been developed to reduce the above-mentioned risks. Recently, poor strut coverage and in-stent NA are increasingly recognized the cause of late stent failure, but it is unclear whether BPs can reduce the incidence of NA and the poor stent coverage as compared to DPs.

Objectives

The purpose of this study was to compare the incidence of NA and the stent coverage using optical coherence tomography (OCT) between the DPs and the BPs.

Methods

Between July 2016 and April 2018, 127 consecutive patients with new-generation DES who underwent 8-month follow up OCT imaging were enrolled. Patients were divided into the two groups: DP group who had the new-generation durable polymer everolimus-eluting and zotarolimus-eluting stents and BP group who had the new-generation biodegradable polymer sirolimus-eluting and everolimus-eluting stents. We compared patient characteristics including hypertension, dyslipidemia and diabetes mellitus and 8-month follow up OCT findings including NA, uncovered struts and malapposed struts between the two groups.

Results

The DP group comprised 64 patients (50.4%. The incidence of NA, uncovered struts and malapposed struts were similar between the two groups (DPs vs BPs, 1.56% vs 7.94%, P=0.11; 7.80% vs 5.88%, P=0.16 and 2.76% vs 2.01%, P=0.43, respectively) (table). The other parameters were also similar between the two groups.

Table 1 DP group (n=64) BP group (n=63) P value Hypertension 44 (68.8%) 50 (79.4%) 0.2251 Dyslipidemia 39 (60.9%) 37 (58.7%) 0.8573 Diabetes mellitus 25 (39.1%) 30 (47.6%) 0.3731 8 month OCT follow up findings   Neoatherosclerosis 1 (1.6%) 5 (7.9%) 0.1147   Uncovered struts 7.8% (2.8–20.4) 5.9% (0.7–16.7) 0.1616   Malapposed struts 0.2% (0–2.8) 0% (0–2.8) 0.4392

Conclusions

The new-generation DP based-DES may have similar effects on vascular response compared to the new-generation BP-based DES during 8-month follow-up period.

P2689Irregular protrusion area is associated with incidence of cardiac events after implantation of new generation drug-eluting stents - optical coherence tomography study

Background

Several studies using optical coherence tomography (OCT) have shown that the prevalence of irregular protrusion was associated with the incidence of adverse cardiac events. However, the correlation between cardiac events and protrusion area is not well investigated.

Method

One hundred twenty-nine consecutive patients with 138 clesions with 2nd and 3rd generation drug-eluting stents (DES) which had pre-stenting and post-stenting OCT imaging between April 2016 and April 2018 were evaluated. We compared baseline characteristics, procedure findings and OCT findings including minimum stent area, protrusion type and maximum protrusion area between target lesion revascularization (TLR) group and non-TLR group.

Results

TLR occurred in 12 (9.3%) in 129 patients. The baseline characteristics and procedure findings were similar between TLR group and non-TLR group. Univariate analysis revealed that maximum irregular protrusion area was significantly larger (0.51 [0.00–0.63] vs 0.00 [0.00–0.27], p=0.036) in TLR group than non-TLR group. Receiver operating characteristic curve analysis revealed that the suitable cutoff value of maximum irregular protrusion area were 0.43mm2 for TLR. In multivariate analysis using the parameters with p value<0.10 determined by univariate analysis, maximum irregular protrusion (≥0.43mm2) and minimum stent area (MSA) were independently correlated with TLR (table).

Odd's ratio (95% CI) P value Major irregular protrusion (≥0.43mm2) 17.3 (3.63–82.6) <0.001 MSA 2.13 (1.15–3.93) 0.002

Conclusion

Major irregular protrusion (>0.43mm2) in post-stenting OCT findings may be a powerful predictor of TLR in the patients with new generation DES.

P1914Relationship between myocardial injury, inflammation and early, late recurrence after pulmonary vein isolation may be different between radiofrequency catheter ablation and cryoballoon ablation

Background

High sensitive cardiac troponin I (hs-TnI), subunit of cardiac troponin complex, is a sensitive and specific marker of myocardium injury as troponin T. Several studies showed hs-TnI was associated with worse cardiovascular outcomes but relationship between serum hs-TnI level in patients with atrial fibrillation (AF) after pulmonary vein isolation (PVI) and AF recurrence remains unclear.

Methods

We enrolled 444 consecutive AF patients who underwent PVI from May 2017 to September 2018. We investigated the difference of relationship between serum hs-TnI, inflammation markers at 48 hours after PVI and early or late recurrence of AF (ERAF, <3 months and LRAF, during 1 year after PVI in patients with AF) between radiofrequency ablation (RFA) group and cryoballoon ablation (CBA) group.

Results

RFA and CBA were performed in 328 and 116 patients, respectively. There were no significant differences in patient characteristics between RFA group and CBA group. Serum hs-TnI in RFA group was significantly lower than in CBA group (1.93 ng/ml±3.28 vs 5.08 ng/ml±4.29, p<0.001), while hs-CRP was significantly higher in RFA group than CB group (1.97±2.38 mg/dl vs 1.10±0.84 mg/dl, p<0.001). The incidence of ERAF was similar between the two groups (RFA group: 26.8% and CBA group: 21.6%, p=0.262). There was no significant difference of hs-TnI and hs-CRP between patients with ERAF and without ERAF (table). In 213 patients who were followed during 1 year (PVIs were performed from May 2017 to January 2018, RFA 149 and CBA 64 patients), there was no significant association between hs-TnI, hs-CRP and incidence of LRAF (table).

TnI and CRP between RFA and CBA RFA (n=328) CBA (n=116) P value hs-TnI 1.93±3.28 5.08±4.29 <0.001 hs-CRP 1.97±2.38 1.10±0.84 <0.001 3 months follow-up RFA (n=328) CBA (n=116) ERAF (+) ERAF (−) P value ERAF (+) ERAF (−) P value hs-TnI 1.68±1.90 2.02±3.66 0.410 5.03±3.17 5.10±4.56 0.943 hs-CRP 2.23±2.65 1.88±2.27 0.238 1.01±0.84 1.13±0.85 0.524 1 year follow-up RFA (n=149) CBA (n=64) LRAF (+) LRAF (−) P value LRAF (+) LRAF(−) P value hs-TnI 1.61±1.77 1.87±2.69 0.570 4.71±2.14 5.60±5.69 0.664 hs-CRP 2.18±2.24 1.92±2.24 0.550 1.12±0.64 1.12±0.98 0.991

Conclusion

CBA may cause more myocardial injury than RFA, on the contrary RFA may cause more inflammation than CBA. These markers did not affect ERAF and LRAF after PVI.

P1736A novel calcium parameter, calcium ratio, can predict minimum lumen area in calcified lesions: optical coherence tomographic study

Background

Several reports have revealed that minimum lumen area (MLA) is associated with target lesion failure even with newer-generation drug-eluting stents, and calcified lesions usually induced inadequate lumen area because of stent under expansion. Contemporary debulking devices such as rotational/orbital atherectomy can modify severe calcified lesions before stenting. However, there are no optimal criteria to indicate necessity for calcium modification to obtain adequate acute gain. Therefore, we investigated useful calcium parameters correlating with MLA in the calcified lesions after stenting.

Methods

We enrolled 71 consecutive calcified lesions (71 patients) who underwent optical coherence tomography (OCT) guided percutaneous coronary intervention (PCI) between September 2016 and January 2019. Exclusion criteria included acute coronary syndrome, in-stent restenosis and lesions without any calcium or treated with rotational atherectomy. If there were several calcium lesions in one patient, we selected maximum calcium angle lesion. We compared mean reference area, pre lumen area and various calcium parameters including calcium arc, maximum thickness, depth, area, longitudinal length and calcium ratio that was maximum calcium thickness divided by nearest reference diameter in disease-free segments as much as possible in pre-PCI OCT evaluation with post-PCI lumen area at that site by simple and multiple regression analysis.

Results

Calcium ratio was an independent predictor for post-PCI lumen area in addition to mean reference area, while the others were not associated with post-PCI lumen area (table).

Results of OCT parameters Univariate analysis Multivariate analysis P value P value β Mean reference area <0.01 <0.01 0.69 Pre lumen area <0.01 0.08 0.15 Cacium arc <0.01 0.58 −0.06 Calcium maximum thickness 0.62 Calcium ratio <0.01 0.01 −0.21 Calcium area 0.02 0.64 0.05 Calcium longitudinal length 0.60 Calcium depth 0.09

Conclusion

The novel calcium measurement, calcium ratio, may be a useful predictor for post-PCI lumen area for calcified lesions.

RhoC regulates the actin remodeling required for phagosome formation during FcγR-mediated phagocytosis

Phagosome formation is a complicated process that requires spatiotemporally regulated actin reorganization. We found that RhoC GTPase is a critical regulator of FcγR-mediated phagocytosis in macrophages. Our live-cell imaging revealed that RhoC, but not RhoA, is recruited to phagocytic cups engulfing IgG-opsonized erythrocytes (IgG-Es). RhoC silencing through RNAi, CRISPR/Cas-mediated RhoC knockout, and the expression of dominant-negative or constitutively active RhoC mutants suppressed the phagocytosis of IgG-Es. Moreover, RhoC-GTP pulldown experiments showed that endogenous RhoC is transiently activated during phagosome formation. Notably, actin-driven pseudopod extension, which is required for the formation of phagocytic cups, was severely impaired in cells expressing the constitutively active mutant RhoC-G14V, which induced abnormal F-actin accumulation underneath the plasma membrane. mDia1 (encoded by DIAPH1), a Rho-dependent actin nucleation factor, and RhoC were colocalized at the phagocytic cups. Similar to what was seen for RhoC, mDia1 silencing through RNAi inhibited phagosome formation. Additionally, the coexpression of mDia1 with constitutively active mutant RhoC-G14V or expression of active mutant mDia1-ΔN3 drastically inhibited the uptake of IgG-Es. These data suggest that RhoC modulates phagosome formation be modifying actin cytoskeletal remodeling via mDia1.

Rac1 switching at the right time and location is essential for Fcγ receptor-mediated phagosome formation

Lamellipodia are sheet-like cell protrusions driven by actin polymerization mainly through Rac1, a GTPase molecular switch. In Fcγ receptor-mediated phagocytosis of IgG-opsonized erythrocytes (IgG-Es), Rac1 activation is required for lamellipodial extension along the surface of IgG-Es. However, the significance of Rac1 deactivation in phagosome formation is poorly understood. Our live-cell imaging and electron microscopy revealed that RAW264 macrophages expressing a constitutively active Rac1 mutant showed defects in phagocytic cup formation, while lamellipodia were formed around IgG-Es. Because the activated Rac1 reduced the phosphorylation levels of myosin light chain, failure of the cup formation were probably due to inhibition of actin/myosin II contractility. Reversible photo-manipulation of the Rac1 switch in macrophages fed with IgG-Es could phenocopy two lamellipodial motilities: outward-extension and cup-constriction by Rac1 ON and OFF, respectively. In conjunction with FRET imaging of Rac1 activity, we provide a novel mechanistic model of phagosome formation spatiotemporally controlled by Rac1 switching within a phagocytic cup.

Cofilin contributes to phagocytosis of IgG-opsonized particles but not non-opsonized particles in RAW264 macrophages

Cofilin is an actin-binding protein that severs actin filaments. It plays a key role in regulating actin cytoskeletal remodeling, thereby contributing to diverse cellular functions. However, the involvement of cofilin in phagocytosis remains to be elucidated. We examined the spatiotemporal localization of cofilin during phagocytosis of IgG-opsonized erythrocytes, IgG-opsonized latex beads and non-opsonized latex beads. Live-cell imaging showed that GFP-cofilin accumulates in the sites of IgG-opsonized particle binding and in phagocytic cups. Moreover, immunofluorescence microscopy revealed that endogenous cofilin localizes to phagocytic cups engulfing IgG-opsonized particles, but not non-opsonized latex beads. Scanning electron microscopy demonstrated a notable difference in morphology between phagocytic structures in IgG-dependent and IgG-independent phagocytosis. In phagocytosis of IgG-opsonized particles, sheet-like pseudopodia extended along the surface of IgG-opsonized particles to form phagocytic cups. In contrast, in opsonin-independent phagocytosis, long finger-like filopodia captured non-opsonized latex beads. Importantly, non-opsonized beads sank into the cells without extending phagocytic cups. Our analysis of cofilin mutant expression demonstrates that phagocytosis of IgG-opsonized particles is enhanced in cells expressing wild-type cofilin or active mutant cofilin-S3A, whereas the uptake of non-opsonized latex beads is not. These data suggest that cofilin promotes actin cytoskeletal remodeling to form phagocytic cups by accelerating actin turnover and thereby facilitating phagosome formation. In contrast, cofilin is not involved in opsonin-independent phagocytosis of latex beads.

Diffuse Liver Metastasis of Small-Cell Lung Cancer Presenting as Acute Liver Failure and Diagnosed by Transjugular Liver Biopsy: A Rare Case in Whom Nodular Lesions Were Detected by Enhanced CT Examination

Small-cell lung cancer (SCLC) is a subgroup of lung cancer with a high frequency of liver metastasis, which is a predictor of poor prognosis. Diffuse liver metastases of SCLC with no visible nodular lesions in the liver when examined using computed tomography (CT) are relatively rare; however, a few cases with rapid progression to acute liver failure that were diagnosed after death have been reported. In this paper, we report a 63-year-old man with diffuse liver metastases of SCLC that were histologically diagnosed using a transjugular liver biopsy while the patient was alive, even though no lesions were visible during a contrast-enhanced CT examination.

Small GTPases and phosphoinositides in the regulatory mechanisms of macropinosome formation and maturation

Macropinosome formation requires the sequential activation of numerous signaling pathways that coordinate the actin-driven formation of plasma membrane protrusions (ruffles) and circular ruffles (macropinocytic cups), followed by the closure of these macropinocytic cups into macropinosomes. In the process of macropinosome formation, localized productions of phosphoinositides such as PI(4,5)P₂ and PI(3,4,5)P₃ spatiotemporally orchestrate actin polymerization and rearrangement through recruiting and activating a variety of actin-associated proteins. In addition, the sequential activation of small GTPases, which are known to be master regulators of the actin cytoskeleton, plays a pivotal role in parallel with phosphoinositides. To complete macropinosome formation, phosphoinositide breakdown and Rho GTPase deactivation must occur in appropriate timings. After the nascent macropinosomes are formed, phosphoinositides and several Rab GTPases control macropinosome maturation by regulating vesicle trafficking and membrane fusion. In this review, we summarize recent advances in our understanding of the critical functions of phosphoinositide metabolism and small GTPases in association with their downstream effectors in macropinocytosis.

Rac1-dependent lamellipodial motility in prostate cancer PC-3 cells revealed by optogenetic control of Rac1 activity

The lamellipodium, an essential structure for cell migration, plays an important role in the invasion and metastasis of cancer cells. Although Rac1 recognized as a key player in the formation of lamellipodia, the molecular mechanisms underlying lamellipodial motility are not fully understood. Optogenetic technology enabled us to spatiotemporally control the activity of photoactivatable Rac1 (PA-Rac1) in living cells. Using this system, we revealed the role of phosphatidylinositol 3-kinase (PI3K) in Rac1-dependent lamellipodial motility in PC-3 prostate cancer cells. Through local blue laser irradiation of PA-Rac1-expressing cells, lamellipodial motility was reversibly induced. First, outward extension of a lamellipodium parallel to the substratum was observed. The extended lamellipodium then showed ruffling activity at the periphery. Notably, PI(3,4,5)P₃ and WAVE2 were localized in the extending lamellipodium in a PI3K-dependent manner. We confirmed that the inhibition of PI3K activity greatly suppressed lamellipodial extension, while the ruffling activity was less affected. These results suggest that Rac1-induced lamellipodial motility consists of two distinct activities, PI3K-dependent outward extension and PI3K-independent ruffling.

Development of an automated fluorescence microscopy system for photomanipulation of genetically encoded photoactivatable proteins (optogenetics) in live cells

Photomanipulation of genetically encoded light-sensitive protein activity, also known as optogenetics, is one of the most innovative recent microscopy techniques in the fields of cell biology and neurobiology. Although photomanipulation is usually performed by diverting the photobleaching mode of a confocal laser microscope, photobleaching by the laser scanning unit is not always suitable for photoactivation. We have developed a simple automated wide-field fluorescence microscopy system for the photomanipulation of genetically encoded photoactivatable proteins in live cells. An electrically automated fluorescence microscope can be controlled through MetaMorph imaging software, making it possible to acquire time-lapse, multiwavelength images of live cells. Using the journal (macro recording) function of MetaMorph, we wrote a macro program to change the excitation filter for photoactivation and illumination area during the intervals of image acquisition. When this program was run on the wide-field fluorescence microscope, cells expressing genetically encoded photoactivatable Rac1, which is activated under blue light, showed morphological changes such as lamellipodial extension and cell surface ruffling in the illuminated region. Using software-based development, we successfully constructed a fully automated photoactivation microscopy system for a mercury lamp-based fluorescence microscope.

Spatiotemporal Localization of Rab20 in Live RAW264 Macrophages during Macropinocytosis

Rab20 is a member of the Rab GTPase family, but its implication in macropinocytosis is unclear. We examined the spatiotemporal localization of Rab20 in RAW264 macrophages by the live-cell imaging of fluorescent protein-fused Rab20. It was shown that Rab20 was transiently associated with macropinosomal membranes. During the early stage of macropinosome formation, Rab20 was slightly localized on the circular ruffles (macropinocytic cups), the precursor forms of macropinosomes, and was increasingly recruited to the newly formed macropinosomes. Although Rab20 was colocalized with Rab5 and Rab21 on macropinosomal membranes, the association of Rab20 with macropinosomes persisted even after the dissociations of Rab5 and Rab21 from macropinosomal membranes. Rab20 was then colocalized with Rab7 and Lamp1, late endosomal/lysosomal markers, on macropinosomes for a while. Our data indicate that Rab20 is a novel component of macropinocytic pathway and functions at long-standing stages from early to late macropinosome maturation.

Rab20 regulates phagosome maturation in RAW264 macrophages during Fc gamma receptor-mediated phagocytosis

Rab20, a member of the Rab GTPase family, is known to be involved in membrane trafficking, however its implication in FcγR-mediated phagocytosis is unclear. We examined the spatiotemporal localization of Rab20 during phagocytosis of IgG-opsonized erythrocytes (IgG-Es) in RAW264 macrophages. By the live-cell imaging of fluorescent protein-fused Rab20, it was shown that Rab20 was transiently associated with the phagosomal membranes. During the early stage of phagosome formation, Rab20 was not localized on the membranes of phagocytic cups, but was gradually recruited to the newly formed phagosomes. Although Rab20 was colocalized with Rab5 to some extent, the association of Rab20 with the phagosomes persisted even after the loss of Rab5 from the phagosomal membranes. Then, Rab20 was colocalized with Rab7 and Lamp1, late endosomal/lysosomal markers, on the internalized phagosomes. Moreover, our analysis of Rab20 mutant expression revealed that the maturation of phagosomes was significantly delayed in cells expressing the GDP-bound mutant Rab20-T19N. These data suggest that Rab20 is an important component of phagosome and regulates the phagosome maturation during FcγR-mediated phagocytosis.

Can health systems be enhanced for optimal health services through disease-specific programs? Results of field studies in Viet Nam and Cambodia

Developing better health systems is the key to delivering optimal health services, although more evidence of effective strategies to do so is needed. Field surveys were conducted in Viet Nam and Cambodia to identify best practices in addressing health system bottlenecks to scale up disease control programs. The two countries were compared over time using a framework for analysis developed by the authors. In Viet Nam, a health system was in place for decades at the central to municipal levels, although it was fragile until the 1990s, when the government started taking measures. In Cambodia, the previous health system had been destroyed during previous internal conflict. In the post-conflict period, the health system was rebuilt with support for programs followed by centralization of health services. In different settings, different measures were taken to deal with similar bottlenecks. In Cambodia, vertical programs were dominant, so the government sought to centralize drug management to deal with shortages of essential drugs, while Viet Nam sought to mobilize resources to ensure drug distribution at all levels. This study shows there is no single successful approach to health systems, and a systemic approach needs to be taken because elimination of one bottleneck may reveal another. Efforts to enhance disease-specific programs may not always contribute to overall enhancement of the health system, and the best possible approach may not be the same in different countries. Further study is needed to explore common issues and principles for effective strategies to enhance health systems in different contexts.

Rab35 regulates phagosome formation through recruitment of ACAP2 in macrophages during FcγR-mediated phagocytosis

Phagosome formation and subsequent maturation are complex sequences of events that involve actin cytoskeleton remodeling and membrane trafficking. Here, we demonstrate that the Ras-related protein Rab35 is involved in the early stage of FcγR-mediated phagocytosis in macrophages. Live-cell image analysis revealed that Rab35 was markedly concentrated at the membrane where IgG-opsonized erythrocytes (IgG-Es) are bound. Rab35 silencing by RNA interference (RNAi) or the expression of GDP- or GTP-locked Rab35 mutant drastically reduced the rate of phagocytosis of IgG-Es. Actin-mediated pseudopod extension to form phagocytic cups was disturbed by the Rab35 silencing or the expression of GDP-Rab35, although initial actin assembly at the IgG-E binding sites was not inhibited. Furthermore, GTP-Rab35-dependent recruitment of ACAP2, an ARF6 GTPase-activating protein, was shown in the phagocytic cup formation. Concomitantly, overexpression of ACAP2 along with GTP-locked Rab35 showed a synergistic inhibitory effect on phagocytosis. It is likely that Rab35 regulates actin-dependent phagosome formation by recruiting ACAP2, which might control actin remodeling and membrane traffic through ARF6.

Dynamic changes in the spatiotemporal localization of Rab21 in live RAW264 cells during macropinocytosis

Rab21, a member of the Rab GTPase family, is known to be involved in membrane trafficking, but its implication in macropinocytosis is unclear. We analyzed the spatiotemporal localization of Rab21 in M-CSF-stimulated RAW264 macrophages by the live-cell imaging of fluorescent protein-fused Rab21. It was demonstrated that wild-type Rab21 was transiently associated with macropinosomes. Rab21 was recruited to the macropinosomes after a decrease in PI(4,5)P₂ and PI(3,4,5)P₃ levels. Although Rab21 was largely colocalized with Rab5, the recruitment of Rab21 to the macropinosomes lagged a minute behind that of Rab5, and preceded that of Rab7. Then, Rab21 was dissociated from the macropinosomes prior to the accumulation of Lamp1, a late endosomal/lysosomal marker. Our analysis of Rab21 mutants revealed that the GTP-bound mutant, Rab21-Q78L, was recruited to the macropinosomes, similarly to wild-type Rab21. However, the GDP-bound mutant, Rab21-T33N, did not localize on the formed macropinosomes, suggesting that the binding of GTP to Rab21 is required for the proper recruitment of Rab21 onto the macropinosomes. However, neither mutation of Rab21 significantly affected the rate of macropinosome formation. These data indicate that Rab21 is a transient component of early and intermediate stages of macropinocytosis, and probably functions in macropinosome maturation before fusing with lysosomal compartments.

Characterization of Rab21-positive tubular endosomes induced by PI3K inhibitors

We found that wortmannin, a potent phosphoinositide 3-kinase (PI3K) inhibitor, markedly induced the formation of Rab21-positive tubular compartments in A431 cells. By time-lapse fluorescence microscopy of live cells co-expressing fluorescent protein-fused Rab21 and other marker proteins, it was shown that the Rab21-positive tubules in wortmannin-treated cells were derived from Rab5-positive early endosomes, but not from late endosomes, recycling endosomes, lysosomes or the trans-Golgi network. The formation of Rab21-positive tubules was very dynamic and required microtubules. Rab21-positive tubules were also formed by the treatment of cells with 3-methyladenine (3-MA), which inhibits class III PI3K rather than class I PI3K. Furthermore, the loss of PI(3)P correlated with the tubulation of Rab21-positive endosomes in cells co-expressing fluorescent protein-fused Rab21 and a tandem FYVE domain. These results suggest that the lowering of PI(3)P as a result of class III PI3K inhibition may be an important cue for the morphological change of Rab21-positive early endosomes from vesicular to tubular form.

Phosphoinositide metabolism during membrane ruffling and macropinosome formation in EGF-stimulated A431 cells

Inhibitors of phosphoinositide 3-kinase (PI3K) were found to perturb macropinosome formation without affecting the membrane ruffling and actin polymerization in epidermal growth factor-stimulated A431 cells. Live-cell imaging and quantitative image analysis of the fluorescence intensity ratio of the YFP-tagged phospholipase Cdelta1-pleckstrin homology domain (YFP-PLC-PH) relative to membrane-targeted CFP (CFP-Mem) demonstrated that the concentration of PI(4,5)P(2) in the membrane ruffles forming macropinocytic cups increased to more than double that in planar plasma membranes. The PI(4,5)P(2) level in the membrane reached its maximum just before macropinosome closure and rapidly fell as the macropinocytic cups closed. In contrast, the PI(3,4,5)P(3) concentrations visualized based on the YFP-Akt-PH or YFP-Bruton's tyrosine kinase (Btk)-PH/CFP-Mem ratio increased locally at the site of macropinosome formation and peaked at the time of macropinosome closure. The kinetics of PI(4,5)P(2) and PI(3,4,5)P(3) appeared to be mechanistically linked to actin remodeling during macropinocytosis. From the pharmacological data using inhibitors and synthetic phosphoinositides and other data, it could be concluded that both PI(4,5)P(2) elimination and PI(3,4,5)P(3) production by PI3K might be crucial for macropinosome formation from membrane ruffles. This study emphasizes that locally controlled levels of phosphoinositides are important for regulating the function of actin-binding proteins which effect changes in the membrane architecture.