Resistance to low-dose aspirin therapy among patients with acute coronary syndrome in relation to associated risk factors

No dose-response relationship of clarithromycin utilization on cardiovascular outcomes in patients with stable coronary heart disease: Analysis of Taiwan's national health insurance claims data

BACKGROUND

Clarithromycin is widely used to treat various bacterial infections and has been reported to have potential cardiovascular risk. However, it is uncertain whether this association was dose dependent and confounded by indication bias in patients with stable coronary heart disease (CHD).

METHODS

This cohort study retrospectively analyzed a national health insurance claims data from Taiwan's 2005 Longitudinal Generation Tracking Database. We used a new-user design and 1:1 propensity score matching. A total of 9,631 eligible clarithromycin users and 9,631 non-users in 2004-2015 were subject to final analysis. All patients were followed-up after receiving clarithromycin or on the matched corresponding date until occurrence of cardiovascular morbidity in the presence of competing mortality, all-cause and cause-specific mortality, or through the end of 2015. The effect of cumulative dose, exposure duration, and indications of clarithromycin on cardiovascular outcomes were also addressed.

RESULTS

Clarithromycin use, compared with non-use, was associated with higher risk for all-cause [adjusted hazard ratios (aHR), 1.43; 95% confidence interval, 1.29-1.58], cardiovascular (1.35; 1.09-1.67), and non-cardiovascular (1.45; 1.29-1.63) mortality, but not for overall cardiovascular morbidity. Further analysis of individual cardiovascular morbidity demonstrated major risk for heart events (1.25; 1.04-1.51) in clarithromycin users than non-users. However, there was no relationship of cumulative dose, exposure duration, and indications of clarithromycin on cardiovascular outcomes. Analyses of the effects over time showed that clarithromycin increased cardiovascular morbidity (1.21; 1.01-1.45), especially heart events (1.39; 1.10-1.45), all-cause (1.57; 1.38-1.80), cardiovascular (1.58; 1.20-2.08), and non-cardiovascular (1.57; 1.35-1.83) mortality during the first 3 years. Thereafter, clarithromycin effect on all outcomes almost dissipated.

CONCLUSION

Clarithromycin use was associated with increased risk for short-term cardiovascular morbidity (especially, heart events) and mortality without a dose-response relationship in patients with stable CHD, which was not dose dependent and confounded by indications. Hence, patients with stable CHD while receiving clarithromycin should watch for these short-term potential risks.

Chronic Application of Low-Dose Aspirin Affects Multiple Parameters of Three Blood Cellular Types and Antithrombin Activity: A 1:1:1 Propensity Score Matching Analysis

ABSTRACT

The mechanisms of aspirin antithrombotic actions have not been fully elucidated. We re-analyzed the data from the project Aspirin Resistance in Patients with Ischemic Atherothrombotic Diseases from April 2008 to June 2010. A total of 530 subjects were classified into 3 groups, including 40 patients without aspirin use, 24 patients taking 25-50 mg/d aspirin, and 466 patients taking 75-100 mg/d aspirin over 1 month. By 1:1:1 propensity score matching adjusting 15 primary clinical covariates, 51 patients (n = 17 per group) comprised the final sample. Hemostasis-related parameters and high platelet reactivity as measured by arachidonic acid-induced and adenosine diphosphate-induced light transmission aggregometry were compared in the 3 groups. A dose-dependent relationship was observed between aspirin and decreased high platelet reactivity incidence (PAA < 0.001, PADP < 0.01, respectively), decreased monocyte ratio (P = 0.052), increased antithrombin activity (P < 0.001), and increased platelet distribution width (P < 0.05). Aspirin at 25-50 mg/d is related to the lowest red blood cell (RBC) count, whereas 75-100 mg/d aspirin showed the highest RBC count among the 3 groups (4.52 ± 0.35 × 1012/L vs. 4.35 ± 0.57 × 1012/L vs. 4.80 ± 0.59 × 1012/L, P = 0.046). Our finding demonstrated that aspirin exerts its antithrombotic effects at least by antiplatelet function, enhancing antithrombin activity and suppressing monocytes in vivo. In addition, 3 blood cell types, namely RBCs, monocytes, and platelets, are involved in the aspirin antithrombotic mechanism. The cellular response to aspirin partially enhances the antithrombotic effects while partially inhibiting the effects.

PFA-100-measured aspirin resistance is the predominant risk factor for hospitalized cardiovascular events in aspirin-treated patients: A 5-year cohort study

WHAT IS KNOWN AND OBJECTIVE

Aspirin therapy is the clinical gold standard for the prevention of cardiovascular events. However, cardiovascular events still develop in some patients undergoing aspirin therapy. Many laboratory methods exist for measuring aspirin resistance. Using the platelet Function Analyzer (PFA)-100 system, we aimed to determine the effect of aspirin resistance on hospitalized cardiovascular events (hCVE) in a 5-year follow-up cohort. We also sought to determine the impact of aspirin resistance on the relationship between common cardiovascular risk factors and cardiovascular hospitalization.

METHOD

Aspirin resistance was evaluated in aspirin-treated patients from the outpatient department. A total of 465 patients during a 5-year follow-up period were included in this study. The primary endpoint of the study was hospitalization for any acute cardiovascular event. The prevalence and associated risk factors of acute cardiovascular events were evaluated.

RESULTS AND DISCUSSION

Aspirin resistance was prevalent in 91 (20.0%) of 465 patients. Prior hospitalization history of cardiovascular events was highly associated with aspirin resistance (P = .001). At the 5-year follow-up, cardiovascular events were found to have developed in 11 patients (8 stroke and 3 myocardial infarction) who exhibited aspirin resistance (12.1%) and in 9 (4 stroke and 5 myocardial infarction) patients who did not exhibit aspirin resistance (2.4%) (P < .001). At the 5-year follow-up, multivariate logistic regression analysis results showed a strong association between aspirin resistance and cardiovascular events (adjusted odds ratio 4.28; 95% CI: 1.64-11.20; P = .03).

WHAT IS NEW AND CONCLUSION

PFA-100 measurements of aspirin resistance correlate with hCVE, as evidenced by both the past medical history and the 5-year follow-up. The logistic regression analysis results showed that aspirin resistance plays a larger role in hospitalized cardiovascular disease than do other cardiovascular risk factors.

Obesity and Cardiovascular Disease: a Risk Factor or a Risk Marker?

In the USA, 69 % of adults are either overweight or obese and 35 % are obese. Obesity is associated with an increased incidence of various cardiovascular disorders. Obesity is a risk marker for cardiovascular disease, in that it is associated with a much higher prevalence of comorbidities such as diabetes, hypertension, and metabolic syndrome, which then increase the risk for cardiovascular disease. However, in addition, obesity may also be an independent risk factor for the development of cardiovascular disease. Furthermore, although obesity has been shown to be an independent risk factor for several cardiovascular diseases, it is often associated with improved survival once the diagnosis of the cardiovascular disease has been made, leading to the term "obesity paradox." Several pathways linking obesity and cardiovascular disease have been described. In this review, we attempt to summarize the complex relationship between obesity and cardiovascular disorders, in particular coronary atherosclerosis, heart failure, and atrial fibrillation.

Antiplatelet treatment in essential hypertension: where do we stand?

Antiplatelet agents represent a cornerstone in the management of patients at increased cardiovascular risk. Essential hypertension is considered a major public health problem leading to increased cardiovascular morbidity and mortality. The majority of patients with essential hypertension exhibit also additional cardiovascular risk factors and present with increased platelet activation. Despite recent innovations in the field of antiplatelet treatment and the introduction of novel agents, the role of antiplatelet treatment in patients with essential hypertension remains understudied. This review aims to shed light on novel experimental and clinical data in the evolving field of antiplatelet treatment in essential hypertension. In particular, recent data regarding aspirin, clopidogrel, novel P2Y12 inhibitors, and other agents with potential antiplatelet effects are critically reviewed.

Aspirin in the prevention of cardiovascular events in patients with diabetes

Diabetes imparts a substantial increased risk for cardiovascular disease-related mortality and morbidity. Because of this, current medical guidelines recommend prophylactic treatment with once-daily, low-dose aspirin (acetylsalicylic acid) for primary and secondary prevention of cardiovascular (CV) events in high-risk patients. However, only modest reductions in CV events and mortality have been observed with once-daily aspirin treatment in patients with diabetes, including patients with a previous CV event, perhaps because of disparity between aspirin pharmacokinetics and diabetes-related platelet abnormalities. Once-daily aspirin irreversibly inactivates platelets for only a short duration (acetylsalicylic acid half-life, approximately 15-20 minutes), after which time newly generated, active platelets enter the circulation and weaken aspirin's effect. Platelets from patients with diabetes are more reactive and are turned over more rapidly than platelets from normal individuals; the short inhibitory window provided by once-daily aspirin may therefore be insufficient to provide 24-h protection against CV events. Alternative conventional aspirin regimens (e.g. higher daily dose, twice-daily dosing, combination with clopidogrel) and newer formulations (e.g. 24-h, extended-release) have been proposed to overcome the apparent limited efficacy of conventional aspirin in patients with diabetes; however, tolerability concerns and limited clinical efficacy data need to be taken into account when considering the use of such regimens.

Drug delivery and therapeutic impact of extended-release acetylsalicylic acid

Current treatment guidelines recommend once-daily, low-dose acetylsalicylic acid (ASA; aspirin) for secondary prevention of cardiovascular events. However, the anti-thrombotic benefits of traditional ASA formulations may not extend over a 24-h period, especially in patients at high risk for a recurrent cardiovascular event. A next-generation, extended-release ASA formulation (ER-ASA) has been developed to provide 24-h anti-thrombotic coverage with once-daily dosing. The pharmacokinetics of ER-ASA indicates slower absorption and prolonged ASA release versus immediate-release ASA, with a favorable safety profile. ER-ASA minimizes systemic ASA absorption and provides sustained antiplatelet effects over a 24-h period.

Antiplatelet resistance and the role of associated variables in stable patients treated with stenting

Introduction

Nowadays, clopidogrel and acetylsalicylic acid (ASA) have become routinely applied therapies in percutaneous coronary interventions (PCI) with stenting.

Aim

Numerous variables can interfere with antiplatelet responsiveness, so we aimed to investigate the role of different variables associated with ASA or clopidogrel resistance in stable coronary artery disease.

Material and methods

A total of 207 patients undergoing elective PCI were included in the analysis. All patients received a loading dose of clopidogrel and ASA during PCI procedure and followed by dual antiplatelet therapy. Clopidogrel and ASA resistance were measured by impedance aggregometry method.

Results

Of the patients, 19.8% had clopidogrel resistance, 18.8% had ASA resistance, 9.2% had both clopidogrel and ASA resistance, and 71.5% were responsive to both drugs. In multivariate analysis, platelet count, angiotensin receptor blocker (ARB) use, and ASA resistance were independent variables associated with clopidogrel resistance, and clopidogrel resistance was the only variable associated with ASA resistance. In differentiating whether clopidogrel resistance exists or not, optimum ASA aggregometry response cut-off values were specified, and in differentiating whether ASA resistance exists or not, optimum clopidogrel aggregometry response cut-off values were specified.

Conclusions

In this study, there was a higher incidence of low responsiveness to ASA when there was a low response to clopidogrel, and vice versa. Angiotensin receptor blocker use, platelet count, and ASA resistance were independent variables associated with clopidogrel resistance. Clopidogrel resistance was the only independent variable associated with ASA resistance. Angiotensin receptor blocker use seems to an independent risk factor for clopidogrel resistance in this study, but this result needs to be verified in other studies.

Obesity and coronary artery disease: evaluation and treatment

With the increasing prevalence of obesity, clinicians are now facing a growing population of patients with specific features of clinical presentation, diagnostic challenges, and interventional, medical, and surgical management. After briefly discussing the effect of obesity on atherosclerotic burden in this review, we will focus on strategies clinicians might use to ensure better outcomes when performing revascularization in obese and severely obese patients. These patients tend to present comorbidities at a younger age, and their anthropometric features might limit the use of traditional cardiovascular risk stratification approaches for ischemic disease. Alternative techniques have emerged, especially in nuclear medicine. Positron emission tomography-computed tomography might be the diagnostic imaging technique of choice. When revascularization is considered, features associated with obesity must be considered to guide therapeutic strategies. In percutaneous coronary intervention, a radial approach should be favoured, and adequate antiplatelet therapy with new and more potent agents should be initiated. Weight-based anticoagulation should be contemplated if needed, with the use of drug-eluting stents. An "off-pump" approach for coronary artery bypass grafting might be preferable to the use of cardiopulmonary bypass. For patients who undergo bilateral internal thoracic artery grafting, harvesting using skeletonization might prevent deep sternal wound infections. In contrast to percutaneous coronary intervention, lower surgical bleeding has been observed when lean body mass is used for perioperative heparin dose determination.

Correlation between the severity of coronary artery lesions and levels of estrogen, hs-CRP and MMP-9

The aim of this study was to investigate the correlation between the severity of coronary artery lesions in patients with acute coronary syndromes (ACS) and levels of estrogen, high-sensitivity C-reactive protein (hs-CRP) and matrix metalloproteinase-9 (MMP-9). A total of 65 patients with ACS, 33 patients with stable angina pectoris (SAP) and 36 healthy controls were randomly enrolled. Patients with ACS were subdivided into two groups: Acute myocardial infarction (AMI; n=30) and unstable angina pectoris (UAP; n=35). Serum levels of estrogen, hs-CRP and MMP-9 were detected in the four groups of subjects. Serum estrogen levels in patients with AMI, UAP and SAP were significantly lower than those in the control group (P<0.05). Estrogen levels were also significantly different among the AMI, UAP and SAP groups (P<0.05), with a progressive increase across the three respective groups. Compared with healthy subjects, patients with AMI had the highest levels of hs-CRP and MMP-9, followed in descending order by those with UAP and SAP (P<0.05). Levels of hs-CRP and MMP-9 were also significantly different among the AMI, UAP and SAP groups (P<0.05). Serum estrogen levels were negatively correlated with hs-CRP and MMP-9 levels (r=−0.6634 and −0.6878, respectively; both P<0.05). hs-CRP and MMP-9 levels correlated positively (r=0.7208, P<0.05). The number of stenosed coronary vessels was negatively correlated with estrogen levels (r=−0.6467, P<0.05), and positively correlated with hs-CRP and MMP-9 levels (r=0.6519 and 0.6835, respectively; both P<0.05). In conclusion, serum estrogen, hs-CRP and MMP-9 levels were significantly correlated with the severity of coronary artery lesions. There was also a significant correlation between serum estrogen, hs-CRP and MMP-9 levels. These data indicate that serum estrogen, hs-CRP and MMP-9 have the potential to be used as biomarkers for evaluating the severity of coronary artery lesions and the stability of coronary artery plaques.

Prevalence of high on-treatment platelet reactivity in diabetic patients treated with aspirin

BACKGROUND

Randomized controlled trials have shown that ≤ 100 mg aspirin daily is not effective for primary prevention of cardiovascular events in diabetes; however, clinical and pharmacologic evidence suggests these patients need >100 mg for adequate antiplatelet activity. Although high on-treatment platelet reactivity (HTPR) could explain the lack of benefit, prevalence of HTPR in diabetes is not known. This systematic review examined the relationship between daily aspirin dose and prevalence of HTPR in patients with diabetes.

METHODS

Three electronic databases were searched until May 2013 using database-appropriate terms for aspirin, resistance, and diabetes. Studies were included if prevalence of HTPR was reported according to daily dose and diabetes status. Patients were stratified by daily aspirin dose and the weighted mean prevalence across studies was calculated. Where appropriate, pooled relative risks (RR) were calculated using a random-effects model.

RESULTS

Data were available from 31 studies that enrolled 2147 diabetic patients. Overall, prevalence of HTPR was 21.9% (95% confidence interval [CI], 15.2%-28.5%) in diabetic patients and 15.8% (95% CI, 11.4%-20.3%) in nondiabetic patients (pooled RR 1.36; 95% CI, 1.08-1.71; I(2) 56%). Prevalence appeared to be dose related, with 398 (23.6%) of 1689 diabetic patients using ≤ 100 mg daily having HTPR compared with 64 (12.3%) of 518 diabetic patients using 101-325 mg daily (pooled RR 1.70; 95% CI, 1.07-2.72; I(2) 0%).

CONCLUSIONS

Although these observations should be verified in a clinical trial, the possibility that 1 in 4 patients have HTPR with doses commonly used in diabetes could have significant implications on overall effectiveness of aspirin.