Background: Brugada syndrome is a potential cause of sudden cardiac death (SCD) and is characterized by a distinct ECG, but not all patients with A Brugada ECG develop SCD. In this study we sought to examine if an artificial intelligence (AI) model can predict a previous or future ventricular fibrillation (VF) episode from a Brugada ECG.

Methods and Results: We developed an AI-enabled algorithm using a convolutional neural network. From 157 patients with suspected Brugada syndrome, 2,053 ECGs were obtained, and the dataset was divided into 5 datasets for cross-validation. In the ECG-based evaluation, the precision, recall, and F₁score were 0.79±0.09, 0.73±0.09, and 0.75±0.09, respectively. The average area under the receiver-operating characteristic curve (AUROC) was 0.81±0.09. On per-patient evaluation, the AUROC was 0.80±0.07. This model predicted the presence of VF with a precision of 0.93±0.02, recall of 0.77±0.14, and F₁score of 0.81±0.11. The negative predictive value was 0.94±0.11 while its positive predictive value was 0.44±0.29.

Conclusions: This proof-of-concept study showed that an AI-enabled algorithm can predict the presence of VF with a substantial performance. It implies that the AI model may detect a subtle ECG change that is undetectable by humans.

Background: Recently, the function of high-density lipoprotein (HDL), rather than the HDL cholesterol (HDL-C) level, has been attracting more attention in risk prediction for coronary artery disease (CAD).

Methods and Results: Patients with clinically diagnosed familial hypercholesterolemia (FH; n=108; male/female, 51/57) were assessed cross-sectionally. Serum cholesterol uptake capacity (CUC) levels were determined using our original cell-free assay. Linear regression was used to determine associations between CUC and clinical variables, including low-density lipoprotein cholesterol and the carotid plaque score. Multivariable logistic regression analysis was used to test factors associated with the presence of CAD. Among the 108 FH patients, 30 had CAD. CUC levels were significantly lower among patients with than without CAD (median [interquartile range] 119 [92–139] vs. 142 [121–165] arbitrary units [AU]; P=0.0004). In addition, CUC was significantly lower in patients with Achilles tendon thickness ≥9.0 mm than in those without Achilles tendon thickening (133 [110–157] vs. 142 [123–174] AU; P=0.047). Serum CUC levels were negatively correlated with the carotid plaque score (Spearman’s r=0.37; P=0.00018). Serum CUC levels were significantly associated with CAD, after adjusting for other clinical variables (odds ratio=0.86, 95% CI=0.76–0.96, P=0.033), whereas HDL-C was not.

Conclusions: HDL function, assessed by serum CUC level, rather than HDL-C level, adds risk stratification information among FH patients.

Background: Acute aortic dissection (AAD) is a life-threatening cardiovascular disease, with a reported incidence rate ranging from 2.5 to 7.2 per 100,000 person-years in several population-based registries in Western countries, but epidemiological data are lacking in Japan.

Methods and Results: The Shiga Stroke and Heart Attack Registry is an ongoing multicenter population-based registry of cerebro-cardiovascular diseases. We enrolled patients who developed AAD, defined by any imaging examination method from 2014 to 2015 in Shiga Prefecture. Death certificates were used to identify cases that were not registered at acute care hospitals. The incidence rates of AAD were calculated by age categories and adjusted using standard populations for comparison. We evaluated differences in patient characteristics between Stanford type A-AAD and type B-AAD subtypes. A total of 402 incident cases with AAD were analyzed. The age-adjusted incidence rates using the 2015 Japanese population and the 2013 European Standard Population were 15.8 and 12.2 per 100,000 person-years, respectively. Compared with cases of type B-AAD, those with type A-AAD were older (75.0 vs. 69.9 years, P=0.001) and more likely to be women (62.3% vs. 28.6%, P<0.001).

Conclusions: Population-based incidence rates of AAD in Japan appear to be higher than in previous reports from Western countries. Incident cases with type A-AAD were older and female predominance.

Background: To predict mortality in patients with acute heart failure (AHF), we created and validated an internal clinical risk score, the KICKOFF score, which takes physical and social aspects, in addition to clinical aspects, into account. In this study, we validated the prediction model externally in a different geographic area.

Methods and Results: There were 2 prospective multicenter cohorts (1,117 patients in Osaka Prefecture [KICKOFF registry]; 737 patients in Kochi Prefecture [Kochi YOSACOI study]) that had complete datasets for calculation of the KICKOFF score, which was developed by machine learning incorporating physical and social factors. The outcome measure was all-cause death over a 2-year period. Patients were separated into 3 groups: low risk (scores 0–6), moderate risk (scores 7–11), and high risk (scores 12–19). Kaplan-Meier curves clearly showed the score’s propensity to predict all-cause death, which rose independently in higher-risk groups (P<0.001) in both cohorts. After 2 years, the cumulative incidence of all-cause death was similar in the KICKOFF registry and Kochi YOSACOI study for the low-risk (4.4% vs. 5.3%, respectively), moderate-risk (25.3% vs. 22.3%, respectively), and high-risk (68.1% vs. 58.5%, respectively) groups.

Conclusions: The unique prediction score may be used in different geographic areas in Japan. The score may help doctors estimate the risk of AHF mortality, and provide information for decisions regarding heart failure treatment.

Background: Idiopathic bradyarrhythmia is considered to be due to pathological degeneration of the cardiac conduction system (CCS) during aging. There appears to have been no comprehensive genetic investigations in patients with idiopathic bradyarrhythmia.

Methods and Results: Ten autopsy cases with advanced bradyarrhythmia (6 men and 4 women; age: 70–94 years, 81.5±6.9 years; 5 cases each of sinus node dysfunction [SND] and complete atrioventricular block [CAVB]) were genetically investigated by using whole-exome sequencing. Morphometric analysis of the CCS was performed with sex-, age- and comorbidity-matched control cases. As a result, severe loss of nodal cells and distal atrioventricular conduction system were found in SND and CAVB, respectively. However, the conduction tissue loss was not significant in either the atrioventricular node or the proximal bundle of His in CAVB cases. A total of 13 heterozygous potential variants were found in 3 CAVB and 2 SND cases. Of these 13 variants, 4 were missense in the known progressive cardiac conduction disease-related genes: GATA4 and RYR2. In the remaining 9 variants, 5 were loss-of-function mutation with highly possible pathogenicity.

Conclusions: In addition to degenerative changes of selectively vulnerable areas in the heart during advancing age, the vulnerability of the CCS, which may be associated with “rare variants of small effect,” may also be a contributing factor to the degeneration of CCS, leading to “idiopathic” bradyarrhythmia.

Background: Low-invasive stereotactic body radiation therapy is a novel anti-arrhythmic strategy. The mechanisms underlying its effects against ventricular tachycardia/fibrillation (VT/VF) are gradually becoming clear, whereas those underlying atrial tachycardia/fibrillation (AT/AF) remain unknown. This study investigated the effects of carbon ion beam on gap junction expression and sympathetic innervation.

Methods and Results: Atrial and ventricular tachyarrhythmia models was established in 26 hypercholesterolemic (HC) 3-year-old New Zealand white rabbits; 12 rabbits were irradiated with a single 15-Gy carbon ion beam (targeted heavy ion irradiation [THIR]) and 14 were not (HC group). Eight 3-month-old rabbits (Young) were used as a reference group. In vivo induction frequencies in the Young, HC, and HC+THIR groups were 0%, 9.9%, and 1.2%, respectively, for AT/AF and 0%, 7.8%, and 1.2%, respectively, for VT/VF (P<0.01). The conduction velocity of the atria and ventricles on optical mapping was significantly reduced in the HC group; this was reversed in the HC+THIR group. Connexin-40 immunolabelling in the atria was 66.1–78.7% lower in the HC than Young group; this downregulation was less pronounced in the HC+THIR group (by 23.1–44.4%; P<0.01). Similar results were obtained for ventricular connexin-43. Sympathetic nerve densities in the atria and ventricles increased by 41.9–65.3% in the HC vs. Young group; this increase was reversed in the HC+THIR group.

Conclusions: Heavy ion radiation reduced vulnerability to AT/AF and VT/VF in HC elderly rabbits and improved cardiac conductivity. The results suggest involvement of connexin-40/43 upregulation and suppression of sympathetic nerve sprouting.

Background: Fluoroquinolone use can be associated with an increased risk of aortic aneurysm (AA) or aortic dissection (AD). The US Food and Drug Administration recently warned against fluoroquinolone use for high-risk patients, such as those with Marfan syndrome. However, the association between fluoroquinolone use and AA/AD risk was unknown in these high-risk patients and therefore it was studied in this work.

Methods and Results: Data were collected from a national database between 2000 and 2017 for 550 patients with AA/AD and any congenital aortic disease (mean age 41.5 years; 415 with Marfan syndrome). A case cross-over study was conducted to compare the risk of aortic events (AA/AD) associated with fluoroquinolone and amoxicillin use between the hazard period (from −60 days to −1 day) and a randomly selected reference period (−180 to −121 days; −240 to −181 days; and –300 to –241 days). Compared to the reference period without fluoroquinolone use, fluoroquinolone use during the hazard period was not associated with a greater risk of AA/AD (1.09% vs. 1.09%; odds ratio [OR] 1.000; 95% confidence interval [CI] 0.32–3.10), AA (OR 0.67; 95% CI 0.11–3.99), or AD (OR 1.33; 95% CI 0.30–5.96) in patients with congenital aortic disease or Marfan syndrome. This lack of association was maintained in subgroup analysis, including Marfan syndrome or not, age (≤50 vs. >50 years) and sex.

Conclusions: Fluoroquinolone use was not associated with an increased risk of AA/AD in patients with congenital aortic disease, including Marfan syndrome. More evidence is required for a fluoroquinolone pharmacovigilance plan in these patients.

Background: Tobacco smoking is a leading preventable cause of morbidity and mortality worldwide; still, the success rate of smoking cessation is low in general. From the viewpoint of public health and clinical care, an objective biomarker of long-term smoking behavior is sought.

Methods and Results: This study assessed DNA methylation as a biomarker of smoking in a hospital setting through a combination of molecular approaches including genetic, DNA methylation and mRNA expression analyses. First, in an epigenome-wide association study involving Japanese individuals with chronic cardiovascular disease (n=94), genome-wide significant smoking association was identified at 2 CpG sites on chromosome 5, with the strongest signal at cg05575921 located in intron 3 of the aryl-hydrocarbon receptor repressor (AHRR) gene. Highly significant (P<1×10⁻²⁷) smoking–cg05575921 association was validated in 2 additional panels (n=339 and n=300). For the relationship of cg05575921 methylation extent with time after smoking cessation and cumulative cigarette consumption among former smokers, smoking-related hypomethylation was found to remain for ≥20 years after smoking cessation and to be affected by multiple factors, such as cis-interaction of genetic variation. There was a significant inverse correlation (P=0.0005) between cg05575921 methylation extent and AHRR mRNA expression.

Conclusions: The present study results support that reversion of AHRR hypomethylation can be a quantifiable biomarker for progress in and observance of smoking cessation, although some methodological points need to be considered.

Background: It is still unclear whether changes in right ventricular function are associated with prognosis in heart failure (HF) patients. This study aimed to examine the prognostic effect of changes in right ventricular fractional area change (RVFAC).

Methods and Results: This study enrolled 480 hospitalized patients with decompensated HF, and measured RVFAC with echocardiography at discharge (first examination) and post-discharge in the outpatient setting (second examination). RVFAC was divided into 3 categories: >35% in 314 patients, 25–35% in 108 patients, and <25% in 58 patients. Next, based on changes in RVFAC from the first to the second examination, the patients were further classed into 4 groups: (1) Preserved/Unchanged (preserved and unchanged RVFAC, n=235); (2) Reduced/Improved (improved RVFAC in at least 1 category, n=106); (3) Reduced/Unchanged (reduced and unchanged RVFAC, n=47); and (4) Preserved or Reduced/Worsened (deteriorated RVAFC in at least 1 category, n=92). Multivariate logistic regression analysis revealed that chronic kidney disease and anemia were the predictors of the preserved or reduced/worsened RVFAC. In the Kaplan-Meier analysis, changes in RVFAC were associated with the cardiac event rate and all-cause mortality. In the multivariable Cox proportional hazard analysis, the preserved or reduced/worsened RVFAC was an independent predictor of cardiac events and all-cause mortality.

Conclusions: Changes in RVFAC were associated with post-discharge prognosis in hospitalized heart failure patients.

Background: Dilated cardiomyopathy (DCM) associated with inflammation is diagnosed by endomyocardial biopsy; patients with this have a poorer prognosis than patients without inflammation. To date, standard diagnostic criteria have not been established.

Methods and Results: This study analyzed clinical records and endomyocardial biopsy samples of 261 patients with DCM (201 males, median left ventricular ejection fraction; 28%) from 8 institutions in a multicenter retrospective study. Based on the European Society of Cardiology criteria and CD3 (T-lymphocytes) and CD68 (macrophages) immunohistochemistry, 48% of patients were categorized as having inflammatory DCM. For risk-stratification, we divided patients into 3 groups using Akaike Information Criterion/log-rank tests, which can determine multiple cut-off points: CD3⁺-Low, <13/mm²(n=178, 68%); CD3⁺-Moderate, 13–24/mm²(n=58, 22%); and CD3⁺-High, ≥24/mm²(n=25, 10%). The survival curves for cardiac death or left ventricular assist device implantation differed significantly among the 3 groups (10-year survival rates: CD3⁺-Low: 83.4%; CD3⁺-Moderate: 68.4%; CD3⁺-High: 21.1%; Log-rank P<0.001). Multivariate Cox analysis revealed CD3⁺count as a potent independent predictive factor for survival (fully adjusted hazard ratio: CD3⁺-High: 5.70, P<0.001; CD3⁺-Moderate: 2.64, P<0.01). CD3⁺-High was also associated with poor left ventricular functional and morphological recovery at short-term follow up.

Conclusions: Myocardial CD3⁺T-lymphocyte infiltration has a significant prognostic impact in DCM and a 3-tiered risk-stratification model could be helpful to refine patient categorization.

Background:The clinical significance of concomitant mitral regurgitation (MR) has not been well addressed in patients with severe aortic stenosis (AS).

Methods and Results:We analyzed 3,815 patients from a retrospective multicenter registry of severe AS in Japan (CURRENT AS registry). We compared the clinical outcomes between patients with moderate/severe MR and with none/mild MR according to the initial treatment strategy (initial aortic valve replacement [AVR] or conservative strategy). The primary outcome measure was a composite of aortic valve-related death or heart failure hospitalization. At baseline, moderate/severe MR was present in 227/1,197 (19%) patients with initial AVR strategy and in 536/2,618 (20%) patients with a conservative strategy. The crude cumulative 5-year incidence of the primary outcome measure was significantly higher in patients with moderate/severe MR than in those with none/mild MR, regardless of the initial treatment strategy (25.2% vs. 14.4%, P<0.001 in the initial AVR strategy, and 63.3% vs. 40.7%, P<0.001 in the conservative strategy). After adjusting confounders, moderate/severe MR was not independently associated with higher risk for the primary outcome measure in the initial AVR strategy (hazard ratio [HR] 1.11, 95% confidence interval [CI] 0.67–1.83, P=0.69), and in the conservative strategy (HR 1.13, 95% CI 0.93–1.37, P=0.22).

Conclusions:Concomitant moderate/severe MR was not independently associated with higher risk for the primary outcome measure regardless of the initial treatment strategy.

Background:There is a gradual progression from paroxysmal to persistent atrial fibrillation (AF) in humans. To elucidate the mechanism involved, the creation of an artificial atrial substrate to persist AF in mice was attempted.

Methods and Results:This study used wild type (WT) mice, but it is difficult to induce AF in them. A novel antegrade perfusion method from the left ventricle (LV) to enlarge both atria for artificial atrial modification was proposed in this study. Short duration AF was induced by burst pacing under this method. Optical mapping analysis revealed non-sustained focal type and meandering spiral reentrants after short duration AF. A tiny artificial substrate (~1.2 mm in diameter) was added in by laser irradiation to create a critical atrial arrhythmogenic substrate. Burst pacing was performed in a non-laser group (n=8), a circular-shape laser group (n=8), and a wedge-shaped dent laser group (n=8). We defined AF and atrial tachycardia (AT) as atrial arrhythmia (AA). Long-lasting AA was defined as lasting for ≥30 min. Long-lasting AA was observed in 0/8, 0/8, and 6/8 (75%) mice in each group. Optical mapping analysis revealed that the mechanism was AT with a stationary rotor around the irradiated margin.

Conclusions:Regrettably, this study failed to reproduce persistent AF, but succeeded in creating an arrhythmic substrate that causes sustained AT in WT mice.

Background: Elevated central venous pressure (CVP) in heart failure causes renal congestion, which deteriorates prognosis. Sodium glucose co-transporter 2 inhibitor (SGLT2-i) improves kidney function and heart failure prognosis; however, it is unknown whether they affect renal congestion. This study investigated the effect of SGLT2-i on the kidney and left ventricle using model rats with hypertensive heart failure.

Methods and Results: Eight rats were fed a 0.3% low-salt diet (n=7), and 24 rats were fed an 8% high-salt diet, and they were divided into 3 groups of untreated (n=6), SGLT2-i (canagliflozin; n=6), and loop diuretic (furosemide; n=5) groups after 11 weeks of age. At 18 weeks of age, CVP and renal intramedullary pressure (RMP) were monitored directly by catheterization. We performed contrast-enhanced ultrasonography to evaluate intrarenal perfusion. In all high-salt fed groups, systolic blood pressure was elevated (P=0.287). The left ventricular ejection fraction did not differ among high-salt groups. Although CVP decreased in both the furosemide (P=0.032) and the canagliflozin groups (P=0.030), RMP reduction (P=0.003) and preserved renal medulla perfusion were only observed in the canagliflozin group (P=0.001). Histological analysis showed less cast formation in the intrarenal tubule (P=0.032), left ventricle fibrosis (P<0.001), and myocyte thickness (P<0.001) in the canagliflozin group than in the control group.

Conclusions: These results suggest that SGLT2-i causes renal decongestion and prevents left ventricular hypertrophy, fibrosis, and dysfunction

Background: Differences in the impact of the 1- or 2-stent strategy in similar coronary bifurcation lesion conditions are not well understood. This study investigated the clinical outcomes and its predictors between 1 or 2 stents in propensity score-matched (PSM) complex bifurcation lesions.

Methods and Results: We analyzed the data of patients with bifurcation lesions, obtained from a multicenter registry of 2,648 patients (median follow up, 53 months). The patients were treated by second generation drug-eluting stents (DESs). The primary outcome was target lesion failure (TLF), composite of cardiac death, target vessel myocardial infarction (TVMI), and ischemia-driven target lesion revascularization (TLR). PSM was performed to balance baseline clinical and angiographic discrepancies between 1 and 2 stents. After PSM (N=333 from each group), the 2-stent group had more TLRs (hazard ratio [HR] 3.14, 95% confidence interval [CI] 1.42–6.97, P=0.005) and fewer hard endpoints (composite of cardiac death and TVMI; HR 0.44, 95% CI 0.19–1.01, P=0.054), which resulted in a similar TLF rate (HR 1.40, 95% CI 0.83–2.37, P=0.209) compared to the 1-stent group. Compared with 1-stent, the 2-stent technique was more frequently associated with less TLF in the presence of main vessel (p_interaction=0.008) and side branch calcification (p_interaction=0.010).

Conclusions: The 2-stent strategy should be considered to reduce hard clinical endpoints in complex bifurcation lesions, particularly those with calcifications.

Background:A thorough understanding of the anatomy of the aortic valve is necessary for aortic valve-sparing surgery. Normal valvar dimensions and their relationships in the living heart, however, have yet to be fully investigated in a 3-dimensional fashion.

Methods and Results:In total, 123 consecutive patients (66±12 years, Men 63%) who underwent coronary computed tomographic angiography were enrolled. Mid-diastolic morphology of the aortic roots, including height of the interleaflet triangles, geometric height, free margin length of each leaflet, effective height, and coaptation length were measured using multiplanar reconstruction images. Average height of the interleaflet triangle, geometric height, free margin length, effective height, and the coaptation length were 17.3±1.8, 14.7±1.3, 32.6±3.6, 8.6±1.4, and 3.2±0.8 mm, respectively. The right coronary aortic leaflet displayed the longest free margin length and shortest geometric height. Geometric height, free margin length, and effective height showed positive correlations with aortic root dimensions. Coaptation length, however, remained constant regardless of aortic root dimensions.

Conclusions:Diversities, as well as characteristic relationships among each value involving the aortic root, were identified using living-heart datasets. The aortic leaflets demonstrated compensatory elongation along with aortic root dilatation to maintain constant coaptation length. These measurements will serve as the standard value for revealing the underlying mechanism of aortic regurgitation to plan optimal aortic valve-sparing surgery.

Background:The aim of this study was to clarify the clinical outcomes of patients with atrial functional mitral regurgitation (FMR) who underwent the MitraClip procedure compared with those with conventional FMR and sinus rhythm (SR).

Methods and Results:Of 303 patients with FMR who underwent the MitraClip procedure, 40 with “atrial-FMR” defined as FMR with permanent atrial fibrillation and normal left ventricular (LV) function/size and 115 with “sinus-FMR” defined as FMR with SR and LV dysfunction were reviewed. Transthoracic and 3D transesophageal echocardiography, and the cardiac complication rate (composite of all-cause death, heart failure admission, mitral valve (MV) surgery, and redo MitraClip procedure) during the 12-month follow-up were compared between the groups. After the MitraClip procedure, reductions in the mitral annular area and its anteroposterior dimension and in the leaflet closure area were observed in both groups. MV orifice area was smaller with greater transmitral pressure gradient (P<0.05) after the procedure in atrial-FMR patients than in those with sinus-FMR. The prevalence of residual MR was similar, but significant tricuspid regurgitation (TR) was more prevalent in the atrial-FMR group at follow-up. Cardiac complication rate was comparable between groups (20% vs. 25%, P=0.63).

Conclusions:Reduction of MR occurred in atrial-FMR probably because of the increase in leaflet coaptation area. Significant TR was more common after the MitraClip procedure in patients with atrial-FMR than with sinus-FMR. However, mid-term outcomes were comparable between patients with atrial-FMR and sinus-FMR.

Background:Diagnosis of heart failure with preserved ejection fraction (HFpEF) remains challenging in elderly. This study investigated the diagnostic ability of the HFA-PEFF scoring system in elderly patients (>75 years of age).

Methods and Results:This study enrolled 286 subjects aged >75 years (130 men; mean [± SD] age 81.5±5.1 years): 95 healthy controls, 98 with hypertension (HT), and 93 with HFpEF. The HFA-PEFF score was calculated as a sum of points in functional, morphological, and biomarker domains. In the HFpEF group, 84%, 84%, and 70% of subjects met the major functional, morphological, and biomarker criteria for HFpEF, respectively. Thus, 73 subjects with HFpEF (78%) were diagnosed as having HFpEF using the HFA-PEFF scoring system. In contrast, among the healthy controls and subjects with HT, 52% and 72%, respectively, met the major functional criteria for HFpEF, 28% and 53%, respectively, met the morphological criteria, and 0% and 24%, respectively, met the biomarker criteria. As such, 32 subjects with HT (33%) were diagnosed with HFpEF. Even in the healthy control group, 72% were classified as having an intermediate probability of HFpEF, and 3 were diagnosed with HFpEF.

Conclusions:In the late elderly, the HFA-PEFF scoring system diagnosed subjects with HFpEF precisely. In addition, this scoring system may be able to detect early stage HFpEF in the subclinical population.

Background:The risk prediction of incident atrial fibrillation (AF) is useful to prevent AF and its complications. The aim of this study is to develop a new risk prediction model for incident AF using the prospective longitudinal data from a general Japanese population.

Methods and Results:A total of 2,442 community-dwelling AF-free residents aged ≥40 years were followed up from 1988 to 2012 (46,422 person-years). The development of AF was confirmed by a standard 12-lead electrocardiogram at repeated health examinations and by medical records at clinics or hospitals. The risk prediction model for incident AF was developed using a Cox proportional hazards model. During the follow up, 230 AF events were confirmed. Age, sex, systolic blood pressure, waist circumference, estimated glomerular filtration rate, abnormal cardiac murmur, high R-wave amplitude, and arrhythmia other than AF were selected for inclusion in the model. This model showed good discrimination (Harrell’s c statistics: 0.785) and calibration (Greenwood-Nam-D’Agostino test: P=0.87) for AF risk at 10 years.

Conclusions:The new risk prediction model showed good performance on the individual risk assessment of the future onset of AF in a general Japanese population. As this model included commonly used clinical parameters, it may be useful for determining the requirements for the careful evaluation of AF, such as frequent electrocardiogram examinations in clinical settings, and subsequent reductions in the risk of AF-related complications.

Background:Sirt7 is a recently identified sirtuin and has important roles in various pathological conditions, including cancer progression and metabolic disorders. It has previously been reported that Sirt7 is a key molecule in acute myocardial wound healing and pressure overload-induced cardiac hypertrophy. In this study, the role of Sirt7 in neointimal formation after vascular injury is investigated.

Methods and Results:Systemic (Sirt7^−/−) and smooth muscle cell-specific Sirt7-deficient mice were subjected to femoral artery wire injury. Primary vascular smooth muscle cells (VSMCs) were isolated from the aorta of wild type (WT) and Sirt7^−/−mice and their capacity for cell proliferation and migration was compared. Sirt7 expression was increased in vascular tissue at the sites of injury. Sirt7^−/−mice demonstrated significant reduction in neointimal formation compared to WT mice. In vitro, Sirt7 deficiency attenuated the proliferation of serum-induced VSMCs. Serum stimulation-induced upregulation of cyclins and cyclin-dependent-kinase 2 (CDK2) was significantly attenuated in VSMCs of Sirt7^−/−compared with WT mice. These changes were accompanied by enhanced expression of the microRNA 290-295 cluster, the translational negative regulator of CDK2, in VSMCs of Sirt7^−/−mice. It was confirmed that smooth muscle cell-specific Sirt7-deficient mice showed significant reduction in neointima compared with control mice.

Conclusions:Sirt7 deficiency attenuates neointimal formation after vascular injury. Given the predominant role in vascular neointimal formation, Sirt7 is a potentially suitable target for treatment of vascular diseases.

Background:Activated factor X (FXa), which contributes to chronic inflammation via protease-activated receptor 2 (PAR2), might play an important role in atrial fibrillation (AF) arrhythmogenesis. This study aimed to assess whether PAR2 signaling contributes to AF arrhythmogenesis and whether rivaroxaban ameliorates atrial inflammation and prevents AF.

Methods and Results:In Study 1, PAR2 deficient (PAR2−/−) and wild-type mice were infused with angiotensin II (Ang II) or a vehicle via an osmotic minipump for 2 weeks. In Study 2, spontaneously hypertensive rats (SHRs) were treated with rivaroxaban, warfarin, or vehicle for 2 weeks after 8 h of right atrial rapid pacing. The AF inducibility and atrial remodeling in both studies were examined. Ang II-treated PAR2−/− mice had a lower incidence of AF and less mRNA expression of collagen1 and collagen3 in the atrium compared to wild-type mice treated with Ang II. Rivaroxaban significantly reduced AF inducibility compared with warfarin or vehicle. In SHRs treated with a vehicle, rapid atrial pacing promoted gene expression of inflammatory and fibrosis-related biomarkers in the atrium. Rivaroxaban, but not warfarin, significantly reduced expression levels of these genes.

Conclusions:The FXa–PAR2 signaling pathway might contribute to AF arrhythmogenesis associated with atrial inflammation. A direct FXa inhibitor, rivaroxaban, could prevent atrial inflammation and reduce AF inducibility, probably by inhibiting the pro-inflammatory activation.