The prevalence, risk factors and prognosis of aspirin resistance in elderly male patients with cardiovascular disease

N-Terminal Pro-Brain Natriuretic Peptide and Right Ventricular Diameter Are Related to Aspirin Resistance in Coronary Artery Disease Patients

Background and Objectives: Resistance to ASA (ASAres) is a multifactorial phenomenon defined as insufficient reduction of platelet reactivity through incomplete inhibition of thromboxane A2 synthesis. The aim is to reassess the prevalence and predictors of ASAres in a contemporary cohort of coronary artery disease (CAD) patients (pts) on stable therapy with ASA, 75 mg o.d. Materials and Methods: We studied 205 patients with stable CAD treated with daily dose of 75 mg ASA for a minimum of one month. ASAres was defined as ARU (aspirin reaction units) ≥550 using the point-of-care VerifyNow Aspirin test. Results: ASAres was detected in 11.7% of patients. Modest but significant correlations were detected between ARU and concentration of N-terminal pro-brain natriuretic peptide (NT-proBNP) (r = 0.144; p = 0.04), body weight, body mass index, red blood cell distribution width, left ventricular mass, and septal end-systolic thickness, with trends for left ventricular mass index and prothrombin time. In multivariate regression analysis, log(NT-proBNP) was identified as the only independent predictor of ARU—partial r = 0.15, p = 0.03. Median concentrations of NT-proBNP were significantly higher in ASAres patients (median value 311.4 vs. 646.3 pg/mL; p = 0.046) and right ventricular diameter was larger, whereas mean corpuscular hemoglobin concentration was lower as compared to patients with adequate response to ASA. Conclusions: ASAres has significant prevalence in this contemporary CAD cohort and NT-proBNP has been identified as the independent correlate of on-treatment ARU, representing a predictor for ASAres, along with right ventricular enlargement and lower hemoglobin concentration in erythrocytes.

Effects of cigarette smoking on older chinese men treated with clopidogrel monotherapy or aspirin monotherapy: a prospective study

We investigated the comparative effects of smoking status on outcomes in older Chinese men receiving aspirin or clopidogrel monotherapy. This was a prospective observational study of outcomes in 668 men aged ≥ 60 years undergoing annual health examination in the Chinese People's Liberation Army General Hospital from March-April 2017. All patients received regular treatment with aspirin or clopidogrel. Platelet aggregation and phenotyping for rs762551 were measured in all patients. We recorded all major adverse cardiovascular and cerebrovascular events; namely, all-cause death, myocardial infarction, stroke, transient ischemic attack, and unstable angina. In the clopidogrel subgroup, homozygous carriers (AA) of the CYP1A2*1F gene (rs762551, 163C>A) appeared more frequently in smokers than in nonsmokers (45.6% vs 32.7%, p = .035). Adenosine diphosphate-induced platelet aggregation using light transmittance aggregometry was lower in smokers compared with nonsmokers (44.97 ± 20.05% vs 51.98 ± 19.38%, respectively; p = .0018). Smokers (n = 103) had a decreased risk of major adverse cardiovascular and cerebrovascular events, compared with nonsmokers [n = 159; hazard ratio, 0.466; 95% confidence interval: 0.262-0.829, p = .008]. In the aspirin subgroup, AA-induced platelet aggregation showed no significant difference regarding smoking vs nonsmoking status (30.90 ± 32.21 vs 29.78 ± 31.47, respectively; p = .771). However, we saw a significant increase in adverse clinical events in the smoking group (n = 148) compared with the nonsmoking group (n = 258; hazard ratio = 1.907, 95% confidence interval: 1.128-3.225; p = .016). In older Chinese men, active smokers benefitted from clopidogrel therapy compared with aspirin. Long-term cigarette smoking may contribute to increased variations in CYP1A2*1F, but the variations do not fully explain the smoking paradox.

Establishing a predictive model for aspirin resistance in elderly Chinese patients with chronic cardiovascular disease

Background

Resistance to anti-platelet therapy is detrimental to patients. Our aim was to establish a predictive model for aspirin resistance to identify high-risk patients and to propose appropriate intervention.

Methods

Elderly patients (n = 1130) with stable chronic coronary heart disease who were taking aspirin (75 mg) for > 2 months were included. Details of their basic characteristics, laboratory test results, and medications were collected. Logistic regression analysis was performed to establish a predictive model for aspirin resistance. Risk score was finally established according to coefficient B and type of variables in logistic regression. The Hosmer–Lemeshow (HL) test and receiver operating characteristic curves were performed to respectively test the calibration and discrimination of the model.

Results

Seven risk factors were included in our risk score. They were serum creatinine (> 110 μmol/L, score of 1); fasting blood glucose (> 7.0 mmol/L, score of 1); hyperlipidemia (score of 1); number of coronary arteries (2 branches, score of 2; ≥ 3 branches, score of 4); body mass index (20–25 kg/m², score of 2; > 25 kg/m², score of 4); percutaneous coronary intervention (score of 2); and smoking (score of 3). The HL test showed P ≥ 0.05 and area under the receiver operating characteristic curve ≥ 0.70.

Conclusions

We explored and quantified the risk factors for aspirin resistance. Our predictive model showed good calibration and discriminative power and therefore a good foundation for the further study of patients undergoing anti-platelet therapy.

Endogenous Fibrinolysis: An Important Mediator of Thrombus Formation and Cardiovascular Risk

Most acute cardiovascular events are attributable to arterial thrombosis. Plaque rupture or erosion stimulates platelet activation, aggregation, and thrombosis, whilst simultaneously activating enzymatic processes that mediate endogenous fibrinolysis to physiologically maintain vessel patency. Interplay between these pathways determines clinical outcome. If proaggregatory factors predominate, the thrombus may propagate, leading to vessel occlusion. However, if balanced by a healthy fibrinolytic system, thrombosis may not occur or cause lasting occlusion. Despite abundant evidence for the fibrinolytic system regulating thrombosis, it has been overlooked compared with platelet reactivity, partly due to a lack of techniques to measure it. We evaluate evidence for endogenous fibrinolysis in arterial thrombosis and review techniques to assess it, including biomarkers and global assays, such as thromboelastography and the Global Thrombosis Test. Global assays, simultaneously assessing proaggregatory and fibrinolytic pathways, could play a role in risk stratification and in identifying impaired fibrinolysis as a potential target for pharmacological modulation.

Platelet-reactivity tests identify patients at risk of secondary cardiovascular events: a systematic review and meta-analysis

BACKGROUND

Antiplatelet therapy is the standard treatment for the prevention of cardiovascular events (CVEs). High on-treatment platelet reactivity (HPR) is a risk factor for secondary CVEs in patients prescribed aspirin and/or clopidogrel. The present review and meta-analysis was aimed at assessing the ability of individual platelet-function tests to reliably identify patients at risk of developing secondary CVEs.

METHODS AND RESULTS

A systematic literature search was conducted to identify studies on platelet-reactivity measurements and CVEs. The main inclusion criteria were: (i) prospective study design; (ii) study medication, including aspirin and/or clopidogrel; and (iii) a platelet-function test being performed at baseline, before follow-up started. Of 3882 identified studies, 102 (2.6%; reporting on 44 098 patients) were included in the meta-analysis. With regard to high on-aspirin platelet reactivity (HAPR), 22 different tests were discussed in 55 studies (22 441 patients). Pooled analysis showed that HAPR was diagnosed in 22.2% of patients, and was associated with an increased CVE risk (relative risk [RR] 2.09; 95% confidence interval [CI] 1.77-2.47). Eleven HAPR tests independently showed a significantly increased CVE risk in patients with HAPR as compared with those with normal on-aspirin platelet reactivity. As regards high on-clopidogrel platelet reactivity (HCPR), 59 studies (34 776 patients) discussed 15 different tests, and reported that HCPR was present in 40.4% of patients and was associated with an increased CVE risk (RR 2.80; 95% CI 2.40-3.27). Ten tests showed a significantly increased CVE risk.

CONCLUSIONS

Patients with HPR are suboptimally protected against future cardiovascular complications. Furthermore, not all of the numerous platelet tests proved to be able to identify patients at increased cardiovascular risk.

Non-HDL cholesterol is an independent risk factor for aspirin resistance in obese patients with type 2 diabetes

OBJECTIVE

We evaluated the prevalence of aspirin resistance and predictive factors for aspirin resistance in Korean type 2 diabetes patients.

APPROACH AND RESULTS

A total of 1045 type 2 diabetes patients from 11 hospitals who were taking aspirin (100 mg/day for ≥2 weeks) and no other antiplatelet agents were studied to evaluate aspirin resistance. Aspirin resistance was measured in aspirin reaction units using VerifyNow(®). Aspirin resistance was defined as ≥550 aspirin reaction units. Aspirin resistance was detected in 102 of the 1045 subjects (prevalence 9.8%). Aspirin resistance was associated with total cholesterol (P = 0.013), LDL-cholesterol (P = 0.028), and non-HDL cholesterol (P = 0.008) concentrations in univariate analysis. In multivariate logistic regression analysis, only non-HDL cholesterol was associated with aspirin resistance in obese (BMI >25 kg/m(2)) type 2 diabetes patients (adjusted odds ratio 3.55, 95% CI: 1.25-10.05, P = 0.017).

CONCLUSIONS

The prevalence of aspirin resistance in Korean type 2 diabetes patients is 9.8%. Non-HDL cholesterol is an independent risk factor for aspirin resistance, especially in obese type 2 diabetes patients.

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.

Relation of aspirin response to age in patients with stable coronary artery disease

Recent studies have suggested that clopidogrel response may vary significantly with age. Limited data are available exploring the age dependency of ex vivo aspirin response in young and old patients with stable coronary artery disease. Patients with stable coronary artery disease (n = 583) who had been treated with aspirin 75 to 325 mg/day for ≥1 week were recruited from a general cardiology practice. The study cohort was divided into 2 groups: patients aged <75 years (n = 438) and patients aged ≥75 years (n = 145). Aspirin response was determined using the VerifyNow Aspirin Test, and resistance was defined as ≥500 or 550 aspirin reaction units (ARU). The independent predictive value of age on VerifyNow score (as a continuous function) was determined using multivariate linear regression, adjusted for gender, body mass index, and diabetes mellitus. Younger and older patients had similar baseline clinical profiles, including relative doses of aspirin therapy. The mean VerifyNow Aspirin Test score was significantly higher in patients aged ≥75 years: 450 ± 54 versus 434 ± 53 ARU (p = 0.0007). After accounting for the primary covariates, age remained a predictor of VerifyNow score (p = 0.007). Aspirin resistance on the basis of the 500-ARU cutoff was higher in older patients (19% vs 11%, p = 0.009), but there was no difference when the 550-ARU cutoff was used (7% vs 5%, p = 0.40). In conclusion, aspirin response differs significantly by age in patients with stable CAD.

Frequency, risk factors, prognosis, and genetic polymorphism of the cyclooxygenase-1 gene for aspirin resistance in elderly Chinese patients with cardiovascular disease

BACKGROUND

Cardiovascular disease (CVD) is an important cause of mortality in elderly patients worldwide. Aspirin resistance has been well reported in CVD.

OBJECTIVE

The frequency, risk factors, prognosis, and genetic polymorphism of the cyclooxygenase-1 (COX-1) gene for aspirin resistance have not been reported in elderly patients with CVD. We therefore undertook this study to evaluate these associations among elderly Chinese patients with CVD.

METHODS

Four hundred thirty-one elderly Chinese patients with CVD receiving daily aspirin therapy (≥75 mg) over 1 month were enrolled. Platelet aggregation was measured by light transmission aggregometry (LTA) and thromboelastography platelet mapping assay (TEG) using arachidonic acid (AA) as a stimulus. The median follow-up was 1.8 years.

RESULTS

After the median follow-up, aspirin-resistant patients were at an increased risk of the composite endpoint compared to nonresistant patients by LTAAA + TEGAA (23.7 vs. 9.2%, p = 0.025). Additionally, Cox proportional hazards regression modeling demonstrated that aspirin resistance and cerebrovascular disease were associated with major adverse long-term outcomes (HR for aspirin resistance = 2.31, 95% CI 1.11-4.81, p = 0.026). The variant G-allele of COX-1 rs1330344 (-1676 A/G) significantly increased the risk of aspirin resistance defined by LTAAA + TEGAA (OR = 1.82, 95% CI 1.13- 2.92, p = 0.01).

CONCLUSIONS

Aspirin resistance, evaluated by LTAAA + TEGAA, is associated with an increased risk of adverse clinical events in elderly Chinese patients with CVD. The variant G-allele of COX-1 rs1330344 is significantly associated with aspirin resistance defined by LTAAA + TEGAA.