Effects of aspirin and trapidil on cardiovascular events after acute myocardial infarction. Japanese Antiplatelets Myocardial Infarction Study (JAMIS) Investigators

Long-Term Prognosis of Patients with Myocardial Infarction Type 1 and Type 2 with and without Involvement of Coronary Vasospasm

While prognoses in relation to myocardial infarction (MI) type have been elucidated in past reports, the results were not consistent, perhaps due to occurrence of Type 2 MI with CVS and its mortality. The Japanese registry of acute Myocardial Infarction diagnosed by Universal Definition (J-MINUET) is a prospective multicenter registry in Japan. In contrast to thromboembolic event-related Type 1 myocardial infarction (MI), clinical features of Type 2 MI, including coronary vasospasm (CVS), are varied due to the heterogeneous nature of its development. To elucidate the MI type-related all-cause mortality, 2989 consecutive patients with AMI were stratified as Type 1 MI, Type 2 MI with CVS, and Type 2 MI with non-CVS. Most patients (n = 2834; 94.8%) were classified as Type 1 MI and 155 patients (5.2%) were classified as Type 2 MI. Of the Type 2 MI patients, 87 (56% of Type 2 MI) were diagnosed as MI with CVS. Although the 3-year mortality was comparable between Type 1 and Type 2 MI patients, significant differences were observed between Type 2 MI with CVS and with non-CVS (3.4% and 22.1%, p < 0.001). Among Japanese patients with AMI, mortality rates between Type 1 MI and Type 2 MI are comparable, but further stratification of Type 2 MI (with or without CVS) may be useful in predicting the prognosis of patients with Type 2 MI.

The safety of upper gastrointestinal endoscopic biopsy in patients receiving antithrombic drugs. A single-centre prospective observational study

Introduction

In July 2012, the Japan Gastroenterological Endoscopy Society updated their guidelines on gastroenterological endoscopy in patients undergoing antithrombotic therapy, although the safety of endoscopic procedures in patients receiving antithrombotic drugs has yet to be sufficiently studied.

Aim

This study evaluates the safety of upper gastroenterological endoscopic biopsy in patients receiving antithrombotic drugs. We evaluated the prospective observational safety of endoscopic biopsy performed in the endoscopy unit of our patients using antithrombotic drugs.

Material and methods

Oesophagogastroduodenoscopies (OGD) and biopsies performed at a single endoscopy unit between July 2018 and February 2019 were examined in this prospective observational study. Patients receiving antithrombotic drugs due to cardiovascular and neurological reasons, who underwent an endoscopic mucosal biopsy for diagnostic purposes, were included in the study.

Results

The study was completed with 166 patients who underwent an endoscopic biopsy, from whom a total of 327 biopsies taken. The patients were examined in two groups: those “receiving antithrombotic drugs” and those who had “stopped taking antithrombotic drugs”. There was no statistically significant difference between the two groups with respect to bleeding.

Conclusions

This prospective observational study showed that performing an endoscopic biopsy without the cessation of antithrombotic drugs does not increase bleeding risk. Low-risk procedures, such as endoscopic mucosal biopsies, can be performed confidently by experienced endoscopists.

Association between matrix metalloproteinase-9 and worsening heart failure events in patients with chronic heart failure

AIMS

Matrix metalloproteinase (MMP) is up-regulated during heart failure (HF) and influences ventricular remodeling. We hypothesized that disparity between MMP-9 and tissue inhibitors of MMP-1 (TIMP-1) results in clinical manifestations and is related to prognostic risk in patients with chronic HF.

METHODS AND RESULTS

Plasma levels of MMP-9, TIMP-1, and brain natriuretic peptide (BNP) were measured in 173 patients with chronic HF. Combined endpoints of worsening HF events were assessed during follow-up (median 109 months). MMP-9 and TIMP-1 levels and the MMP-9/TIMP-1 ratio increased with increasing severity of the New York Heart Association class (P for trend = 0.003, 0.011, and 0.005, respectively). Patients with HF events (n = 35) had significantly higher MMP-9 than those without HF events (P = 0.004). Kaplan-Meier analysis demonstrated a higher probability of HF events with high MMP-9 values (>23.2 ng/mL; P = 0.005). A multivariate Cox proportional hazard model showed that high MMP-9 values were an independent predictor of HF events (hazard ratio, 3.73; 95% confidence interval (CI), 1.03-13.46; P = 0.043). In patients with lower BNP levels (≤210 pg/mL), the adjusted hazard ratio for HF events was 3.63 (95% CI, 1.20-11.02; P = 0.023) among patients with high MMP-9 values compared with patients with low BNP and low MMP-9 values.

CONCLUSIONS

MMP-9 and TIMP-1 levels correlate with the severity of chronic HF. MMP-9 is a strong predictor of HF events, suggesting that a disparity between MMP-9 and TIMP-1 levels and increased MMP-9 levels may help predict HF events.

Assessment of platelet-derived thrombogenicity with the total thrombus-formation analysis system in coronary artery disease patients receiving antiplatelet therapy

BACKGROUND

Accurate evaluation of thrombogenicity helps to prevent thrombosis and excessive bleeding. The total thrombus-formation analysis system (T-TAS) was developed for quantitative analysis of platelet thrombus formation by the use of microchips with thrombogenic surfaces (collagen, platelet chip [PL-chip]; collagen plus tissue factor, atherome chip [AR-chip]). We examined the utility of the T-TAS in the assessment of the efficacy of antiplatelet therapy in patients with coronary artery disease (CAD).

METHODS AND RESULTS

In this cross-sectional study, 372 consecutive patients admitted to the cardiovascular department were divided into three groups: patients not receiving any antiplatelet therapy (control, n = 56), patients receiving aspirin only (n = 69), and patients receiving aspirin and clopidogrel (n = 149). Blood samples were used for the T-TAS to measure the platelet thrombus-formation area under the curve (AUC) at various shear rates (1500 s(-1) [PL18 -AUC10 ] and 2000 s(-1) [PL24 -AUC10 ] for the PL-chip; 300 s(-1) [AR10 -AUC30 ] for the AR-chip). The on-clopidogrel platelet aggregation was measured by the use of P2Y12 reaction units (PRUs) with the VerifyNow system. The mean PL24 -AUC10 levels were 358 ± 111 (± standard deviation) (95% confidence interval [CI] 328.9-387.1) in the control group, 256 ± 108 (95% CI 230.5-281.5) in the aspirin group, and 113 ± 91 (95% CI 98.4-127.6) in the aspirin/clopidogrel group. In the aspirin/clopidogrel group, the PL24 -AUC10 was higher in poor metabolizers (PMs) with cytochrome P450 2C19(CYP2C19) polymorphisms (152 ± 112, 95% CI 103.4-200.6) than in the non-PM group (87 ± 74, 95% CI 73.8-100.2).

CONCLUSIONS

Our findings suggest that the PL24 -AUC10 level measured by the T-TAS is a potentially suitable index for the assessment of antiplatelet therapy in CAD patients.

Risk of bleeding after endoscopic submucosal dissection for colorectal tumors in patients with continued use of low-dose aspirin

BACKGROUND

Although Japanese guidelines proposed by the Japan Gastroenterological Endoscopy Society for endoscopic submucosal dissection (ESD) for colorectal tumors recommend continued use of low-dose aspirin (LDA), this strategy is controversial. It was our practice to interrupt LDA therapy 5-7 days before ESD until December 2010, when we instituted the new guidelines and performed ESD without interrupting LDA therapy. The aim of the present study was to confirm the validity of the noninterrupted use of LDA inpatients undergoing ESD for colorectal tumors.

METHODS

We studied 582 consecutive patients with 609 colorectal tumors who underwent ESD at Hiroshima University Hospital between January 2006 and July 2014. The patients comprised three groups: LDA-interrupted group (13 patients with 13 colorectal tumors), LDA-continued group (28 patients with 31 colorectal tumors), and no anticoagulant/antiplatelet group (541 patients with 565 colorectal tumors).

RESULTS

The en bloc resection rate was 100% (13/13) in the LDA-interrupted group and 90.3% (28/31) in the LDA-continued group. Incidences of poor bleeding control during the procedure and bleeding after the procedure were 7.7% (1/13) and 15.4% (2/13) of patients, respectively, in the LDA-interrupted group, and 3.2% (1/31) and 16.1% (5/31) of patients, respectively, in the LDA-continued group. No patients experienced ischemic events in the perioperative period.

CONCLUSIONS

Our data suggest that continued use of LDA increased the risk of bleeding after ESD for colorectal tumors compared with nonuse of anticoagulant/antiplatelets. No significant difference was seen between the LDA-continued group and the LDA-interrupted group.

New insights into the mechanisms of action of aspirin and its use in the prevention and treatment of arterial and venous thromboembolism

The antithrombotic action of aspirin has long been recognized. Aspirin inhibits platelet function through irreversible inhibition of cyclooxygenase (COX) activity. Until recently, aspirin has been mainly used for primary and secondary prevention of arterial antithrombotic events. The aim of this study was to review the literature with regard to the various mechanisms of the newly discovered effects of aspirin in the prevention of the initiation and development of venous thrombosis. For this purpose, we used relevant data from the latest numerous scientific studies, including review articles, original research articles, double-blinded randomized controlled trials, a prospective combined analysis, a meta-analysis of randomized trials, evidence-based clinical practice guidelines, and multicenter studies. Aspirin is used in the prevention of venous thromboembolism (VTE), especially the prevention of recurrent VTE in patients with unprovoked VTE who were treated with vitamin K antagonists (VKAs) or with non-vitamin K antagonist oral anticoagulants (NOACs). Numerous studies have shown that aspirin reduces the rate of recurrent VTE in patients, following cessation of VKAs or NOACs. Furthermore, low doses of aspirin are suitable for long-term therapy in patients recovering from orthopedic or other surgeries. Aspirin is indicated for the primary and secondary prevention as well as the treatment of cardiovascular diseases, including acute coronary syndrome, myocardial infarction, peripheral artery disease, acute ischemic stroke, and transient ischemic attack (especially in atrial fibrillation or mechanical heart valves). Aspirin can prevent or treat recurrent unprovoked VTEs as well as VTEs occurring after various surgeries or in patients with malignant disease. Recent trials have suggested that the long-term use of low-dose aspirin is effective not only in the prevention and treatment of arterial thrombosis but also in the prevention and treatment of VTE. Compared with VKAs and NOACs, aspirin has a reduced risk of bleeding.

Prospective analysis of risk for bleeding after endoscopic biopsy without cessation of antithrombotics in Japan

BACKGROUND AND AIM

In Japan, after the revision of the gastrointestinal endoscopic guidelines for patients taking antithrombotics, endoscopic biopsies were permitted while continuing antithrombotic treatment. However, the risk of bleeding after the biopsy with or without cessation of antithrombotics has not been fully evaluated because bleeding events are very rare. The aim of this prospective study was to evaluate the risk for bleeding after upper gastrointestinal biopsy without cessation of antithrombotics.

METHODS

Consecutive patients who underwent upper gastrointestinal endoscopic biopsy from December 2011 to March 2014 were enrolled in this study. Antithrombotic medication and its cessation status was checked at enrollment. To confirm bleeding events associated with biopsy, medical examination at the hospital or direct confirmation by telephone was done within 1 month after the biopsy.

RESULTS

Among the 3758 patients who underwent endoscopic biopsies, 394 patients (10.5%) were medicated with antithrombotics, and 286 of them (72.6% of the total antithrombotics users) did not undergo cessation. Bleeding after the biopsy occurred in six cases (0.15%, 95% CI; 0.09%∼0.22%), but there was only one case that had continued taking antithrombotics. The incidence of bleeding after biopsy was not significantly higher in the patients who had continued taking antithrombotics compared with the others (0.35% vs 0.14%, P = 0.38).

CONCLUSION

This prospective study showed that continuation of antithrombotics did not increase the bleeding risk after upper gastrointestinal endoscopic biopsy.

Long-term efficacy and safety of rabeprazole in patients taking low-dose aspirin with a history of peptic ulcers: a phase 2/3, randomized, parallel-group, multicenter, extension clinical trial

A 24-week, double-blind, clinical trial of rabeprazole for the prevention of recurrent peptic ulcers caused by low-dose aspirin (LDA) has been reported, but trials for longer than 24 weeks have not been reported. The aim of this study is to assess the long-term efficacy and safety of rabeprazole for preventing peptic ulcer recurrence on LDA therapy. Eligible patients had a history of peptic ulcers on long-term LDA (81 or 100 mg/day) therapy. Patients with no recurrence of peptic ulcers at the end of the 24-week double-blind phase with rabeprazole (10- or 5-mg once daily) or teprenone (50 mg three times daily) entered the extension phase. Rabeprazole doses were maintained for a maximum of 76 weeks, including the double-blind 24-week period and the extension phase period (long-term rabeprazole 10- and 5-mg groups). Teprenone was randomly switched to rabeprazole 10 or 5 mg for a maximum of 52 weeks in the extension phase (newly-initiated rabeprazole 10- and 5-mg groups). The full analysis set consisted of 151 and 150 subjects in the long-term rabeprazole 10- and 5-mg groups, respectively, and the cumulative recurrence rates of peptic ulcers were 2.2 and 3.7%, respectively. Recurrent peptic ulcers were not observed in the newly-initiated rabeprazole 10- and 5-mg groups. No bleeding ulcers were reported. No clinically significant safety findings, including cardiovascular events, emerged. The use of long-term rabeprazole 10- and 5-mg once daily prevents the recurrence of peptic ulcers in subjects on low-dose aspirin therapy, and both were well-tolerated.

Influence of nonsteroidal anti-inflammatory drugs on the antiplatelet effects of aspirin in rats

Low-dose aspirin acts by irreversibly acetylating internal cyclooxygenase-1 (COX-1) on platelets, thereby suppressing platelet aggregation. Because nonsteroidal anti-inflammatory drugs (NSAIDs) also inhibit COX-1, the antiplatelet effects of aspirin may be suppressed when it is co-administered with NSAIDs. In this study, the influences of ibuprofen, loxoprofen sodium and etodolac on the antiplatelet effects of aspirin were investigated in male Sprague-Dawley (SD) rats. Aspirin and/or NSAIDs were administered orally at single or multiple daily doses. Platelet aggregation (ADP and collagen were added as stimuli) and serum thromboxane B(2) (TXB(2)) concentrations were measured. The maximum inhibitions of aggregation in the aspirin before ibuprofen group were 41.0±7.8% for ADP and 38.7±5.4% for collagen at 6 h after administration; similar values were seen in the aspirin group; however, percent inhibitions in the aspirin before ibuprofen multiple administration group were lower than those in the aspirin group. Thus, the inhibitory effects of daily low-dose aspirin on platelets are competitively inhibited by the prolonged use of multiple daily doses of ibuprofen. In contrast, serum TXB(2) concentrations in all groups were lower than those in the control group (drug-free). This suggests that the relationship between the inhibition of platelet COX-1 and the suppression of platelet aggregation is nonlinear. When aspirin was administered with loxoprofen sodium, similar effects were observed; however, with etodolac, the antiplatelet effects in all groups were equal to those in the aspirin group. Accordingly, if co-administration with NSAIDs is necessary with low-dose aspirin, a selective COX-2 inhibitor, such as etodolac, should be used.

Risk assessment and aspirin use in Asian and Western populations

Objective

The aim of this review was to examine aspirin utilization, cardiovascular risk estimation, and clinical evidence for aspirin prophylaxis in Asian versus Western countries.

Methods

A literature search was performed using PubMed and the key terms “aspirin” and “Asia” or “Western”.

Results

Despite the growing burden of cardiovascular disease (CVD), aspirin is underutilized in high-risk patients in both Asian and Western countries. A number of risk estimation scores are available; however, validation is needed in countries such as Japan, India, and in South Asia. Underutilization of aspirin in Asia may be linked to an overestimation of bleeding risks. It is possible that a higher prevalence of Helicobacter pylori infection and genetic differences may make Asians more susceptible to gastrointestinal bleeding. Very low aspirin doses and even the wider use of gastroprotective agents may be the optimal approach to high-risk patients in Asia.

Conclusions

Based on the current evidence, aspirin should be used for CVD prevention when the risk:benefit ratio is favorable. A number of trials are underway, including the Diabetic Atherosclerosis Prevention by Cilostazol and Japanese Primary Prevention Project, which will provide key data on the benefits of aspirin in Asian patients at risk of CVD, and may improve aspirin utilization and risk estimation.

Platelet-derived growth factor-induced severe and chronic vasoconstriction of cerebral arteries: proposed growth factor explanation of cerebral vasospasm

OBJECTIVE

After subarachnoid hemorrhage (SAH), platelet-derived growth factor-BB (PDGF-BB) is secreted in and around the cerebral arteries. To clarify the role of PDGF-BB in the development of vasospasm after SAH, we determined whether PDGF-BB alone can cause long-lasting vasoconstriction of a severity similar to that of vasospasm. In addition, the anti-vasospastic effect of trapidil, an antagonist of PDGF-BB function, was investigated.

METHODS

We infused recombinant PDGF-BB (10 microg/mL saline as the vehicle) (n = 14) into the subarachnoid space of rabbits and analyzed alterations in the caliber of the basilar artery using repeated angiography. To study the role of PDGF-BB on the development of vasospasm, trapidil was administered continuously starting 1 hour after SAH, on day 0 (0.63-1.25 mg/kg /h or vehicle) for 47 hours (n = 24), or after the full development of cerebral vasospasm on day 2 (3.0 mg/kg/h or vehicle) for 0.5 hours (n = 17), and alterations in the caliber of the basilar artery were monitored.

RESULTS

PDGF-BB caused long-lasting vasoconstriction, with maximum constriction of 56% (P < .001) of the control value (= 100%) on day 2, resembling vasospasm seen after SAH. Prolonged administration of intravenous trapidil, starting soon after SAH, prevented the development of vasospasm in a dose-dependent manner (P < .05, .01, or .001). Intravenous or intra-arterial administration of trapidil significantly dilated vasospasm (P < .01) on day 2, at least transiently.

CONCLUSION

PDGF-BB, a growth factor synthesized in the subarachnoid space after SAH, can cause severe and long-lasting vasoconstriction. Significant prevention and resolution of vasospasm can be achieved by the PDGF-BB antagonist trapidil. We propose that excessive production of PDGF-BB, essentially aiming to repair injured arteries, causes cerebral vasospasm. Although the half-life of trapidil in serum may be shorter than that of PDGFG-BB-derived spasmogenic signaling, trapidil is a candidate drug for constructing a new therapeutic modality for preventing and resolving vasospasm.

Esophageal mucosal injury with low-dose aspirin and its prevention by rabeprazole

Aspirin is used widely as an antithrombotic drug for the prevention of cardiovascular and cerebrovascular events. Although aspirin increases the risk for gastrointestinal mucosal injury, the effect on esophageal mucosa is unclear. This study investigates whether aspirin induces esophageal mucosal injury and whether a proton-pump inhibitor can prevent such injury in relation to CYP2C19 genotypes. Fifteen healthy Japanese volunteers are dosed for 7 days in a 5-way randomly crossover trial: placebo, aspirin 100 mg, rabeprazole 10 mg, and aspirin 100 mg plus rabeprazole 10 mg either once daily or 4 times per day. All subjects undergo endoscopy and 24-hour intragastric pH monitoring on day 7. With the aspirin regimen, esophageal mucosal disorders occur in 7 patients (46.7%) (5, grade M; 2, grade A). The median 24-hour pH differs significantly among subjects who develop grade M or A gastroesophageal reflux disease and those who do not develop gastroesophageal reflux disease; the median pH in grade A gastroesophageal reflux disease is significantly lower (1.5 [range, 1.1-1.9]) than that in patients without gastroesophageal reflux disease (5.6 [range, 0.8-8.4], P = .04). Rabeprazole significantly inhibits acid secretion irrespective of CYP2C19 genotypes and decreases the incidence of aspirin-related esophageal injury and symptoms according to increasing pH value. Aspirin induces esophageal mucosal injury in an acid-dependent manner. Concomitant proton-pump inhibitor therapy may prevent advanced effects of low-dose aspirin.

Kinetic analysis of apolipoproteins in postprandial hypertriglyceridaemia rabbits

The postprandial hypertriglyceridaemia (PHT) rabbit, developed as a new animal model of metabolic syndrome, is characterized by PHT, central obesity and glucose intolerance. For detailed investigation of lipid metabolism characteristics in PHT rabbit, the plasma levels of apolipoproteins A-I, B, C-II, C-III and E were measured. Movements of apolipoproteins B100 and B48 were investigated using sodium dodecyl sulphate-polyacrylamide gel electrophoresis to determine whether postprandially increased triglyceride is exogenous or endogenous. The level of apolipoproteins A-I, B, C-II and E were increased in PHT rabbit after feeding. Apolipoproteins B100 and B48 were detected in the plasma fraction of d < 1.006 g/mL of the PHT rabbit. The postprandial increase in apolipoprotein B in the PHT rabbit reflects a numerical increase in lipoprotein particles in the blood; the increase in apolipoproteins C-II and E suggests some disturbance in lipoprotein catabolism. Apolipoprotein B48 was detected postprandially in PHT rabbits. These results suggest that delayed catabolism of exogenous lipids caused the retention of chylomicron remnants in the blood. Results also suggest that activities of the lipolytic enzyme lipoprotein lipase and hepatic triglyceride lipase were deficient and that the hepatic uptake of exogenous lipoproteins was delayed in the PHT rabbit. Especially, for examining remnant hyperlipoproteinaemia in humans, PHT rabbit is an excellent animal model for hypertriglyceridaemia research.

Impact of aspirin treatment on long-term outcome (over 10 years) after percutaneous coronary intervention

Aspirin has been shown to reduce cardiovascular morbidity and mortality following percutaneous coronary intervention (PCI). However, its effects on long-term (over 10 years) mortality have not been fully elucidated. This retrospective study recorded the patient characteristics and admission medication for all patients undergoing PCI over an 8-year period from 1984 to 1992. Follow-up information was available for 748 patients (100%) for a mean of 143.6 +/- 43.4 months. A propensity analysis was performed to adjust for presumed selection biases in the administration of aspirin. The baseline clinical characteristics were similar between the group that received aspirin and the group that did not, except for the administration of statins and PCI procedural success rate. Of the 748 patients, 535 (71.5%) received aspirin treatment at the time of PCI. During the 12-year follow-up, 54 patients died from any cause and 20 patients from cardiac death. Kaplan-Meier analysis showed that aspirin treatment led to a significant reduction in all cause mortality (10% versus 16.4%; P = 0.01) and cardiac death (3.7% versus 8.0%; P = 0.02) compared to other antiplatelet drugs. The hazard ratio (HR) for the total mortality and cardiac mortality rates was adjusted using the Cox-proportional hazard model for confounding variables and propensity score. The all cause (HR, 0.49; 95%CI [0.29-0.80], P = 0.005) and cardiac mortality rates (HR, 0.32; 95%CI [0.14-0.72], P = 0.006) for patients receiving aspirin remained lower than for those not receiving aspirin. Aspirin treatment at the time of PCI significantly reduced the risk of death from any cause and cardiac death. The administration of aspirin had a positive impact on the over 10-year long-term outcomes of patients who underwent PCI.

Aspirin for Primary Prevention of Atherosclerotic Disease in Japan

Atherosclerotic disease is the most prevalent cause of death worldwide. The ratio of coronary heart disease/cerebrovascular disease differs between Japan and Western countries and the incidence of hemorrhagic stroke and gastrointestinal bleeding is higher in Japan. Thus, the threshold for aspirin administration for primary prevention has been controversial in Japan. Much anecdotal data from Western countries and from Japan has implied that the threshold for administering aspirin to those with risk factors for coronary heart disease is higher than that recommended in Western countries, and that the potential candidates for primary prevention in Japan seem to be diabetic patients. The Japanese primary Prevention of atherosclerosis with Aspirin for Diabetes (JPAD) trial involving 2,530 patients with type 2 diabetes started in December 2002. Compared to other primary prevention trials, this trial offered an acceptable sample size, a standard aspirin dosage, and gender balance. Because stroke is the most significant component of all atherosclerotic diseases in Japan, the impact of primary prevention with aspirin on stroke should be understood. Thus, the JPAD trial should generate reliable data on primary prevention with aspirin for diabetic patients that would also be relevant to other countries.

Hereditary Postprandial Hypertriglyceridemic Rabbit Exhibits Insulin Resistance and Central Obesity

Objective— We have established a hereditary postprandial hypertriglyceridemic (PHT) rabbit. The present study was designed to define whether this rabbit model represents both insulin resistance and central obesity.

Methods and Results— Body weight, abdominal circumference, visceral fat weight, and glucose tolerance were compared between PHT and Japanese white (JW) rabbit. Plasma levels of triglycerides (TG), total cholesterol (TC), glucose, and insulin were measured before and after feeding. Abdominal circumference of PHT rabbit was larger than that of JW rabbit, with no difference in body mass index. Visceral fat accumulation was noted as obvious in mesenterium, retroperitoneal space, and epididymal area. Plasma TG and TC levels were high preprandially and markedly increased postprandially in PHT rabbit compared with JW rabbit. Although plasma glucose levels were comparable in both groups, plasma insulin levels were elevated in PHT rabbit. Glucose tolerance tests indicated that plasma insulin levels in PHT rabbit were consistently higher than in JW rabbit. A positive correlation was observed between plasma insulin levels and visceral fat weight in PHT rabbit.

Conclusions— PHT rabbit shows insulin resistance along with central obesity. PHT rabbit will serve as a model for elucidating genetic predisposition and pathophysiology in metabolic syndrome.

Systematic review and meta-analysis of adverse events of low-dose aspirin and clopidogrel in randomized controlled trials

PURPOSE

We performed a systematic review to define the relative and absolute risk of clinically relevant adverse events with the antiplatelet agents, aspirin and clopidogrel.

MATERIALS AND METHODS

Databases were searched for randomized controlled trials of low-dose aspirin (75-325 mg/day) or clopidogrel administered for cardiovascular prophylaxis. Relative risks (RR) were determined by meta-analysis of 22 trials for aspirin versus placebo and from single studies for aspirin versus clopidogrel, aspirin versus aspirin/clopidogrel, and clopidogrel versus aspirin/clopidogrel. Absolute risk increase was calculated by multiplying RR increase by the pooled weighted incidence of the control.

RESULTS

Aspirin increased the risk of major bleeding (RR=1.71; 95% confidence interval [CI], 1.41-2.08), major gastrointestinal (GI) bleeding (RR=2.07; 95% CI, 1.61-2.66), and intracranial bleeding (RR=1.65; 95% CI, 1.06-5.99) versus placebo. No difference between 75-162.5 mg/day and >162.5-325 mg/day aspirin versus placebo was seen. The absolute annual increases attributable to aspirin were major bleeding: 0.13% (95% CI, 0.08-0.20); major GI bleeding: 0.12% (95% CI, 0.07-0.19), intracranial bleeding: 0.03% (95% CI, 0.01-0.08). No study compared clopidogrel with placebo. One study showed increased major GI bleeding (but not non-GI bleeding endpoints) with aspirin versus clopidogrel (RR=1.45; 95% CI, 1.00-2.10). The absolute annual increase was 0.12% (95% CI, 0.00-0.28).

CONCLUSIONS

Low-dose aspirin increases the risk of major bleeding by approximately 70%, but the absolute increase is modest: 769 patients (95% CI, 500-1250) need to be treated with aspirin to cause one additional major bleeding episode annually. Compared with clopidogrel, aspirin increases the risk of GI bleeding but not other bleeding; however, 883 patients (95% CI, 357-infinity) would need to be treated with clopidogrel versus aspirin to prevent one major GI bleeding episode annually at a cost of over 1 million dollars.

A large-scale prospective cohort study on the current status of therapeutic modalities for acute myocardial infarction in Japan: rationale and initial results of the HIJAMI Registry

BACKGROUND

In Western countries, several multicenter collaborative studies on acute myocardial infarction (AMI) have provided much information about this disease. In Japan, on the other hand, there have been few cohort studies in which a sufficient number of Japanese patients with AMI were registered during a short period. This fact explains the absence of a database from which strategies for treating Japanese patients with AMI could be established. The purpose of this study was to build a comprehensive database on Japanese patients with AMI to elucidate their characteristics.

METHODS

Between January 1999 and June 2001, we consecutively registered all patients with AMI who were admitted to 17 participating medical institutions, including The Heart Institute of Japan, Cardiology (HIJC), Tokyo Women's Medical University. A standardized case report form was used to register all the patients.

RESULTS

A total of 3,021 consecutive patients was registered (2,136 men, 70.7%; 885 women, 29.3%) with a median age of 69 years [59, 77]. Among the patients, there were 851 elderly individuals (28.2%) > or = 76 years and 1102 patients with diabetes (36.5%). On index electrocardiogram, ST-elevation myocardial infarction was observed in 2,392 patients (79.2%). Within 24 hours after the onset of AMI, coronary angiography was conducted for 2,177 patients (72.1%). Primary percutaneous coronary intervention and coronary thrombolysis were conducted for 1,755 (58.1%) and 491 patients (16.3%), respectively, and percutaneous coronary intervention or coronary artery bypass grafting was additionally carried out in 303 patients. By the time of discharge, coronary angiography and coronary artery bypass grafting were performed in 2,659 (88.0%) and 137 patients (4.5%), respectively. During initial hospitalization, 285 patients died and the overall inhospital mortality rate was 9.4%. During hospitalization, cardiogenic shock and cardiac rupture were observed in 6.1% and 2.8% of the patients, respectively. The inhospital mortality rate is still high in patients with AMI with such mechanical complications and in elderly patients.

CONCLUSION

In our prospective cohort, we showed that Japanese patients with AMI could be characterized as (1) having a disease severity comparable with values observed in Western populations and (2) receiving early reperfusion therapy by PCI, which was used widely and safely, but nevertheless (3) exhibiting a high inhospital mortality rate. Our data indicate that further improvements in therapy for AMI in elderly patients and for AMI with mechanical complications are essential in Japan.

Trapidil enhances the slowly activating delayed rectifier potassium current and suppresses the transient inward current induced by catecholamine in Guinea pig ventricular myocytes

We examined the electrophysiological effects of trapidil on the ionic currents influencing the repolarization and on the transient inward current (ITi) that can cause triggered arrhythmia using the whole-cell patch-clamp technique in guinea pig ventricular myocytes. Trapidil shortened the action potential duration (APD) and increased the delayed rectifier potassium current (IK) in a concentration-dependent manner. The effect of trapidil on the rapidly and slowly activating components of IK (IKr and IKs, respectively) was studied by the envelope of tails test. Trapidil failed to affect IKr and selectively enhanced IKs. Trapidil increased the amplitude of the L-type Ca2+ current (ICa,L), with an acceleration of its inactivation, whereas isoproterenol, a beta-adrenoceptor agonist, increased the amplitude of the ICa,L in a different manner. Isoproterenol activated ITi; however, trapidil not only failed to facilitate ITi but also suppressed isoproterenol-induced ITi. The inhibitory effect of trapidil on isoproterenol-induced ITi is at least partly via a reduction of Ca2+ overload through an acceleration of ICa,L inactivation and/or a sarcoplasmic reticulum (SR) Ca channel modulation. These results suggest that trapidil does not prolong the QT interval and has an antiarrhythmic effect on arrhythmias elicited by triggered activity secondary to Ca2+ overload at much higher concentrations than clinical concentration.

Application of U.S. guidelines in other countries: aspirin for the primary prevention of cardiovascular events in Japan

PURPOSE

Clinical guidelines developed in the United States are used frequently in other countries without assessment of their appropriateness in non-U.S. populations. We explored the relevance of recent U.S. guidelines for the use of aspirin for the primary prevention of cardiovascular events in the Japanese population.

METHODS

From a systematic search of published data, estimates were derived for rates of coronary heart disease, hemorrhagic stroke, and major gastrointestinal bleeding for the Japanese population and for subgroups with different risk factors. Odds ratios derived from meta-analyses were used to assess the potential benefits and risks of aspirin use.

RESULTS

The estimated incidence of coronary heart disease in middle-aged men in Japan is lower than in the United States (1.57 vs. 6.0 per 1000 person-years), while that of hemorrhagic stroke is higher (1.14 vs. 0.37 per 1000 person-years). Because of higher baseline rates of hemorrhagic diseases, the expected reduction in cardiovascular events with aspirin use would be offset by a greater increase in hemorrhagic complications for women and most men in Japan, except for those with both hypertension and diabetes. To achieve the same 2:1 ratio of coronary heart disease events avoided to hemorrhagic events caused that is implied by the 3% threshold for 5-year coronary disease risk in U.S. guidelines, a 6% to 14% risk threshold, depending on patient age, seems appropriate for recommending aspirin in Japanese patients.

CONCLUSION

The thresholds of antiplatelet therapy for Asian populations should be two to five times higher than those for the U.S. population because of higher risks of hemorrhagic complications. The assumptions and implications of U.S. guidelines should be evaluated before use in other countries.

Comparing medications in a therapeutic area using an NNT model

OBJECTIVES

Clinicians are told to use the number needed to treat (NNT) to compare the benefits of therapeutic strategies, and researchers are asked to report results this way, generally without considering differences among the studies from which these were derived.

METHODS

The crude NNT currently advocated is compared to the NNT standardized for a common outcome, follow-up time, study population and comparator. An NNT model for cardiovascular disease is described as an example that addresses differences among studies of secondary prevention of cardiovascular disease. Crude NNTs are compared to those obtained from the model.

RESULTS

Follow-up in the 18 trials identified varied from 1.0 to 6.2 years; rates of cardiovascular events in the untreated subgroups ranged from 4.8% to 45.9%. The crude NNTs were more variable (9.1-163.7) than those obtained from the model (9.1-75.2). The effect of standardization was substantial in some cases, with proportional changes ranging from a 91% decrease to a 223% increase.

CONCLUSION

Using an NNT model to account for differences in study design allows for more meaningful comparisons.

Comparison of the effects of beta blockers and calcium antagonists on cardiovascular events after acute myocardial infarction in Japanese subjects

The efficacy of beta blockers in managing patients with post-acute myocardial infarction (AMI) was established based on randomized controlled trials predating the era of modern therapy in Western populations. We compared the effects of beta blockers on cardiovascular events with those of calcium antagonists in Japanese post-AMI patients on modern reperfusion therapy by performing a multicenter, prospective, randomized, open-blind end point study. Five hundred forty-five patients were assigned to the beta-blocker group and 545 patients to the calcium antagonist group. The mean follow-up period was 455 days. There was no significant difference in the incidence of cardiovascular death (1.7% vs 1.1%), reinfarction (0.9% vs 1.3%), uncontrolled unstable angina (11.0% vs 10.6%), and nonfatal stroke (0.7% vs 0.2%) between the 2 groups. However, the incidences of heart failure and coronary spasm were significantly higher in the beta-blocker group than in the calcium antagonist group (4.2% vs 1.1%, p = 0.001; 1.2% vs 0.2%, p = 0.027, respectively). We conclude that the cardiovascular event rate is substantially lower in Japanese post-AMI patients receiving modern therapy than in those reported in the West, and that there are no significant differences in the cardiovascular event rate between the beta-blocker and calcium antagonist groups.

Matrix metalloproteinase 2 is suppressed by trapidil, a CD40-CD40 ligand pathway inhibitor, in human abdominal aortic aneurysm wall

BACKGROUND

The activation of inflammatory cells and the production of matrix metalloproteinases (MMPs) are important in the pathogenesis of abdominal aortic aneurysm (AAA). Previous studies have demonstrated that the antiplatelet agent trapidil has multiple actions, including suppression of MMP expression through the inhibition of the CD40-CD40 ligand (CD40-CD40L) pathway in cultured cells. A recent clinical study suggested that trapidil might have functions beyond its antiplatelet action. Methods and results In the present study, we performed immunohistochemical analysis and semiquantitative reverse transcription-polymerase chain reaction to evaluate the effect of trapidil on the production of MMPs in cultured aortic tissues from patients with infrarenal AAA (n = 9) and control patients with aortoiliac occlusive disease (n = 7). The tissue concentrations of both MMP-2 and MMP-9 were significantly higher in AAA walls than in control aortic walls. Both trapidil and an anti-CD154 (CD40L) antibody significantly suppressed the protein production and mRNA expression of MMP-2 but did not inhibit those of MMP-9 in organ cultures of AAA wall specimens. MMP-9 was produced by macrophages and a lot of neutrophils in AAA tissues, whereas MMP-2 was derived from macrophages. CD40 was expressed on macrophages but not on neutrophils, and this expression could explain the differential effect of trapidil on the production of MMP-2 and MMP-9.

CONCLUSIONS

Trapidil, a CD40-CD40L pathway inhibitor, suppressed mRNA expression and protein production of MMP-2 in AAA tissues, suggesting a potential therapeutic approach for the prevention or treatment of AAA.

Effect of trapidil on cardiovascular events in patients with coronary artery disease (results from the Japan Multicenter Investigation for Cardiovascular Diseases-Mochida [JMIC-M])

A large-scale study was conducted to assess the effect of long-term administration of trapidil on the prognosis of patients with angiographic evidence of coronary artery disease (CAD). A large-scale, multicenter study, the Japan Multicenter Investigation for Cardiovascular Diseases-Mochida was an open-label, randomized trial of 1,743 patients with CAD who were < or =70 years old and had angiographic evidence of >25% stenosis in any coronary artery. We randomly assigned the patients to receive medical treatment either with trapidil 100 mg 3 times daily (trapidil group, n = 873) or without trapidil (control group, n = 870). The mean follow-up period was 924 days. The incidence of cardiovascular events, including cardiac death, nonfatal myocardial infarction, angina pectoris/heart failure requiring hospitalization, and cerebrovascular events was 11.1% in the trapidil group and 14.9% in the control group (relative risk 0.75, 95% confidence interval 0.58 to 0.98, p = 0.036). Thus, long-term intervention with trapidil in CAD reduces the incidence of cardiovascular events and improves the prognosis of patients with CAD.

Vascular tissue fragility assessed by a new double stain method

Although matrix metalloproteinases (MMPs) are known to be involved in the development of atherosclerosis and the instability of atheromatous plaques, much remains to be learned about their roles at the tissue level. To help clarify this area, we established a new double staining method using film in situ zymography and immunohistochemistry. Using this technique, a comprehensive analysis of the gelatinolytic activity in human vessel tissue demonstrated that gelatinolytic activity is enhanced in the shoulder region and fibrous cap at superficial areas of the atheromatous plaque in the presence of thrombolysis. Enzyme assay clarified high activity in the superficial area (7.50 +/- 5.04 U/mg weight; P < 0.001). Gelatin zymography also indicated that addition of the antiplatelet agent, trapidil, alters the amount of secretion of MMP-2 and MMP-9 and their activation ratio. This novel approach to detect the activity of gelatinases in resected tissues may aid in the selection of optimal treatment of individual patients.

Effect of trapidil on effector functions of monocytes related to atherosclerotic plaque

The infiltration and activation of inflammatory cells play an important role in the formation and stability of coronary atherosclerotic plaque in patients with acute coronary syndrome. In this study, we evaluated the effect of trapidil, an anti-platelet agent, on atheroma-related functions of human T cells and monocytes. Trapidil and anti-CD154 (CD40 ligand) antibody inhibited the increase of procoagulant activity in the mixed lymphocyte reaction; trapidil also suppressed the induction of tissue factor, monocyte chemoattractant protein-1 (MCP-1) and matrix metalloproteinase-9 in the mixed lymphocyte reaction. Trapidil did not alter CD154 expression on isolated T cells, but it diminished CD40 expression on isolated monocytes and human monocytic leukemia THP-1 cells stimulated with interferon-gamma. Moreover, trapidil reduced MCP-1 production of isolated monocytes and THP-1 cells stimulated with interferon-gamma plus CD154-transfected cells. This effect was not seen with other tested anti-platelet agents and coronary vasodilators. In conclusion, trapidil directly acts on monocytes/macrophages to lower their susceptibility to CD154 on T cells.

Antiplatelet therapy in secondary stroke prevention

This article focuses on recent data about the safety and effectiveness of antiplatelet therapies for secondary stroke prevention. Highlights include a discussion of changes in the professional labeling for aspirin and the results of a low- versus high-dose aspirin trial (Aspirin after Carotid Endarterectomy trial). Safety issues regarding aspirin also are considered. Other topics include a review of recent data on thrombotic thrombocytopenic purpura (TTP) associated with ticlopidine and a brief update on clopidogrel. A summary of discussions related to the European Stroke Prevention Study 2 data and Food and Drug Administration consideration of combination dipyridamole/aspirin therapy are presented.