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Abstract Background The purpose of this study was to evaluate the prognostic value of atrial fibrillation (AF) in patients with acute coronary syndrome (ACS). Methods A total 648 of consecutive ACS patients were divided into non‐AF and all‐AF groups. The all‐AF group was further subdivided into new‐onset AF and pre‐existing AF groups. We compared prognosis among these groups using the Cox regression analysis. Results The mean follow‐up period was 1.4 ± 1.2 years. Overall patient numbers were 538 in non‐AF and 110 in all‐AF groups (67 in new‐onset AF and 43 in pre‐existing AF). Seventy‐eight all‐cause deaths and 42 cardiac deaths were observed. New‐onset AF had a worse prognosis than the other groups in the Kaplan‐Meier analysis (P = 0.025) after observation. Cox regression analysis indicated no significant difference for all‐cause death among the three groups. The hazard ratio of congestive heart failure requiring hospitalization was significantly higher in the all‐AF and new‐onset AF group than in the non‐AF group. Multivariate logistic regression analysis revealed that renal dysfunction, peripheral arterial disease, Killip classification ≥2, and left ventricular ejection fraction (LVEF) were independent predictors of all‐cause death. The new‐onset AF group had the highest prevalence of Killip classification ≥2 and the lowest LVEF. Conclusion In our study, AF was not an independent predictor of all‐cause death, but new‐onset AF may be associated with worse prognosis and future heart failure.

Background & purpose: We have conducted a retrospective observational study to analyze the correlation between the CHADS2 score, the modified CHA2DS2-VASc (mCHA2DS2-VASc) score, and the incidence of all-cause death and congestive heart failure (CHF). Methods: The study cohort consisted of 292 consecutive patients with nonvalvular atrial fibrillation (NVAF) admitted to our hospital from 2012 to 2014. Electronic medical records were used to confirm medical history including prior heart failure, hypertension, diabetes, stroke, and coronary disease. A follow-up survey for all-cause deaths and incidence of CHF was carried out from the baseline data to May 2015. We analyzed the correlation between each score and the endpoints using the Kaplan-Meier method and the Cox proportional hazards model. Result: During the follow up period (mean=1.6 years), 69 all-cause deaths and 58 CHF events occurred in the cohort. There was no significant association between these scores and all-cause death in our CHF cohort. The incidence of CHF significantly increased along with increased CHADS2 (p=0.018) or mCHA2DS2-VASc scores (p=0.044). The hazard ratio (HR) for CHF after adjustment for drug treatment was obtained from a Cox proportional hazards model. The HRs for the CHADS2 and mCHA2DS2-VASc scores were 1.38 (95% CI; 1.13–1.68) and 1.35 (95% CI; 1.24–1.59), respectively. Conclusion: Calculation of the CHADS2 and mCHA2DS2-VASc scores in order to evaluate the risk of systemic thromboembolism was useful to predict the onset of CHF, but not all-cause death, in patients with NVAF.

Background: The therapeutic goals of atrial fibrillation (AF) patients are to reduce symptoms and prevent severe complications associated with AF. This study compared the efficacy of flecainide versus pilsicainide in reducing the frequency of AF and improving quality of life (QOL) in symptomatic paroxysmal AF patients without structural heart disease. Methods: The Atrial Fibrillation and Quality Of Life (AF-QOL) study was a prospective, multicenter, randomized, open-label crossover study that compared flecainide and pilsicainide as antiarrhythmic drug therapy. Patients were randomized to receive 3 months of treatment with flecainide twice daily or pilsicainide 3 times daily. Each treatment consisted of a dose-finding phase (weeks 1–4) and an efficacy phase (weeks 5–12). Forty-three patients completed the trial. The main outcome was the number of days with documented AF episodes using a patient-operated electrocardiogram. QOL questionnaires (SF-36 and AF-specific QOL scores) were also completed. Results: The median (range) AF frequencies (days/8 weeks) were 2 (0–50) in the flecainide treatment group and 1 (0–54) in the pilsicainide treatment group (no significant between-group difference). No significant difference in the first recurrence of AF during the efficacy phase was noted between flecainide and pilsicainide treatments. The frequency and severity scores of AF-related symptoms improved from baseline to the end of the treatment periods. No significant differences in SF-36 or AF-related QOL scores were noted between the treatment groups. Conclusions: This study found no difference in AF frequency or QOL between symptomatic paroxysmal AF patients who received flecainide or pilsicainide.

We consider the discrete-time quantum walk whose local dynamics is denoted by a common unitary matrix C at the perturbed region {0,1,⋯,M−1} and free at the other positions. We obtain the stationary state with a bounded initial state. The initial state is set so that the perturbed region receives the inflow ωn at time n(|ω|=1). From this expression, we compute the scattering on the surface of −1 and M and also compute the quantity how quantum walker accumulates in the perturbed region; namely, the energy of the quantum walk, in the long time limit. The frequency of the initial state of the influence to the energy is symmetric on the unit circle in the complex plain. We find a discontinuity of the energy with respect to the frequency of the inflow.

Background: Approximately one-third of the patients undergoing cardiovascular surgery reportedly experience paroxysmal atrial fibrillation (AF) during the postoperative period. However, the usefulness of antiarrhythmic drugs for preventing postoperative AF recurrence in the Japanese population has not been extensively studied. Methods: From a total of 118 patients who developed postoperative paroxysmal AF between April 2009 and March 2011, 72 patients (45 men, mean age 68±8 years) requiring treatment for postoperative AF due to symptoms lasting ≥30 min were enrolled to prospectively investigate the efficacy of oral bepridil (100 mg/day, n=37) or aprindine (40 mg/day, n=35). Result: The AF recurrence-free survival rates at 1, 3, 7, and 14 days were 100%, 94%, 57%, and 49%, respectively, in the aprindine group, and 100%, 97%, 86%, and 76%, respectively, in the bepridil group (P=0.028, aprindine vs. bepridil). Conclusion: Bepridil, at a fixed dose of 100 mg/day, was considered to be more effective than a routine dose of aprindine for the prevention of postoperative AF recurrence.

Existence of the eigenvalues of the discrete-time quantum walks is deeply related to localization of the walks. We revealed, for the first time, the distributions of the eigenvalues given by the splitted generating function method (the SGF method) of the space-inhomogeneous quantum walks in one dimension we had treated in our previous studies. Especially, we clarified the characteristic parameter dependence for the distributions of the eigenvalues with the aid of numerical simulation.

Background: Dyspepsia (including upper abdominal pain, abdominal pain, abdominal discomfort, epigastric discomfort, and dyspepsia) is a symptom that is carefully monitored during dabigatran treatment. However, detailed information on dyspepsia, including onset, duration, severity, and use of drug treatment, has not yet been established in Japanese patients. Methods: We conducted a multi-center, prospective, open-label, randomized, and parallel-group-comparison observational study of 309 patients with non-valvular atrial fibrillation who had been newly prescribed dabigatran at 19 institutes in Japan. Gastrointestinal adverse events were evaluated using the Global Overall Severity (GOS) scale self-reports to describe symptoms and to assess frequency and severity of symptoms (Part 1). Thereafter, patients with a GOS score ≥3 were randomized to receive a 4-week course of a proton pump inhibitor, an H2-receptor antagonist or a gastric mucosal protective drug (Part 2). Results: The incidence of dyspepsia symptoms due to dabigatran was 17.2% (53/309, 95% confidence interval 13.1–21.8%), with 77% of events occurring within 10 days of initiation. Five patients discontinued the study because of dyspepsia. At the end of the observation period, the mean GOS score of those reporting dyspepsia was 3.5±1.7, with 11.3% (35/309) reporting a score ≥3. Substantial differences in the incidence of dyspepsia were observed between the study institutes (0–41%). In the multivariate regression analysis, no significant factor was found to affect incidence or severity of dyspepsia. The majority (83–100%) reported that symptoms improved with treatment (GOS score ≤2), and there was no significant difference between the three different treatment groups. Conclusions: The reported symptoms of dyspepsia were generally mild, but were moderate in approximately 10% of patients. Proton pump inhibitors, H2-receptor antagonists, and rebamipide seemed to be equally effective in relieving dabigatran-related dyspepsia (umin-CTR UMIN000007579).

Atrial fibrillation is now recognized as a significant medical and social problem. Atrial fibrillation not only causes cardiovascular complications, including thromboembolism and heart failure, but also decreases the survival of patients with impaired left ventricular function; thus, it is considered an independent factor for cardiovascular death. The goal of antiarrhythmic drug therapy for atrial fibrillation is improvement of daily quality of life and cardiovascular prognosis in maintaining sinus rhythm, while ensuring the safety of antiarrhythmic drugs. Antiarrhythmic drugs are prescribed to prevent recurrence of atrial fibrillation; however, they demonstrate limited efficacy. Recently, catheter ablation has been established as a promising new therapy to prevent recurrence of atrial fibrillation, even though this procedure would be difficult to apply clinically because of its complications and the large number of patients requiring treatment. Since the antiarrhythmic drugs remain the first-line, primary therapy for paroxysmal atrial fibrillation, clinicians should select appropriate antiarrhythmic drugs for treatment of paroxysmal atrial fibrillation based on individual patient characteristics. Herein, I review the current strategies of antiarrhythmic drug therapy for paroxysmal atrial fibrillation from the point of view of pharmacological prevention of atrial fibrillation recurrence, improvement of patient quality of life, and cardiovascular prognosis.

Aim and method: There have been few reports about the risk of ischemic stroke in elderly patients with non-valvular paroxysmal atrial fibrillation (NVPAF). The aim of this study was to evaluate the validity of the guidelines issued by the Japanese Circulation Society to prevent ischemic stroke for NVPAF in patients without a high risk of ischemic stroke. The risk evaluation was made based on the CHADS2 Score. However, we excluded age in this study, but included coronary disease. This study investigated a total of 150 patients with paroxysmal atrial fibrillation (AF) who did not have a high risk of stroke (117 men and 33 women, mean age 68 ± 12 years). The patients were divided into three groups according to age: the patients who were less than 60 years old (Group I, N = 58, Antithrombic therapy (+) = 18), those who were between 60 and 75 years old (Group II, N = 68, Antithrombic therapy (+) = 36) and those who were more than 75 years old (Group III, N = 24, Antithrombic therapy (+) = 7). The annual rates of thromboembolism among three groups were retrospectively analyzed. The mean follow-up periods were 56 ± 37 months. Results: (1) The annual rate of thromboembolism in Group III (4.0%) was significantly higher than in Group I (1.4%) and Group II (1.8%) (P < 0:05). (2) The annual rates of thromboembolism in patients without antithrombotic therapy were 2.1% in Group I, 1.3% in Group II and 3.9% in Group III. The annual rate was significantly lower in Group II than in Group III (P < 0:05). (3) The annual rates of thromboembolism with aspirin treatment (80- 100 mg/day) were 0% in Group I, 3.0% in Group II and 8.4% in Group III. There was a significant difference in the annual rate among the three groups (P < 0:05). (4) The annual rate of thromboembolism in patients with warfarin treatment was 0% in Group I, 1.5% in Group II and 0% in Group III (P = NS among 3 groups). Conclusion: Antithrombic therapy is required in elderly patients with NVPAF to prevent ischemic stroke. Antithrombic therapy with Warfarin, but not aspirin, reduces ischemic stroke in patients with NVPAF regardless of their age.

Objective: To investigate the long-term effects of combination therapy with antiarrhythmic agents and pravastatin (10 mg/day) in maintaining sinus rhythm in patients with paroxysmal atrial fibrillation (AF) and hyperlipidemia. Method and Results: In all, 318 patients (mean age: 69 ± 12 years) with paroxysmal AF were divided into 2 groups, one receiving pravastatin for hyperlipidemia (pravastatin (+) group, N = 41) and the other not (pravastatin (−) group, N = 277). At 60 months, the survival rate for patients free from conversion to permanent AF was significantly greater in the pravastatin (+) group than in the pravastatin (−) group. The percentage of patients who eventually developed permanent AF despite anti-arrhythmic therapy was significantly lower in the pravastatin (+) group than in the pravastatin (−) group (9.8% vs. 25.3%). Left atrial dimensions were significantly increased in the pravastatin (−) group during the follow-up period (from 34.8 ± 6.6 mm to 37.6 ± 7.0 mm: p < 0.01). In contrast, in the pravastatin (+) group, left atrial dimensions remained unchanged between baseline and after treatment (34.4 ± 7.3 mm vs 35.5 ± 6.6 mm). Conclusion: In patients with paroxysmal AF and hyperlipidemia, addition of pravastatin to anti-arrhythmic agents seems to enhance the efficacy of these agents in maintaining sinus rhythm and preventing the development of structural remodeling in the myocardium.

Myrmecophilus crickets (Myrmecophilidae, Orthoptera) are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. We focused on two of these species, M. kinomurai and M. kubotai, and compared their host and habitat use. Previous work based on a limited sampling effort suggested that these two species share some ant species as hosts, but that their habitat (open versus shaded) preferences differ. Here, on the basis of exhaustive sampling across Japan, we confirmed that M. kinomurai and M. kubotai do not differ in their host ant preferences: both prefer formicine ants as hosts. As for habitat preferences, M. kubotai occurred significantly more often in open habitats than in shaded ones (P < 0.05). In contrast, M. kinomurai showed no habitat preference in areas where M. kubotai did not occur. However, M. kinomurai showed an obvious preference for shaded environments in areas of sympatry with its potential competitor M. kubotai. This pattern suggests that interspecific competition between M. kinomurai and M. Kubotai is a factor causing habitat differentiation in areas of sympatry.

This study sought to evaluate the efficacy of long-term flecainide therapy in maintaining sinus rhythms in patients with paroxysmal atrial fibrillation (AF. based on time of onset. Flecainide (150 mg/day. was administered as an antiarrhythmic drug to a total of 70 patients (54 men and 16 women: mean age 65 ± 10 years. after sinus rhythm was restored spontaneously or by electrical and/or pharmacological cardioversion. Paroxysmal AF was divided into three categories based on time of onset: diurnal type (N = 11), nocturnal type (N = 13), and mixed type (N = 46). The mean follow-up period was 37.7 ± 17.7 months. The duration of sinus rhythm maintenance in patients with diurnal and nocturnal paroxysmal AF was 32.4 ± 10.4 months and 20.8 ± 8.3 months, respectively; the duration of sinus rhythm maintenance in those with mixed paroxysmal AF was only 7.2 ± 2.1 months. Significant differences were observed in duration between diurnal and mixed cases (mean ± S.E., P < 0.05). Actuarial recurrence-free rates at 1, 3, 6, 9 and 12 months were 90.9%, 63.6%, 63.6%, 54.5%, and 54.5%, respectively, for diurnal cases; 84.6%, 76.9%, 53.8%, 38.5%, and 30.8%, respectively, for nocturnal cases; and 58.7%, 39.1%, 28.3%, 21.7%, and 15.2% respectively, for mixed cases. Significant differences in rates at 12 months were observed between diurnal and mixed cases (P < 0.05). These results suggest that flecainide is highly effective in preventing AF recurrence in patients with diurnal paroxysmal AF.

A previously reported mitochondrial DNA (mtDNA) phylogeny of Crematogaster (subgenus Decacrema) ants inhabiting Macaranga myrmecophytes indicated that the partners diversified synchronously and their specific association has been maintained for 20 million years. However, the mtDNA clades did not exactly match morphological species, probably owing to introgressive hybridization among younger species. In this study, we determined the congruence between nuclear simple sequence repeat (SSR, also called microsatellite) genotyping and mtDNA phylogeny to confirm the suitability of the mtDNA phylogeny for inferring the evolutionary history of Decacrema ants. Analyses of ant samples from Lambir Hills National park, northeastern Borneo, showed overall congruence between the SSR and mtDNA groupings, indicating that mtDNA markers are useful for delimiting species, at least at the local level. We also found overall high host-plant specificity of the SSR genotypes of Decacrema ants, consistent with the specificity based on the mtDNA phylogeny. Further, we detected cryptic genetic assemblages exhibiting high specificity toward particular plant species within a single mtDNA clade. This finding, which may be evidence for rapid ecological and genetic differentiation following a host shift, is a new insight into the previously suggested long-term codiversification of Decacrema ants and Macaranga plants.

OBJECTIVES: Atrial fibrillation (AF) is a significant public health issue due to its high prevalence in the general population, and is associated with an increased risk of cardiovascular (CV) events including systemic thrombo-embolism, heart failure, and coronary artery disease. The relationship between plasma B-type natriuretic peptide (BNP) and CV risk in real world AF subjects remains unknown. METHODS: The subject of the study (n = 228; mean age = 69 years) was unselected individuals with AF in a community-based population (n = 15,394; AF prevalence rate = 1.5%). The CV event free rate within each BNP tertile was estimated, and Cox regression analysis was performed to examine the relative risk of the onset of CV events among the tertiles. The prognostic ability of BNP was compared to an established risk score for embolic events (CHADS2 score). In addition, to determine the usefulness of BNP as a predictor in addition to CHADS2 score, we calculated Net Reclassification Improvement (NRI) and Integrated Discrimination Improvement (IDI) indices. RESULTS: During the follow-up period 58 subjects experienced CV events (52 per 1,000 person-years). The event-free ratio was significantly lower in the highest tertile (p < 0.02). After adjustment for established CV risk factors, the hazard ratio (HR) of the highest tertile was significantly higher than that of the lowest tertile (HR = 2.38; p < 0.02). The predictive abilities of plasma BNP in terms of sensitivity and specificity for general CV events were comparable to those of CHADS2 score. Adding BNP to the CHADS2 score only model improved the NRI (0.319; p < 0.05) and the IDI (0.046; p < 0.05). CONCLUSION: Plasma BNP is a valuable biomarker both singly or in combination with an established scoring system for assessing general CV risk including stroke, heart failure and acute coronary syndrome in real-world AF subjects.

Myrmecophilus ant crickets (Orthoptera: Myrmecophilidae) are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. Some of these species have restricted host ranges and behave intimately toward their host ant species (i.e., they are host specialist). We focused on one species, M. tetramorii, which uses the myrmicine ant Tetramorium tsushimae as its main host. All but one M. tetramorii individuals were collected specifically from nests of T. tsushimae in the field. However, behavioral observation showed that all individuals used in the experiment received hostile reactions from the host ants. There were no signs of intimate behaviors such as grooming of hosts or receipt of mouth-to-mouth feeding from hosts, which are seen in some host-specialist Myrmecophilus species among obligate host-ant species. Therefore, it may be that M. tetramorii is the species that is specialized to exploit the host by means other than chemical integration.