An extremely energetic cosmic ray observed by a surface detector array

Cosmic rays are energetic charged particles from extraterrestrial sources, with the highest-energy events thought to come from extragalactic sources. Their arrival is infrequent, so detection requires instruments with large collecting areas. In this work, we report the detection of an extremely energetic particle recorded by the surface detector array of the Telescope Array experiment. We calculate the particle's energy as [Formula: see text] (~40 joules). Its arrival direction points back to a void in the large-scale structure of the Universe. Possible explanations include a large deflection by the foreground magnetic field, an unidentified source in the local extragalactic neighborhood, or an incomplete knowledge of particle physics.

Improved uniform persistence for partially diffusive models of infectious diseases: cases of avian influenza and Ebola virus disease

Past works on partially diffusive models of diseases typically rely on a strong assumption regarding the initial data of their infection-related compartments in order to demonstrate uniform persistence in the case that the basic reproduction number $ \mathcal{R}_0 $ is above 1. Such a model for avian influenza was proposed, and its uniform persistence was proven for the case $ \mathcal{R}_0 > 1 $ when all of the infected bird population, recovered bird population and virus concentration in water do not initially vanish. Similarly, a work regarding a model of the Ebola virus disease required that the infected human population does not initially vanish to show an analogous result. We introduce a modification on the standard method of proving uniform persistence, extending both of these results by weakening their respective assumptions to requiring that only one (rather than all) infection-related compartment is initially non-vanishing. That is, we show that, given $ \mathcal{R}_0 > 1 $, if either the infected bird population or the viral concentration are initially nonzero anywhere in the case of avian influenza, or if any of the infected human population, viral concentration or population of deceased individuals who are under care are initially nonzero anywhere in the case of the Ebola virus disease, then their respective models predict uniform persistence. The difficulty which we overcome here is the lack of diffusion, and hence the inability to apply the minimum principle, in the equations of the avian influenza virus concentration in water and of the population of the individuals deceased due to the Ebola virus disease who are still in the process of caring.

High-energy molecular-frame photoelectron angular distributions: a molecular bond-length ruler

We present a study on molecular-frame photoelectron angular distributions (MFPADs) of small molecules using circularly polarized synchrotron light. We find that the main forward-scattering peaks of the MFPADs are slightly tilted with respect to the molecular axis. This tilt angle is directly connected to the molecular bond length by a simple, universal formula. We apply the derived formula to several examples of MFPADs of C 1s and O 1s photoelectrons of CO, which have been measured experimentally or obtained by means of ab initio modeling. In addition, we discuss the influence of the back-scattering contribution that is superimposed over the analyzed forward-scattering peak in the case of homo-nuclear diatomic molecules such as N₂.

Cell death signalling is competitively but coordinately regulated by repressor-type and activator-type ethylene response factors in tobacco (Nicotiana tabacum) plants

Ethylene response factors (ERFs) comprise one of the largest transcription factor families in many plant species. Tobacco (Nicotiana tabacum) ERF3 (NtERF3) and other ERF-associated amphiphilic repression (EAR) motif-containing ERFs are known to function as transcriptional repressors. NtERF3 and several repressor-type ERFs induce cell death in tobacco leaves and are also associated with a defence response against tobacco mosaic virus (TMV). We investigated whether transcriptional activator-type NtERFs function together with NtERF3 in the defence response against TMV infection by performing transient ectopic expression, together with gene expression, chromatin immunoprecipitation (ChIP) and promoter analyses. Transient overexpression of NtERF2 and NtERF4 induced cell death in tobacco leaves, albeit later than that induced by NtERF3. Fusion of the EAR motif to the C-terminal end of NtERF2 and NtERF4 abolished their cell death-inducing ability. The expression of NtERF2 and NtERF4 was upregulated at the early phase of N gene-triggered hypersensitive response (HR) against TMV infection. The cell death phenotype induced by overexpression of wild-type NtERF2 and NtERF4 was suppressed by co-expression of an EAR motif-deficient form of NtERF3. Furthermore, ChIP and promoter analyses suggested that NtERF2, NtERF3 and NtERF4 positively or negatively regulate the expression of NtERF3 by binding to its promoter region. Overall, our results revealed the cell death-inducing abilities of genes encoding activator-type NtERFs, including NtERF2 and NtERF4, suggesting that the HR-cell death signalling via the repressor-type NtERF3 is competitively but coordinately regulated by these NtERFs.

POS0670 EVALUATION OF UPADACITINIB IN RHEUMATOID ARTHRITIS PATIENTS WITH INADEQUATE RESPONSE TO FIRST-GENERATION JANUS KINASE INHIBITORS

Background

Janus kinase inhibitors (JAKi) are effective in the treatment of patients with difficult-to-treat rheumatoid arthritis (D2T RA), regardless of previous use of biological disease-modifying antirheumatic drugs (bDMARDs), and receive equal billing with biological therapies in the latest version of the EULAR recommendations for treatment of RA1. However, as with bDMARDs, cases of discontinuation due to intolerance or inadequate response have been observed in patients treated with the so-called first-generation JAKi, leading to the development of a new generation of JAKi that aims to maximize efficacy and improve safety by enhancing kinase selectivity. The results of randomized controlled trials and meta-analyses suggest that the efficacy and safety of Upadacitinib (UPA) treatment are favorable. Although there have been no head-to-head trials between JAKi, a matched-adjusted indirect comparative study has shown a difference in efficacy between JAKi2, suggesting that the new generation of JAKi may be effective in rheumatoid arthritis patients with intolerance or inadequate response to first-generation JAKi. It is already apparent that a clear need exists for a JAK-IR trial to give guidance in those difficult patients who are JAKi non-responders3.

Objectives

To evaluate real world efficacy of a second-generation JAK1-selective JAKi UPA in single-center cohort of RA patients who had discontinued first-generation JAKi.

Methods

Patients with RA who had discontinued tofacitinib and/or baricitinib due to inadequate response or intolerance, regardless of whether they had used bDMARDs or not, were eligible for the study if they had received UPA by October 2021 and had been followed up for at least 12 weeks. Endpoints were Kaplan-Meier survival rate with inadequate response or intolerance as reasons for discontinuation, various disease activity assessments (DAS28-ESR, SDAI, CDAI, etc.), and patient reported outcomes (visual analogue scales (VASs) such as pain and stiffness, HAQ-DI, FACIT-Fatigue Scale, etc.) at 12 weeks. In addition, the reasons for discontinuation were investigated.

Results

Fifty-one patients were included in the study, all of whom had D2T RA and had used at least one bDMARD as well as JAKi. The mean (median) age was 72.7 (77) years, disease duration 18.0 (17) years, number of bDMARDs used 3.34 (3), number of JAKi used 1.3(1), 5 patients with methotrexate, 6 patients with prednisolone, and DAS28-ESR 3.83 (3.9). At 12 weeks, the overall survival rate was 94% (94.6% in 37 cases used as 2nd JAKi and 92.9% in 14 cases used as 3rd JAKi). For reference, there was no significant difference from the 100% of the 15 cases used as the 1st JAKi (P=0.49). DAS28-ESR <3.2 and <2.6 were achieved in 60.8% and 29.4%, VASs for pain and stiffness decreased by a mean of 12.9 mm (9 mm) and 12.1 mm (7 mm), respectively, and FACIT-Fatigue scale improved by a mean of 3.0 (1). The reasons for discontinuation in the three patients were inadequate efficacy in two and leg cramps due to venous thromboembolism in one.

Conclusion

UPA is more selective for JAK1 than first generation JAKi, and is expected to reduce adverse reactions caused by inhibition of JAK family members other than JAK1. The present study suggests that UPA is effective and well tolerated, regardless of the number and type of first-generation JAKi used in the past, albeit for a short period of time. Limitations include the small number of cases and the short time frame for discussing adverse reactions.

References

[1]Smolen JS, Landewé BM, Bijlsma WJ et al., EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2019 update. Ann Rheum Dis 2020;79:685–699.

[2]Christopher JE, Ruta S, Vishvas G et al. A Matching-Adjusted Indirect Comparison of Upadacitinib Versus Tofacitinib in Adults with Moderate-to-Severe Rheumatoid Arthritis. Rheumatol Ther 2021; 8:167–181.

[3]Peter Nash, Clinical use of Jak 1 inhibitors for rheumatoid arthritis. Rheumatology, Volume 60, Issue Supplement_2, May 2021, Pages ii31–ii38

Disclosure of Interests

None declared

Investigating charge-up and fragmentation dynamics of oxygen molecules after interaction with strong X-ray free-electron laser pulses

The X-ray-induced charge-up and fragmentation process of a small molecule is examined in great detail by measuring the molecular-frame photoelectron interference pattern in conjunction with other observables in coincidence.

AB0252 EFFICACY OF A SECOND JANUS KINASE INHIBITOR THAT WAS SWITCHED FOR DIFFICULT-TO-TREAT RA IN CLINICAL PRACTICE

Background:

In clinical practice, when refractory rheumatoid arthritis (RA) is present, of which the definition implies previous use of at least two biologic disease-modifying antirheumatic drugs (bDMARDs) (generally tumour necrosis factor inhibitors (TNFis)), the next treatment choice often made is a bDMARD of another class (non-TNFis) [1]. However, patients who are inadequately responding to bDMARDs need new treatment options because subsequent bDMARDs treatment reduces their response [2]. Janus Kinase inhibitors (JAKis) are the first targeted synthetic DMARDs (tsDMARD) licensed for the treatment of RA with comparable efficacy to bDMARDs. Unlike the single cytokine targeting approach of bDMARDs, JAKis are specifically designed to inhibit intracellular signalling molecules common to the receptors of multiple inflammatory cytokines implicated in RA pathogenesis. The choice of therapeutic agents for refractory RA is increasing, and its efficacy is expected. On the other hand, it is also true that some patients discontinued JAKis at a rate that cannot be overlooked because of insufficient efficacy. Difficult-to-treat (D2T) RA is defined as refractory to two or more b/ts DMARDs with different mechanisms of action, with active and progressive disease, as published by Eular(3)

Objectives:

To evaluate real world efficacy of approved JAKis switching in patients with D2T RA who were unable to control their disease activity due to insufficient efficacy despite the sequential use of multiple bDMARDs and JAKis, focusing on the drug retention rate.

Methods:

In our hospital, RA was diagnosed according to the 1987 or 2010 classification criteria, and when two or more bDMARDs (including both TNFis and non-TNFis) were inadequately effective, it was defined as D2T RA. We retrospectively investigated patients who switched to JAKis for D2T RA. The drug retention rate was investigated by the Kaplan-Meier method, and the difference was tested by the Logrank test.

Results:

The 1-year retention rate of JAKis for D2T RA was 50.8% in TOF 38 cases [28 women, age average 70.2 years, disease duration average 12.4 years, past bDMARDs use average 3.5 drugs, MTX combination 9 cases, DAS28 ESR average 4.11] and 66.3% in BAR 35 cases [26 cases, 73.0 years old, 14.8 years, 4.17 agents, 9 cases, 3.68], and there was no significant difference (P = 0.30). Among them, there were 17 cases [11 cases, 70.6 years old, 13.5 years, 4.18 drugs, 2 cases, 3.65] of switching between JAKis, all of which were switching from TOF to BAR. The 1-year retention rate was 45.8% [reason for discontinuation: insufficient effect in 3 cases, adverse events in 6 cases], which was not significantly different but tended to be lower than 72.7% [reason for discontinuation: insufficient effect in 1 case, adverse event in 2 cases, patient’s convenience in 1 case] in 16 patients [13 cases, 76.3 years old, 17.1 years, 3.19 drugs, 7 cases, 3.69] who received BAR as the first JAKi for D2T RA patients (P = 0.089).

Conclusion:

Although the number of cases is small in the retrospective survey, it is suggested that the retention rate of BAR switched to D2T RA may be slightly lower in patients with a history of TOF discontinuation due to insufficient efficacy than in JAKi naive patients. It is expected that the number of new JAKi usage cases will increase in the future, and it is necessary to consider switching between other JAKis in addition to switching from BAR to TOF.

References:

[1]Smolen JS, Landewe R, Bijlsma J et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2016 update. Ann Rheum Dis 2017;76:960_77.

[2]Rendas-Baum R, Wallenstein GV, Koncz T et al. Evaluating the efficacy of sequential biologic therapies for rheumatoid arthritis patients with an inadequate response to tumor necrosis factor-α inhibitors. Arthritis Res Ther 2011;13:R25.

[3]Nagy G, et al. EULAR definition of difficult-to-treat rheumatoid arthritis. Ann Rheum Dis 2021;80:31–35. doi:10.1136/annrheumdis-2020-217344.

Disclosure of Interests:

None declared

POS0088 EFFICACY OF JANUS KINASE INHIBITORS FOR DIFFICULT-TO-TREAT RA IN CLINICAL PRACTICE

Background:

In 20-30% of rheumatoid arthritis (RA) patients, the first biologic disease-modifying antirheumatic drugs (bDMARDs) (generally tumour necrosis factor inhibitors (TNFis)) is ineffective, and among the patients who do respond to therapy, 20% is faced with secondary ineffectiveness within the first 2 years of treatment [1]. In practice, when refractory RA is present, of which the definition implies previous use of at least two bDMARDs (generally TNFis), the next treatment choice often made is a bDMARD of another class (non-TNFis) [2]. On the other hand, patients who are inadequately responding to bDMARDs need new treatment options because subsequent bDMARD treatment reduces their response [3]. Janus Kinase inhibitors (JAKis) are the first targeted synthetic DMARDs (tsDMARD) licensed for the treatment of RA with comparable efficacy to bDMARDs. Unlike the single cytokine targeting approach of bDMARDs, JAKis are specifically designed to inhibit intracellular signalling molecules common to the receptors of multiple inflammatory cytokines implicated in RA pathogenesis.

Objectives:

Difficult-to-treat (D2T) RA is defined as refractory to two or more b/ts DMARDs with different mechanisms of action, with active and progressive disease, as published by Eular(4). We evaluated real world efficacy of approved JAKis and factors that may help to continue them in patients with D2T RA.

Methods:

Patients who had inadequate response to two or more bDMARDs (including both TNFis and non-TNFis) at our hospital by December 2019 were defined as D2T RA, and patients who switched to JAKis were retrospectively investigated. The drug retention rate was determined by Kaplan-Meier method, and the difference was tested by Logrank test. Multiple regression analysis was used as the statistical method to predict continuation of JAKis for more than 1 year, with patient background (age, gender, during the disease, number of bDMARDs used, with or without methotrexate and/or glucocorticoids, disease activity score assessing 28 joints using erythrocyte sedimentation rate’ presence of rheumatoid factor/anti-CCP antibody, matrix metalloproteinase 3 value, Health Assessment Questionnaire disability index) at the time of initiation as an explanatory variable.

Results:

A total of 915 bDMARDs had been administered to 394 RA patients. The retention rate of bDMARDs and the number of bDMARDs used were 89.3% and 1.48 bDMARDs at 1 year, 67.7% and 2.27 bDMARDs at 5 years, and 52.0% and 3.15 bDMARDs at 10 years, respectively. The retention rate of JAKis at 1 year was 60.2% in 65 patients with tofacitinib (TOF) and 67.2% in 70 patients with baricitinib (BAR) (P=0.38). Among them, the drug retention rate in D2T RA patients was 50.8% in 38 TOF patients and 66.3% in 35 BAR patients with no significant difference (P=0.30). There were no patient background factors that significantly predicted continuation at 1 year for any JAKis.

Conclusion:

Despite the limited number of patients and the retrospective nature of the study, TOF and BAR were shown to be effective options for D2T RA, regardless of patient background such as disease activity or number of bDMARDs used. Other JAKis and switches between JAKis need to be investigated in the future.

References:

[1]Schaeverbeke T, Truchetet ME, Kostine M et al. Immunogenicity of biologic agents in rheumatoid arthritis patients: lessons for clinical practice. Rheumatology 2016;55:210_20.

[2]Smolen JS, Landewe R, Bijlsma J et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2016 update. Ann Rheum Dis 2017;76:960_77.

[3]Rendas-Baum R, Wallenstein GV, Koncz T et al. Evaluating the efficacy of sequential biologic therapies for rheumatoid arthritis patients with an inadequate response to tumor necrosis factor-α inhibitors. Arthritis Res Ther 2011;13:R25.

[4]Nagy G, et al. EULAR definition of difficult-to-treat rheumatoid arthritis. Ann Rheum Dis 2021;80:31–35. doi:10.1136/annrheumdis-2020-217344.

Disclosure of Interests:

None declared

Neutropenia and survival outcomes in metastatic colorectal cancer patients treated with trifluridine/tipiracil in the RECOURSE and J003 trials

Background:

The phase II J003 (N = 169) and phase III RECOURSE (N = 800) trials demonstrated a significant improvement in survival with trifluridine (FTD)/tipiracil (TPI) versus placebo in patients with refractory metastatic colorectal cancer. This post hoc analysis investigated pharmacokinetic data of FTD/TPI exposure and pharmacodynamic markers, such as chemotherapy-induced neutropenia (CIN) and clinical outcomes.

Patients and methods:

A total of 210 patients from RECOURSE were enrolled in this substudy. A limited sampling approach was used, with three pharmacokinetic samples drawn on day 12 of cycle 1. Patients were categorized as being above or below the median area under the plasma concentration–time curve (AUC) for FTD and TPI. We conducted a post hoc analysis using the entire RECOURSE population to determine the correlations between CIN and clinical outcome. We then carried out a similar analysis on the J003 trial to validate the results.

Results:

In the RECOURSE subset, patients in the high FTD AUC group had a significantly increased CIN risk. Analyses of the entire population demonstrated that FTD/TPI-treated patients with CIN of any grade in cycles 1 and 2 had significantly longer median overall survival (OS) and progression-free survival (PFS) than patients who did not develop CIN and patients in the placebo group. Patients who required an FTD/TPI treatment delay had increased OS and PFS versus those in the placebo group and those who did not develop CIN. Similar results were obtained in the J003 cohort.

Conclusions:

In RECOURSE, patients with higher FTD drug exposure had an increased CIN risk. FTD/TPI-treated patients who developed CIN had improved OS and PFS versus those in the placebo group and those who did not develop CIN. Similar findings were reported in the J003 cohort, thus validating the RECOURSE results. The occurrence of CIN may be a useful predictor of treatment outcomes for FTD/TPI-treated patients.

ClinicalTrials.gov identifier:

NCT01607957 (RECOURSE).

Japan Pharmaceutical Information Center number:

JapicCTI-090880 (J003).

Oxaliplatin-based adjuvant chemotherapy duration (3 versus 6 months) for high-risk stage II colon cancer: the randomized phase III ACHIEVE-2 trial

BACKGROUND

Oxaliplatin-based adjuvant chemotherapy may be associated with debilitating peripheral sensory neuropathy (PSN) in patients with high-risk stage II colon cancer. This open-label, multicenter, randomized phase III trial was conducted as a prospective pooled analysis to investigate the non-inferiority of 3 versus 6 months of adjuvant oxaliplatin-based chemotherapy.

PATIENTS AND METHODS

From 12 February 2014 to 31 January 2017, 525 Asian patients with high-risk stage II colon cancer were randomly assigned to 3- and 6-month treatment arms. The treatment consisted of either modified fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) or capecitabine combined with oxaliplatin (CAPOX). The primary end point was disease-free survival (DFS). The secondary end points were treatment compliance and safety.

RESULTS

Of the 525 randomized patients, 11 were not treated. Among the 514 participating patients (255 in the 3-month arm; 259 in the 6-month arm), 432 (84%) received CAPOX, and 184 (36%) presented with T4 as a high-risk factor for recurrence. The 3-year DFS rate was 88.2% in the 3-month arm and 87.9% in the 6-month arm [hazard ratio (HR), 1.12; 95% confidence interval (CI), 0.67-1.87]. With CAPOX, the 3-year DFS rate was 88.2% in the 3-month arm and 88.4% in the 6-month arm (HR, 1.13; 95% CI, 0.65-1.96). The discontinuation rate in the 3- and 6-month arms was 10% and 31% for mFOLFOX6 (P = 0.0193), and 15% and 35% for CAPOX (P < 0.0001), respectively. The incidence of grade ≥2 PSN was significantly lower in the 3-month arm than in the 6-month arm (16% and 43%, respectively, P < 0.0001).

CONCLUSIONS

Three months of combination therapy presented significantly less grade ≥2 PSN than the respective 6-month regimen. The shortened therapy duration did not affect the 3-year DFS rate, suggesting that a 3-month course of CAPOX can be an effective treatment option.

CLINICAL TRIAL INFORMATION

UMIN Clinical Trials Registry, UMIN000013036 and Japan Registry of Clinical Trials, jRCTs031180128.

AB0350 EFFICACY OF ADDING IGURATIMOD THERAPY IN RHEUMATOID ARTHRITIS PATIENTS WHO HAD INADEQUATE RESPONSE TO BIOLOGIC DMARDS

Background:

Iguratimod (IGU) was newly approved in Japan in June 2012 and recommended by JCR guideline 2014 in the treatment of rheumatoid arthritis (RA). Although there have been efficacy of monotherapy and concomitant MTX in clinical trials, however, there have been no reports of concomitant biologic DMARDs (Bio).

Objectives:

we investigated efficacy of concomitant IGU therapy in RA patients who had inadequate response to Bio at the author’s institution.

Methods:

Subjects were 107 patients adding IGU who had inadequate response to Bio from Janually 2014 to October 2018. Previous treatment Bio. was ADA. And baseline mean concomitant MTX was 12.3 mg/week). And baseline characteristics were Mean age 53.8 years, mean duration of illness 5.5 years, corticosteroid use 9.3%(mean 3.1mg/day).

The course of DAS28, SDAI, CDAI and remission rates were analyzed.

Results:

Mean DAS28-ESR, SDAI, CDAI were significantly decreased from the initiation of IGU treatment at 24 weeks (3.1→2.3, 7.1→2.7, 6.5→2.4), at 52 weeks (2.1, 2.4, 2.0). Remission rates of DAS28-ESR, SDAI, CDAI were 69.2%, 68.2%, 70.1% at 24 weeks, 74.8%, 78.5%, 79.4% at 52 weeks. There were no side-effect that must be stopped after adding IGU.

Conclusion:

IGU might be a new RA treatment option for aiming remission in patients who had inadequate response to Bio.

References:

[1]Hara M et al: Safety and efficacy of combination therapy of iguratimod with methotrexate for patients with active rheumatoid arthritis with an inadequate response to methotrexate: an open-label extension of a randomized, double-blind, placebo-controlled trial. Mod Rheumatol. 2014; 24: 410—418.

Disclosure of Interests:

None declared

Intergenerational fluctuations in colour morph frequencies may maintain elytral polymorphisms in the ladybird beetle Cheilomenes sexmaculata (Coleoptera: Coccinellidae)

Phenotypic polymorphisms are found in a wide array of taxa, and unravelling the mechanisms that maintain them is of great interest to evolutionary and ecological biologists. Temporal environmental heterogeneity may play a role in the maintenance of polymorphisms but is poorly understood. In the present study, we analysed trends in intergenerational elytral colour morph frequencies in relation to changes in fitness and life history traits (i.e. body size, mortality, fecundity, hatching rate and mate preference) in the ladybird beetle Cheilomenes sexmaculata (Coleoptera: Coccinellidae). A long-term field survey spanning nine years showed that the frequency of dark morphs increases over winter and then decreases in spring. Dark morphs may have an advantage in winter due to their higher tolerance of low temperatures compared with light morphs. Light-morph females were heavier in winter than dark-morph females. They also mated more frequently and had higher hatching rates, potentially causing an increase in light morphs in spring. These results suggest that fluctuations in morph frequencies resulting from the conflicting directions of selection pressures between overwintering and spring generations may help to maintain genetic polymorphism.

P1016Novel surgical ablation technique using ultrasonic scalpel for atrial fibrillation in mitral valve surgery

Objective

Radiofrequency, cryoablation and cut-and-sew technique have been used for surgical ablation to treat atrial fibrillation. Ultrasonicscalpel is a surgical instrument used to simultaneously cut and cauterize tissue by ultrasound vibration. This device causes minimal lateral thermal tissue damage and increases the tissue penetration depth linearly with time. These features are suitable for surgical ablation for atrial fibrillation. This study evaluated surgical ablation with ultrasonic scalpel for atrial fibrillation.

Methods

From October 2017 to February 2019, 46 patients (mean age: 71.8 years [46–86], 28 male) with mitral valve procedure underwent surgical ablation using ultrasonic scalpel for atrial fibrillation. The ablation lines were carried out with Cox maze procedure or pulmonary vein isolation (PVI) on cardiopulmonary bypass. Endocardial atrial wall was ablated by direct touch with blade in a few seconds at energy level 5. Pathological study of left atrial wall received ablation with ultrasonic scalpel was carried out.

Results

Type of preoperative atrial fibrillation was persistent in 33 and paroxysmal in 13 patients. Mean left atrial diameter was 49.0 mm (35–81). Surgical ablation using ultrasonic scalpel was carried out to left atrium only or PVI in 33 patients and both atria in 13 patients. Mean surgical ablation time was 4 minutes and 21 seconds. Mitral valve repair and replacement were performed in 33 and replacement in 13 patients, respectively. Simultaneous surgery included 43 tricuspid valve repairs, 11 aortic valve replacements, and 7 coronary artery bypass grafting. Cardiopulmonary bypass and aortic cross-clamp times were 142.6 (70–261) and 98.6 (47–202) minutes, respectively. No operative death or perioperative stroke were observed. Thirty-eight patients (82.6%) returned to sinus rhythm immediately after surgery. Sinus rhythm was maintained in 30 patients (65.2%) in the mid-term period with average 142.2 days after surgery (7–426 days). Pathological study showed the atrial walls were not ablated transmurally. No complications including bleeding and tissue injury were observed.

Conclusion

Surgical ablation with ultrasonic scalpel for atrial fibrillation was feasible and provided satisfactory outcomes immediately after surgery and at mid-term. This technique can be performed in a short time without complications. Interestingly, pathological study showed no transmural tissue ablation despite of successful outcomes. This may imply transmural ablation is not necessarily mandatory for surgical ablation. Long-term follow-up are required to evaluate this technique.