Impact of smoking on long-term outcomes in patients with atherosclerotic vascular disease treated with aspirin or clopidogrel: insights from the CAPRIE trial (Clopidogrel Versus Aspirin in Patients at Risk of Ischemic Events)

Investigation of smoking on the antiplatelet response to clopidogrel: Unravelling the smoker's paradox

The intricate relationship between smoking and the effects of the antiplatelet drug clopidogrel has been termed the "smoker's paradox". This paradox details the enhanced efficacy of clopidogrel in smokers compared to non-smokers. This review begins with an exploration of the proposed mechanisms of the smoker's paradox, particularly drawing attention to the induction of cytochrome P450 (CYP) isoenzymes via tobacco smoke, specifically the enzymes CYP1A2 and CYP2C19. Moreover, an investigation of the effects of genetic variability on the smoker's paradox was undertaken from both clinical and molecular perspectives, delving into the effects of ethnicity and genetic polymorphisms. The intriguing role of CYP1A2 genotypes and the response to clopidogrel in smoking and non-smoking populations was examined conferring insight into the individuality rather than universality of the smoker's paradox. CYP1A2 induction is hypothesised to elucidate the potency of smoking in exerting a counteracting effect in those taking clopidogrel who possess CYP2C19 loss of function polymorphisms. Furthermore, we assess the comparative efficacies of clopidogrel and other antiplatelet agents, namely prasugrel and ticagrelor. Studies indicated that prasugrel and ticagrelor provided a more consistent effect and further reduced platelet reactivity compared to clopidogrel within both smoking and non-smoking populations. Personalised dosing was another focus of the review considering patient comorbidities, genetic makeup, and smoking status with the objective of improving the antiplatelet response of those taking clopidogrel. In summation, this review provides insight into multiple areas of research concerning clopidogrel and the smoker's paradox taking into account proposed mechanisms, genetics, other antiplatelet agents, and personalised dosing.

Dual Antiplatelet Therapy or Antiplatelet Plus Anticoagulant Therapy in Patients with Peripheral and Chronic Coronary Artery Disease: An Updated Review

Despite evidence-based therapies, patients presenting with atherosclerosis involving more than one vascular bed, such as those with peripheral artery disease (PAD) and concomitant coronary artery disease (CAD), constitute a particularly vulnerable group characterized by enhanced residual long-term risk for major adverse cardiac events (MACE), as well as major adverse limb events (MALE). The latter are progressively emerging as a difficult outcome to target, being correlated with increased mortality. Antithrombotic therapy is the mainstay of secondary prevention in both patients with PAD or CAD; however, the optimal intensity of such therapy is still a topic of debate, particularly in the post-acute and long-term setting. Recent well-powered randomized clinical trials (RCTs) have provided data in favor of a more intense antithrombotic therapy, such as prolonged dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor or a therapy with aspirin combined with an anticoagulant drug. Both approaches increase bleeding and selection of patients is a key issue. The aim of this review is, therefore, to discuss and summarize the most up-to-date available evidence for different strategies of anti-thrombotic therapies in patients with chronic PAD and CAD, particularly focusing on studies enrolling patients with both types of atherosclerotic disease and comparing a higher- versus a lower-intensity antithrombotic strategy. The final objective is to identify the optimal tailored approach in this setting, to achieve the greatest cardiovascular benefit and improve precision medicine.

The role of clopidogrel resistance-related genetic and epigenetic factors in major adverse cardiovascular events among patients with acute coronary syndrome after percutaneous coronary intervention

Despite patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) and receiving clopidogrel therapy, some patients still experience major adverse cardiovascular events (MACEs). Clopidogrel resistance, which may be regulated by genetic and epigenetic factors, may play a role in MACEs. This study aimed to determine the association between genetic (CYP2C19 and P2Y12 polymorphisms) and epigenetic (DNA methylation of CYP2C19 and P2Y12 and miRNA-26a expression) factors and their effects on MACEs among post-PCI patients. Post-PCI patients who received a standard dosage of clopidogrel at Harapan Kita Hospital between September 2018 and June 2020 were included in this study. MACEs were observed in patients within 1 year after PCI. Platelet aggregation was assessed using light transmission aggregometry (LTA). DNA methylation of CYP2C19 and P2Y12 was assessed using the bisulfite conversion method. CYP2C19 and P2Y12 polymorphisms and miRNA-26a expression were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). Among a total of 201 subjects, 49.8% were clopidogrel-resistant, and 14.9% experienced MACEs within 1 year after PCI (death was 7.5%). Hypomethylation of CYP2C19 (p = 0.037) and miRNA-26a upregulation (p = 0.020) were associated with clopidogrel resistance. CYP2C19^*2/^*3 polymorphisms (p = 0.047) were associated with MACEs in 1 year. This study demonstrated that hypomethylation of CYP2C19 and miRNA-26a upregulation increased the risk of clopidogrel resistance in post-PCI patients, but there was no correlation between clopidogrel resistance and MACEs. However, CYP2C19^*2/^*3 polymorphisms were the factors that predicted MACEs within 1 year.

Influence of CYP2C19 genetic variants and smoking on dual antiplatelet efficacy in patients with coronary artery disease

Introduction

This study aimed to investigate the effects of smoking and CYP2C19 gene polymorphism on antiplatelet therapy to specify the most optimized and accurate antiplatelet therapy for different populations.

Methods

This study included 6,353 patients with coronary artery disease (CAD). In total, 2,256 (35.5%) were smokers and 4,097 (64.5%) were non-smokers. Patients carrying a CYP2C19*2 or *3 allele were considered loss-of-function (LOF) allele carriers. The medical history of patients who had undergone percutaneous coronary intervention (PCI) at Beijing Anzhen Hospital was recorded. The primary endpoint was major adverse cardiovascular or cerebrovascular events (MACCE) during the 6-month follow-up period. A Cox regression model was used to assess the interactions between antiplatelet efficacy and CYP2C19 LOF allele carrier status, stratified by smoking status.

Results

Compared to clopidogrel plus aspirin, ticagrelor plus aspirin reduced the MACCE recurrence risk in non-smokers (carrier: 6.0 vs. 2.0%, hazard ratio 0.298, 95% confidence interval 0.204-0.635, P < 0.0001; non-carrier: 5.8 vs. 2.1%, hazard ratio 0.358, 95% confidence interval 0.189-0.678, P = 0.002), and not in smokers. Similar results were discovered regarding the recurrence rate for hospitalization for ischemic cardiac events in non-smokers. No apparent difference was discovered in the bleeding events in either group. There were no significant associations between antiplatelet medication and CYP2C19 LOF allele carrier status for the MACCE recurrence risk among smokers (P = 0.943, respectively) or non-smokers (P = 0.774, respectively).

Conclusion

In patients with CAD after PCI, ticagrelor plus aspirin lowered the MACCE recurrence risk in CYP2C19 LOF allele carriers and non-carriers compared with clopidogrel plus aspirin alone among non-smokers. The efficacy of antiplatelet therapy varies between CYP2C19 LOF allele carrier status. No significant interaction between CYP2C19 LOF allele carrier status and antiplatelet effectiveness was observed. However, caution should be used to interpret our results considering the many limitations of our investigation.

Subsequent ischemic stroke and tobacco smoking: A secondary analysis of the POINT trial

Background:

The aim of this study was to determine the effect of smoking status on subsequent stroke risk in patients with minor ischemic stroke or TIA and to determine whether smoking modifies the effect of clopidogrel-based DAPT on subsequent stroke risk.

Methods:

This was a post-hoc analysis of the Platelet Oriented Inhibition in New TIA and Minor Ischemic Stroke (POINT) trial, which had a 90-day follow-up period. We used multivariable Cox regression and subgroup interaction analysis to determine the effect of smoking on the risk of subsequent ischemic stroke and major hemorrhage, respectively.

Results:

Data from 4877 participants enrolled in the POINT trial were analyzed. Among these, 1004 were current smokers and 3873 were non-smokers at the time of index event. Smoking was associated with a non-significant trend toward an increased risk of subsequent ischemic stroke during follow up (adjusted HR, 1.31 (95% CI, 0.97–1.78), p = 0.076). The effect of clopidogrel on ischemic stroke did not differ between non-smokers (HR, 0.74 (95% CI, 0.56–0.98), p = 0.03) and smokers (HR, 0.63 (95% CI, 0.37–1.05), p = 0.078), p for interaction = 0.572. Similarly, the effect of clopidogrel on major hemorrhage did not differ between non-smokers (hazard ratio, 1.67 (95% CI, 0.40–7.00), p = 0.481) and smokers (HR, 2.59 (95% CI, 1.08–6.21), p = 0.032), p for interaction = 0.613.

Conclusions:

In this post-hoc analysis of the POINT trial we found that the effect of clopidogrel on reducing subsequent ischemic stroke as well as risk of major hemorrhage did not depend on smoking status, indicating that smokers benefit to a similar degree from DAPT as non-smokers.

Impact of Smoking Status on Mortality in STEMI Patients Undergoing Mechanical Reperfusion for STEMI: Insights from the ISACS-STEMI COVID-19 Registry

The so-called “smoking paradox”, conditioning lower mortality in smokers among STEMI patients, has seldom been addressed in the settings of modern primary PCI protocols. The ISACS−STEMI COVID-19 is a large-scale retrospective multicenter registry addressing in-hospital mortality, reperfusion, and 30-day mortality among primary PCI patients in the era of the COVID-19 pandemic. Among the 16,083 STEMI patients, 6819 (42.3%) patients were active smokers, 2099 (13.1%) previous smokers, and 7165 (44.6%) non-smokers. Despite the impaired preprocedural recanalization (p < 0.001), active smokers had a significantly better postprocedural TIMI flow compared with non-smokers (p < 0.001); this was confirmed after adjustment for all baseline and procedural confounders, and the propensity score. Active smokers had a significantly lower in-hospital (p < 0.001) and 30-day (p < 0.001) mortality compared with non-smokers and previous smokers; this was confirmed after adjustment for all baseline and procedural confounders, and the propensity score. In conclusion, in our population, active smoking was significantly associated with improved epicardial recanalization and lower in-hospital and 30-day mortality compared with previous and non-smoking history.

Association Between Initiation, Intensity, and Cessation of Smoking and Mortality Risk in Patients With Cardiovascular Disease: A Cohort Study

Objectives: To examine the effect of smoking status, smoking intensity, duration of smoking cessation and age of smoking initiation on the risk of all-cause and cause-specific mortality among cardiovascular disease (CVD) patients.

Design: A population-based prospective cohort study.

Setting: The National Health Interview Survey (NHIS) in the U.S. that were linked to the National Death Index (NDI).

Participants: 66,190 CVD participants ≥ 18 years of age who were interviewed between 1997 and 2013 in the NHIS linked to the NDI through December 31, 2015.

Outcome Measures: The primary outcome was all-cause mortality and the secondary outcome was cause-specific mortality including CVD mortality and cancer mortality.

Results: During the mean follow-up of 8.1 years, we documented 22,518 deaths (including 6,473 CVD deaths and 4,050 cancer deaths). In the overall CVD population, former and current smokers had higher risk of all-cause (Former smokers: hazard ratios (HRs), 1.26; 95% confidence interval (CI), 1.21–1.31, P < 0.001; Current smokers: HRs, 1.96; 95%CI, 1.86–2.07, P < 0.001), CVD (Former smokers: HRs, 1.12; 95%CI, 1.05–1.21, P = 0.001; Current smokers: HRs, 1.80; 95%CI, 1.64–1.97, P < 0.001) and cancer mortality (Former smokers: HRs, 1.49; 95%CI, 1.35–1.64, P < 0.001; Current smokers: HRs, 2.78; 95%CI, 2.49–3.09, P < 0.001) than never smokers. Furthermore, similar results were observed when the study subjects were stratified according to the type of CVD. Among current smokers, the risk for cancer mortality increased as the daily number of cigarettes increased, regardless of the specific type of CVD. However, the association of the risk for all-cause and CVD mortality with smoking intensity did not present a dose-response relationship. In participants with angina pectoris or stroke, smoking intensity was inversely associated with deaths from CVD. In addition, the risk for all-cause, CVD and cancer mortality declined as years of smoking cessation increased. Finally, the relative risk of all-cause mortality was not significantly different in individuals with a younger age of smoking initiation.

Conclusions: CVD patients who are smokers have an increased risk of all-cause, CVD and cancer mortality, and the risk decreases significantly after quitting smoking. These data further provide strong evidence that supports the recommendation to quit smoking for the prevention of premature deaths among individuals with CVD.

Bleeding Risk of Dual Antiplatelet Therapy after Minor Stroke or TIA

OBJECTIVE

To identify the risk of bleeding events and potential risk factors within 90 days in patients carried CYP2C19 loss-of-function alleles and received dual antiplatelet therapy after minor stroke or transient ischemic attack.

METHODS

A total of 6,412 patients were enrolled from the Clopidogrel with aspirin in High-risk patients with Acute Non-disabling Cerebrovascular Events II (CHANCE-2) trial. The main outcome was any bleeding within 90 days defined by the criteria from Global Utilisation of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO).

RESULTS

A total of 250 (3.9%) bleeding events were reported, which occurred mainly within the 21 days of dual antiplatelet therapy (200 cases, 3.1%). Minor bleeding of the skin bruises, epistaxis, and gum bleeding was most frequent. Multivariate analysis showed that treatment with ticagrelor-aspirin compared with clopidogrel-aspirin was associated with increased bleeding (hazard ratio [HR], 2.21; 95% confidence interval [CI], 1.68-2.89; P<0.001). Current smoking was associated with a lower risk of bleeding (HR, 0.70; 95% CI, 0.52-0.95; P=0.02). Additionally, ticagrelor-aspirin compared with clopidogrel-aspirin was associated with higher risk of bleeding in patients aged <65 years (HR, 2.87; 95% CI, 1.95-4.22) and those without diabetes mellitus (HR, 2.65; 95% CI, 1.88-3.73) (P for interaction=0.04 and 0.03, respectively).

INTERPRETATION

Bleeding events mostly occurred within the 21-day dual antiplatelet therapy stage and were generally mild. The risk of bleeding was greater in non-smoking patients, and was associated with treatment with ticagrelor-aspirin compared with clopidogrel-aspirin particularly in aged <65 years and non-diabetic patients. This article is protected by copyright. All rights reserved.

The Effect of Periprocedural Clinical Factors Related to the Course of STEMI in Men and Women Based on the National Registry of Invasive Cardiology Procedures (ORPKI) between 2014 and 2019

BACKGROUND

There are several sex-related differences in the course, management, and outcomes of ST-elevation myocardial infarction (STEMI). This study aimed to identify the risk factors that may affect the odds of procedure-related death in patients with STEMI.

METHODS

The observational cohort study group consisted of 118,601 participants recruited from the National Registry of Invasive Cardiology Procedures (ORPKI).

RESULTS

Procedure-related death occurred in 802 (1.0%) men and in 663 (1.7%) women. The odds of procedure-related death among women were significantly higher than among men (OR, 1.76; 95% CI, 1.59-1.95; p < 0.001). The probability of procedure-related mortality was highest in both men and women with cardiac arrest in the cath lab, critical stenosis of the left main coronary artery, and direct transfer to the cath lab. The factors that reduced the probability of procedure-related mortality in both men and women were thrombolysis in myocardial infarction (TIMI) flow grade and the use of P2Y12 inhibitors in the peri-infarct period. Psoriasis was associated with increased odds of procedure-related death among men, whereas cigarette smoking reduced the odds among women.

CONCLUSIONS

Procedure-related deaths occurred more frequently in women than men with STEMI. Additional scrutiny needs to be undertaken to identify factors influencing survival regarding gender differences.

P2Y12 receptor blockers are anti-inflammatory drugs inhibiting both circulating monocytes and macrophages including THP-1 cells

P₂Y₁₂ blockade improves patient outcomes after myocardial infarction. As well as antithrombotic effects, anti-inflammatory effects may contribute to this beneficial clinical outcome. Here we aimed to identify potential anti-inflammatory effects of P₂Y₁₂ receptor blockers on monocytes and macrophages. Using flow cytometry, migration assays, flow chambers and RNA microarrays, we investigated the effects of adenosine diphosphate (ADP) and P₂Y₁₂ receptor blockers on blood monocytes, THP-1 monocytes and THP-1 monocytes after differentiation to macrophages. P₂Y₁₂ -expressing platelets can form aggregates with monocytes in circulating blood. Mediated by platelets, ADP results in activation of the integrin receptor Mac-1 on blood monocytes, as detected by the conformation-specific single-chain antibody MAN-1. Via the same association with platelets, THP-1 monocyte adhesion to the endothelial intercellular adhesion molecule 1 (ICAM-1) is induced by ADP. P₂Y₁₂ receptor blockers prevent these ADP effects on monocytes. Interestingly, in contrast to THP-1 monocytes, THP-1 monocytes, after differentiation to macrophages, directly expressed the P₂Y₁₂ receptor and consequently ADP was found to be a potent chemoattractant. Again, P₂Y₁₂ receptor blockers antagonised this effect. Accordingly, stimulation of THP-1 macrophages with ADP caused a substantial change in gene expression pattern and upregulation of several genes associated with inflammation and atherogenesis. These data establish novel anti-inflammatory effects of P₂Y₁₂ receptor blockers on monocytes and macrophages, which are expected to contribute to cardiovascular risk reduction.

Efficacy and safety of ticagrelor versus prasugrel in smokers and nonsmokers with acute coronary syndromes

BACKGROUND

The efficacy and safety of ticagrelor versus prasugrel according to smoking status in patients with acute coronary syndromes (ACS) are not known. We assessed the efficacy and safety of ticagrelor versus prasugrel according to smoking status in patients with ACS undergoing invasive management.

METHODS

This pre-specified analysis of the ISAR-REACT 5 trial included 1349 smokers and 2652 nonsmokers randomized to receive ticagrelor or prasugrel. The primary endpoint was the incidence of death, myocardial infarction, or stroke; the secondary endpoint was the incidence of Bleeding Academic Research Consortium (BARC) type 3 to 5 bleeding (both endpoints assessed at 12 months).

RESULTS

There was no significant treatment arm-by-smoking status interaction regarding the efficacy outcome. The primary endpoint occurred in 47 patients (7.0%) in the ticagrelor group and 41 patients (6.2%) in the prasugrel group in smokers (hazard ratio [HR] = 1.15; 95% confidence interval [CI] 0.76-1.75; P = 0.510) and in 133 patients (10.2%) in the ticagrelor group and 94 patients (7.2%) in the prasugrel group in nonsmokers (HR = 1.44 [1.10-1.87]; P = 0.007; P for interaction = 0.378). The secondary endpoint occurred in 27 patients (4.6%) in the ticagrelor group and 33 patients (5.6%) in the prasugrel group in smokers (HR = 0.81 [0.49-1.35]; P = 0.412) and in 66 patients (6.0%) in the ticagrelor group and 46 patients (4.4%) in the prasugrel group in nonsmokers (HR = 1.38 [0.94-2.01]; P = 0.097).

CONCLUSIONS

In patients with ACS undergoing an invasive management strategy, the smoking status did not significantly interact with the relative treatment effect of ticagrelor vs. prasugrel.

CLINICAL TRIAL REGISTRATION

NCT01944800.

The Future of Aspirin Therapy in Cardiovascular Disease

Much has been written about the demise of aspirin (ASA) but reports of its death are premature. The drug remains one of the most widely prescribed by physicians worldwide. It is cheap, familiar, and effective for a variety of uses, including in patients with acute or prior myocardial infarction, ischemic stroke, peripheral artery disease, and percutaneous or surgical revascularization procedures, as well as for use for pain and fever relief. Beyond physician prescription or recommendation, over the counter use of ASA is common, including for primary cardiovascular prevention, though this decision really should involve a discussion of risks and benefits with a physician. ASA is an essential member of the duo that makes up dual antiplatelet therapy (a P2Y₁₂ inhibitor plus ASA) and also dual pathway inhibition (vascular dose rivaroxaban plus ASA), and data for both approaches are growing. Furthermore, research is ongoing as to the optimal dosing frequency (once vs twice daily), potentially safer gastrointestinal delivery, and possibly more effective formulations in terms of platelet inhibition. One goal of ASA research is to try to reduce bleeding complications that are a risk with all anti-thrombotic therapies. Although its exact roles will continue to evolve, the future for ASA remains bright.

Influences of Smoking Status on Effectiveness of Cytochrome P450 Enzyme System Metabolized Medications in Reducing In-Hospital Death in 14 658 Patients With Acute Myocardial Infarction: Data From CPACS-3 Study

BACKGROUND

The benefit of cytochrome P450 (CYP450) enzyme system metabolized medications, especially clopidogrel, was reported more pronounced in smoking than nonsmoking patients, but limited evidence was available from Asian patients. We analyzed data from a large registry-based study of Chinese patients with acute myocardial infarction (AMI) to understand if the above finding could be reproduced.

METHODS

A total of 14 658 patients with AMI were prospectively recruited from 101 hospitals across China. Generalized estimating equation was applied to assess the association between CYP450 enzyme system metabolized medications (clopidogrel, statins, calcium channel blockers) and in-hospital death in smoking and nonsmoking patients, separately, adjusting for hospital clustering effects and propensity score of using the medication in question.

RESULTS

There were 86%, 93%, and 10% of study patients who received clopidogrel, statins, and calcium channel blockers during the hospitalization. Compared with patients not receiving clopidogrel, patients receiving the drug had a significantly lower risk of in-hospital death (adjusted relative risk [RR] = 0.61, 95% confidence interval [CI]: 0.40-0.91) in current smokers but an insignificant lower risk (adjusted RR = 0.85, 95% CI: 0.71-1.01) in nonsmokers, and the P for interaction was <.01. The corresponding adjusted RR was 0.45 (95% CI: 0.24-0.86) in current smokers and 0.94 (95% CI: 0.68-1.29) in nonsmokers (P for interaction <.01) for statins use and 1.00 (95% CI: 0.53-1.89) in current smokers and 0.66 (95% CI: 0.48-0.90) in nonsmokers (P for interaction = .23) for calcium channel blockers use.

CONCLUSIONS

Our study in a large cohort of Chinese patients with AMI found that the treatment effect in reducing risk of in-hospital death was significantly larger in smokers than in nonsmokers as for clopidogrel and statins but not for calcium channel blockers.

Polyvascular disease in patients with myocardial infarction and chronic kidney disease

Aim. To study polyvascular disease in patients with myocardial infarction (MI) and chronic kidney disease (CKD). Materials and methods. A total of 954 patients older than 18 years old with ST-segment elevation MI (STEMI) up to 24 hours of pain onset were included in the study. Clinical and demographic data were collected for all patients, including physical examination, 16-lead electrocardiogram recording, echocardiography, laboratory assessment with the measurements of cardiospecific enzymes and serum creatinine. Glomerular filtration rate (GFR) was estimated according to the CKD-EPI equation. Of them, 771 (81%) underwent coronary angiography, duplex scanning of the brachiocephalic (BCA) and lower extremity arteries (LEA). Patients with stage 1-4 CKD diagnosed according to the criteria provided by the Russian Society of Nephrologists were allocated into a separate group (n=281; 36.5%). CKD stages were determined with the level of GFR. Patients with stage 5 CKD were excluded from the study. Renal dysfunction was defined as the presence of an estimated GFR less than 60 ml/min/1.73 m2. Results and discussion. The results of the study indicate a high prevalence of PolyVD in patients with CKD. Every second patient had LEA stenosis (p

Effectiveness and Safety of Platelet ADP -P2Y12 Receptor Inhibitors Influenced by Smoking Status: A Systematic Review and Meta-Analysis

Background As reports on the influence of cigarette smoking, an important cardiovascular risk factor, on platelet ADP -P2Y12 receptor inhibitors lack consistency, we aimed to assess the effectiveness and safety of platelet ADP -P2Y12 receptor inhibitors influenced by smoking status. Methods and Results PubMed, Web of Science, EMBASE , Clinical Trials, and the Cochrane Library were searched from inception until June 2018. Among the 5076 citations retrieved, 22 studies, including 163 011 patients with or without percutaneous coronary intervention, were included for meta-analysis. Compared with nonsmokers within the first year of follow-up, the reductions of stroke and major adverse cardiovascular event rate were 18% ( P=0.008) and 26% ( P=0.02), respectively. A 20% reduction in stroke ( P=0.02) and a 34% reduction in major adverse cardiovascular event ( P=0.0001) rates were observed in smoking patients without percutaneous coronary intervention. No significant difference was observed in clinical outcome rates among prasugrel, ticagrelor, and clopidogrel in different smoking status. No significant difference was found in myocardial infarction and bleeding event incidence between current smokers and nonsmokers. Conclusions We concluded that current smokers had a lower incidence of major adverse cardiovascular events and stroke events than did nonsmokers, particularly in the early period (1 year) and among patients without percutaneous coronary intervention. However, because of the lack of original adjusted data, smoker's paradox still needs to consider the impact of age and other covariates. Thus, a differential risk-benefit evaluation should be considered, according to different smoking status, patient conditions, and therapy time points.

The effect of smoking on residual platelet reactivity to clopidogrel: a systematic review and meta-analysis

Cigarette smoking is an important cardiovascular risk factor, causing morbidity and mortality. There are many original studies on the impact of smoking, but its influence on platelet ADP-P2Y12 receptor inhibitors lack consistency. Thus, we conducted a systematic review and meta-analysis of already existing data/studies to further explore this issue. PubMed, Web of science, EMBASE, Clinical Trials, and the Cochrane Library were searched from inception to March 2018. Studies investigating the residual platelet reactivity categorized by smoking status and patients treated with platelet ADP-P2Y12 receptor inhibitors qualified the inclusion criteria. The primary outcome was P2Y12 reaction unit (PRU) value measured by VerifyNow P2Y12 assay, compared with different smoking status in ADP-P2Y12 receptor inhibitors treatment groups. Secondary outcome was post-treatment with 5 μmol/L ADP-inhibition of platelet aggregation (ADP-IPA) measured by light transmittance aggregometry (LTA). Of the 4954 citations retrieved, 12 studies involving 16 296 patients with acute coronary syndrome and/or stent deployment using platelet ADP-P2Y12 receptor inhibitors were included for meta-analysis. Pooled analysis revealed that PRU values of current smokers were 25.70 lower than nonsmokers (95% CI -38.81 to -12.60, p = 0.0001), getting better effects of antiplatelet treatment. In the smoking extent subgroup analysis, patients smoking >10 cigarettes/day shown about 46.49 lower of PRU values than patients smoking <10 cigarettes/day (p < 0.00001). Racial subgroup analyses found that smokers had increased platelet inhibition in the Caucasian population. Further, pooled analysis of ADP-IPA values for 1658 patients from five studies showed a significantly lower residual platelet reactivity in current smokers compared to that in nonsmokers (MD = -4.19; 95% CI -6.55 to -1.83; p = 0.0005). This systematic review and meta-analysis suggested that smokers have increased platelet inhibition and lower aggregation in response to clopidogrel than nonsmokers. These residual platelet reactivity observations may help to explain differential clinical outcomes in smokers vs. nonsmokers in large scale clinical trials.

Medical Resource Consumption and Quality of Life in Peripheral Arterial Disease in Korea: PAD Outcomes (PADO) Research

BACKGROUND AND OBJECTIVES

We aimed to investigate the history of medical resource consumption and quality of life (QoL) in peripheral arterial disease (PAD) patients in Korea.

METHODS

This was a prospective, multi-center (23 tertiary-hospitals, division of cardiology), non-interventional study. Adult patients (age ≥20 years) suffering from PAD for the last 12-month were enrolled in the study if they met with any of following; 1) ankle-brachial index (ABI) ≤0.9, 2) lower-extremity artery stenosis on computed tomography angiography ≥50%, or 3) peak-systolic-velocity-ratio (PSVR) on ultrasound ≥2.0. Medical chart review was used to assess patient characteristics/treatment patterns while the history of medical resource consumption and QoL data were collected using a patient survey. QoL was measured using EuroQoL-5-dimensions-3-level (EQ-5D-3L) score system, and the factors associated with QoL were analyzed using multiple linear regression analysis.

RESULTS

This study included 1,260 patients (age: 69.8 years, male: 77.0%). The most prevalent comorbidities were hypertension (74.8%), hyperlipidemia (51.0%) and diabetes-mellitus (50.2%). The 94.1% of the patients took pharmacotherapy including aspirin (76.2%), clopidogrel (53.3%), and cilostazol (33.6%). The 12.6% of the patients were receiving smoking cessation education/pharmacotherapy. A considerable number of patients (500 patients, 40.0%) had visit history to another hospital before diagnosis/treatment at the current hospital, with visits to orthopedic units (50.4%) being the most common. At the time, 29% (or higher) of the patients were already experiencing symptoms of critical limb ischemia. Baseline EQ-5D index and EQ VAS were 0.64±0.24 and 67.49±18.29. Factors significantly associated with QoL were pharmacotherapy (B=0.05053; p=0.044) compared to no pharmacotherapy, and Fontaine stage improvement/maintain stage I (B=0.04448; p<0.001) compared to deterioration/maintain stage II-IV.

CONCLUSIONS

Increase in disease awareness for earlier diagnosis and provision of adequate pharmacotherapy is essential to reduce disease burden and improve QoL of Korean PAD patients.

Cardiovascular risk reduction in referrals to outpatient vascular clinics

Introduction

Patients with peripheral arterial disease (PAD), aneurysmal disease (AD) or carotid atherosclerosis are at high cardiovascular risk, necessitating secondary cardiovascular protection. The aim of this study was to determine compliance with cardiovascular risk reduction guidelines in new patients referred to vascular clinics.

Methods

A multicentre collaborative national observational audit of new patients referred to eight tertiary general vascular clinics over a three-month period in England and Wales was conducted by the Vascular and Endovascular Research Network (VERN). Referral letters, case notes and investigations were reviewed by local investigators, and data analysed by VERN.

Results

A total of 656 patients were included in the study: 73.2% had PAD, 23.2% had AD and 3.7% had carotid atherosclerosis. A third (37.5%) were current smokers, two-thirds (61.7%) were on antiplatelet therapy and two-thirds (61.5%) were on statin therapy. Smoking was more prevalent in the PAD cohort (PAD 41.4%, AD 27.5%, p =0.003). However, more PAD patients were on antiplatelet therapy (PAD 63.9%, AD 53.3%, p =0.024). Both antiplatelet and statin prescription significantly increased with the number of cardiovascular risk factors. Patients with a previous cardiac or cerebrovascular history were more likely to have stopped smoking, and to be on antiplatelet and statin therapy (p <0.0001 for each). Overall, 47.3% of patients were on both antiplatelet and statin therapy, and 28.9% were on antiplatelet and statin therapy and not smoking.

Conclusions

This study highlights deficiencies in cardiovascular risk minimisation in patients with established vascular disease. Patients with concomitant cardiac or cerebrovascular disease were more likely to be on best medical therapy.

Double-Dose Versus Standard-Dose Clopidogrel According to Smoking Status Among Patients With Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention

Background

Prior Studies have suggested better outcomes in smokers compared with nonsmokers receiving clopidogrel (“smoker's paradox”). The impact of a more intensive clopidogrel regimen on ischemic and bleeding risks in smokers with acute coronary syndromes requiring percutaneous coronary interventions remains unclear.

Methods and Results

We analyzed 17 263 acute coronary syndrome patients undergoing percutaneous coronary intervention from the CURRENT‐OASIS 7 (Clopidogrel and Aspirin Optimal Dose Usage to Reduce Recurrent Events—Seventh Organization to Assess Strategies in Ischemic Symptoms) trial, which compared double‐dose (600 mg day 1;150 mg days 2–7; then 75 mg daily) versus standard‐dose (300 mg day 1; then 75 mg daily) clopidogrel in acute coronary syndrome patients. The primary outcome was cardiovascular death, myocardial infarction, or stroke at 30 days. Interactions between treatment allocation and smoking status (current smokers versus nonsmokers) were evaluated. Overall, 6394 patients (37.0%) were current smokers. For the comparison of double‐ versus standard‐dose clopidogrel, there were significant interactions in smokers and nonsmokers for the primary outcome (P=0.031) and major bleeding (P=0.002). Double‐ versus standard‐dose clopidogrel reduced the primary outcome among smokers by 34% (hazard ratio [HR] 0.66, 95% confidence interval [CI], 0.50–0.87, P=0.003), whereas in nonsmokers, there was no apparent benefit (HR 0.96, 95% CI, 0.80–1.14, P=0.61). For major bleeding, there was no difference between the groups in smokers (HR 0.77, 95% CI, 0.48–1.24, P=0.28), whereas in nonsmokers, the double‐dose clopidogrel regimen increased bleeding (HR 1.89, 95% CI, 1.37–2.60, P<0.0001). Double‐dose clopidogrel reduced the incidence of definite stent thrombosis in smokers (HR 0.41, 95% CI, 0.24–0.71) and nonsmokers (HR 0.63, 95% CI, 0.42–0.93; P for interaction=0.19).

Conclusions

In smokers, a double‐dose clopidogrel regimen reduced major cardiovascular events and stent thrombosis after percutaneous coronary intervention, with no increase in major bleeding. This suggests that clopidogrel dosing in patients with acute coronary syndromes should be personalized, taking into consideration both ischemic and bleeding risk.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00335452.

Discordance Between VASP Phosphorylation and Platelet Aggregation in Defining High On-Clopidogrel Platelet Reactivity After ST-Segment Elevation Myocardial Infarction

To investigate potential clinical characteristics associated with discordance between platelet vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) flow cytometry (FCM) assay and light transmission aggregometry (LTA) in defining high on-clopidogrel platelet reactivity (HPR) after ST-segment elevation myocardial infarction (STEMI). In this study, platelet responsiveness was measured by the above 2 methods simultaneously on day 1 and on day 6 of STEMI onset in 90 consecutive patients who underwent primary percutaneous coronary intervention. The FCM-derived platelet reactivity index and LTA-derived platelet aggregation rate were both significantly reduced after dual antiplatelet therapy on day 6. Multiple variable-adjusted logistic regression analysis revealed that smoking (odds ratio [OR]: 4.507, 95% confidence interval [CI]: 1.123-18.09, P = .034) and onset-to-admission time (per 1 hour increase, OR: 1.196, 95% CI: 1.023-1.398, P = .025) both were independent predictors for the discordance between the 2 methods. Additionally, improved correlation and concordance was observed in nonsmokers compared with smokers. Our data show that smoking and prolonged onset-to-admission time are associated with discordance between platelet VASP-P and LTA in defining HPR after STEMI, which should be considered when planning personalized antiplatelet therapy.

Pharmacokinetic and Pharmacodynamic Responses to Clopidogrel: Evidences and Perspectives

Clopidogrel has significantly reduced the incidence of recurrent atherothrombotic events in patients with acute coronary syndrome (ACS) and in those undergoing percutaneous coronary intervention (PCI). However, recurrence events still remain, which may be partly due to inadequate platelet inhibition by standard clopidogrel therapy. Genetic polymorphisms involved in clopidogrel’s absorption, metabolism, and the P2Y12 receptor may interfere with its antiplatelet activity. Recent evidence indicated that epigenetic modification may also affect clopidogrel response. In addition, non-genetic factors such as demographics, disease complications, and drug-drug interactions can impair the antiplatelet effect of clopidogrel. The identification of factors contributing to the variation in clopidogrel response is needed to improve platelet inhibition and to reduce risk for cardiovascular events. This review encompasses the most recent updates on factors influencing pharmacokinetic and pharmacodynamic responses to clopidogrel.

Antiplatelet Strategies and Outcomes in Patients with Noncardioembolic Ischemic Stroke from a Real-World Study with a Five-Year Follow-Up

Aspirin and clopidogrel are both acceptable antiplatelet options for the secondary prevention of noncardioembolic ischemic stroke. Associations between Essen Stroke Risk Score (ESRS) and antiplatelet treatment in Chinese patients with noncardioembolic ischemic stroke were assessed. This retrospective study was taken in a tertiary care hospital located in eastern China. Patients with noncardioembolic ischemic stroke hospitalized during January 1, 2009, to December 31, 2011, were classified according to ESRS during index stroke hospitalization. Antiplatelet strategy at the time of discharge was categorized as aspirin (100 mg/day) vs. clopidogrel (75 mg/day). Patients received follow-up from July 1, 2014, to December 31, 2015, and the efficacy of clopidogrel and aspirin in different ESRS subgroups was assessed with respect to reducing the risk of a combined vascular event of recurrent stroke, myocardial infarction, or primary intracranial hemorrhage. Totally, 1175 non-cardiac stroke patients were included, among which 878 patients completed follow-up surveys. Of the patients who completed the follow-up, 458 (52.2%) had an ESRS > 3, and 621 (70.7%) received aspirin. Patients who received clopidogrel tended to be older, and more patients had hypertension, diabetes, and an ESRS > 3 than patients who received aspirin. Over a mean follow-up of 5.2 years, the rate of combined vascular events was 19.3% in the aspirin group and 16.7% in the clopidogrel group. Compared with clopidogrel-treated patients, a significant (P = 0.044) reduction in combined vascular events in aspirin-treated patients was observed in patients with an ESRS ≤ 3 (OR, odds ratio 0.5; 95% CI 0.3 to 0.9). However, a significant (P = 0.002) increase in combined vascular events was observed in patients with an ESRS > 3 (OR 2.2; 95% CI 1.3 to 3.8). More clopidogrel-treated patients with ESRS < 3 and ESRS = 3 discontinued treatment than their counterparts who took aspirin (P < 0.05). Adverse drug events, such as digestive discomfort and bleeding, were similar. In conclusion, clopidogrel is suggested for patients with an ESRS > 3 and aspirin for patients with an ESRS ≤ 3 for the secondary prevention of noncardioembolic ischemic stroke in Chinese patients.

Clopidogrel and ischemic stroke outcomes by smoking status: Smoker's paradox?

BACKGROUND AND PURPOSE

Active smokers with myocardial infarction were shown to have enhanced benefit with clopidogrel compared with aspirin. Whether this "paradox" exists in ischemic stroke patients is unknown. We aimed to investigate whether smoking status has a differential impact on the efficacy of clopidogrel vs. aspirin in patients with non-cardioembolic strokes.

METHODS

This single-center study retrospectively assessed 1792 non-cardioembolic ischemic stroke patients discharged from January 2013 to October 2014, and followed for 12months. Patients were categorized as current-smokers and never-smokers. Primary outcome was a composite of secondary ischemic stroke, myocardial infarction and all-cause death. Secondary outcome was secondary ischemic stroke.

RESULTS

1066 patients were current-smokers and 726 were never-smokers. Compared with never-smokers, current-smokers had significantly higher rates of ischemic stroke (4.3% vs. 1.2%; adjusted OR: 3.60, 95%CI: 1.50-8.64, p=0.004). Regarding the primary outcome, among smokers, rates showed a lower trend in clopidogrel vs. aspirin groups (3.7% vs. 6.4%; adjusted OR 0.57, 95%CI: 0.31-1.07, p=0.08), but no difference among never-smokers (2.1% vs. 1.0%; adjusted OR: 1.67, 95%CI: 0.47-5.89, p=0.42). Similarly, among smokers, trending lower rates for recurrent ischemic stroke were observed in clopidogrel vs. aspirin group (3.1% vs. 5.0%; adjusted OR: 0.60, 95%CI: 0.31-1.18, p=0.14); but no difference between the two groups among never-smokers (1.7% vs. 1.0%; adjusted OR 1.36, 95%CI: 0.36-5.52, p=0.65).

CONCLUSIONS

Smoking is a major risk factor for recurrent stroke in our retrospective non-cardioembolic ischemic stroke cohort. Active-smokers trend toward better cardiovascular outcomes when on clopidogrel. This finding needs to be confirmed in a prospective cohort.

Prognostic Factors in Patients With Stemi Undergoing Primary PCI in the Clopidogrel Era: Role of Dual Antiplatelet Therapy at Admission and the Smoking Paradox on Long-Term Outcome

BACKGROUND

Several clinical and laboratory variables have an impact on the prognosis of STEMI patients undergoing PPCI; however, little is known about the role of ongoing DAPT at the time of the event and the smoking status as prognostic factors affecting the outcome of these patients.

METHODS AND RESULTS

Seven-hundred and thirteen consecutive STEMI patients undergoing PPCI, admitted to the S. Anna and S. Sebastiano Hospital (Caserta, Italy) and to the OLV Clinic (Aalst, Belgium), between March 2009 and December 2011, were retrospectively enrolled. Rescue PCI was the only exclusion criterion. Primary end-point was the combination of death for all causes, re-infarction, stroke, and target lesion revascularization (TLR). Patients already on DAPT at admission (26.4%) showed a significant increase in the event rate at univariate analysis (HR 2.34, CI 1.62-3.75, P < 0.05), while current smokers (56.5%) had a lower event rate, as compared to non-smokers (HR 0.67, CI 0.46-0.96, P < 0.05). In smoking patients already on DAPT at admission, a lower event rate was observed than in non-smoking patients on DAPT. Although, patients already on DAPT had a higher-risk profile (renal impairment, ongoing statin treatment, ST resolution <50%, and Killip class >1 were more frequently present than in patients not on DAPT), Cox regression analysis confirmed that both DAPT (HR 1.74, 95%CI 1.20-2.53, P < 0.01) and smoking status (HR 0.69, 95%CI 0.48-1.00, P < 0.05) retained their statistical significance, as they and were significantly associated with a worse and a better outcome, respectively, underlying their role as independent prognostic factors.

CONCLUSIONS

Not being a current smoker and ongoing DAPT at admission, in patients with STEMI undergoing PPCI, represent independent negative prognostic value.

Smoker's Paradox in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

BACKGROUND

Prior studies have found that smokers undergoing thrombolytic therapy for ST-segment elevation myocardial infarction have lower in-hospital mortality than nonsmokers, a phenomenon called the "smoker's paradox." Evidence, however, has been conflicting regarding whether this paradoxical association persists in the era of primary percutaneous coronary intervention.

METHODS AND RESULTS

We used the 2003-2012 National Inpatient Sample databases to identify all patients aged ≥18 years who underwent primary percutaneous coronary intervention for ST-segment elevation myocardial infarction. Multivariable logistic regression was used to compare in-hospital mortality between smokers (current and former) and nonsmokers. Of the 985 174 patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention, 438 954 (44.6%) were smokers. Smokers were younger, were more often men, and were less likely to have traditional vascular risk factors than nonsmokers. Smokers had lower observed in-hospital mortality compared with nonsmokers (2.0% versus 5.9%; unadjusted odds ratio 0.32, 95% CI 0.31-0.33, P<0.001). Although the association between smoking and lower in-hospital mortality was partly attenuated after baseline risk adjustment, a significant residual association remained (adjusted odds ratio 0.60, 95% CI 0.58-0.62, P<0.001). This association largely persisted in age-stratified analyses. Smoking status was also associated with shorter average length of stay (3.5 versus 4.5 days, P<0.001) and lower incidence of postprocedure hemorrhage (4.2% versus 6.1%; adjusted odds ratio 0.81, 95% CI 0.80-0.83, P<0.001) and in-hospital cardiac arrest (1.3% versus 2.1%; adjusted OR 0.78, 95% CI 0.76-0.81, P<0.001).

CONCLUSIONS

In this nationwide cohort of patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction, we observed significantly lower risk-adjusted in-hospital mortality in smokers, suggesting that the smoker's paradox also applies to ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention.

Effect of clinical factors and gene polymorphism of CYP2C19*2, *17 and CYP4F2*3 on early stent thrombosis

Aim: To determine the main clinical and genetic factors having impact on early coronary stent thrombosis. Materials & methods: Genotyping of CYP2C19*2, *17 and CYP4F2*3 in patients with (n = 31) and without stent thrombosis (n = 456) was performed. Clinical and genetic data were analyzed by binary logistic regression. Results: Smoking (OR: 0.317; 95% CI: 0.131–0.767), high-density lipoprotein level in mmol/l (OR: 0.142; 95% CI: 0.040–0.506), CYP2C19*2*2 versus *1*1 and *1*2 genotype (OR: 11.625; 95% CI: 3.498–38.633), CYP4F2 AA versus GA and GG genotype (OR: 3.532; 95% CI: 1.153–10.822) were associated with early stent thrombosis. Conclusion: For the first time we have identified a clinically important polymorphism (CYP4F2 G1347A) that was independently associated with early stent thrombosis.

Original submitted 18 August 2014; Revision submitted 10 November 2014

Update: Acute coronary syndromes (IX). Secondary prevention strategies for acute coronary syndrome

Cardiovascular disease is the main health problem in Europe and the rest of the world and is the leading cause of death and health care expenditure. By reducing mortality and ischemic event recurrence, prevention strategies play a fundamental role in patients who have had an acute coronary syndrome. Although these prevention strategies have focused with great success on high-risk individuals, they should also be used in the general population, which is showing an increase in the prevalence of obesity, diabetes mellitus, and other comorbidities that may reverse this trend toward reduced mortality. The present article consists of an up-to-date review of the main cardiovascular prevention measures, particularly the new developments of the last year, as well as the particularities of these measures when they are targeted at patients with a prior acute coronary syndrome.

Impact of smoking status on platelet function and clinical outcomes with prasugrel vs. clopidogrel in patients with acute coronary syndromes managed without revascularization: Insights from the TRILOGY ACS trial

BACKGROUND

To further explore the impact of smoking on antiplatelet activity and treatment response, we evaluated time-dependent relationships between smoking status with on-treatment platelet reactivity and clinical outcomes for prasugrel vs. clopidogrel in patients with acute coronary syndromes managed medically without revascularization.

METHODS AND RESULTS

A total of 7062 patients aged <75 years from the primary TRILOGY ACS cohort randomized to prasugrel vs. clopidogrel were evaluated through 30 months by baseline and time-dependent smoking status with adjusted proportional-hazards models. A total of 1994 participants (28%) [corrected] were included in a platelet function sub-study evaluating serial P2Y12 reaction unit (PRU) measurements. Current smokers (n = 1566 [22%]) at baseline had fewer comorbidities compared with non-smokers; nearly half quit smoking during follow-up. Although median on-treatment PRU values were lower with prasugrel vs. clopidogrel, persistent smokers had lower serial PRU values in both treatment groups compared with non-smokers, with no differential interaction of treatment response by smoking status. The frequency of cardiovascular death, myocardial infarction, or stroke in current smokers was significantly lower with prasugrel (11.7%) vs. clopidogrel (18.6%), but there was no difference in non-smokers (13.8% vs. 13.7%), with significant interaction between treatment and baseline smoking status (P = .0002). Bleeding events occurred more frequently in prasugrel-treated patients with no significant interaction between treatment and baseline smoking status.

CONCLUSIONS

Among medically managed ACS patients <75 years of age, the risk of ischemic outcomes was significantly reduced with prasugrel vs. clopidogrel among smokers vs. non-smokers. No interaction between on-treatment platelet reactivity and smoking status was found.

Levels and values of lipoprotein-associated phospholipase A2, galectin-3, RhoA/ROCK, and endothelial progenitor cells in critical limb ischemia: pharmaco-therapeutic role of cilostazol and clopidogrel combination therapy

Objective

We tested the hypothesis that clopidogrel and cilostazol combination therapy could effectively attenuate systemic inflammatory reaction, facilitate proliferation of circulating endothelial progenitor cell (EPC), and improve the clinical outcomes of critical limb ischemia (CLI) in patients unsuitable for surgical revascularization or percutaneous transluminal angioplasty (PTA).

Methods

A total 55 patients (mean age, 72 years; 56% female) were consecutively enrolled. Clopidogrel and cilostazol combination therapy was administered throughout the study period.

Results

As compared with the baseline, circulating endothelial progenitor cell level (as shown by flow cytometry) was significantly increased (p < 0.003), whereas the CLI-related ulcers and painfulness were significantly improved (all p < 0.01) by day 90 after treatment. On the other hand, after clopidogrel and cilostazol combination therapy, galectin-3 level, lipoprotein-associated phospholipase A₂ gene expression, and RhoA/ROCK-related protein expression in peripheral blood mononuclear cells were significantly suppressed (all p < 0.01). Eventually, by day 90, 5 patients (9.1%) died of other etiologies, 3 (5.5%) withdrew from the study, 6 (10.9%) required amputation, and the remaining 41 had satisfactory clinical improvement with complete wound healing in 9 (16.4%) patients.

Conclusion

The results of the present study highlight that clopidogrel and cilostazol combination therapy may be considered to be an alternative method for treating patients with CLI unsuitable for surgical revascularization or PTA.

Effect of smoking on comparative efficacy of antiplatelet agents: systematic review, meta-analysis, and indirect comparison

OBJECTIVE

To evaluate whether smoking status is associated with the efficacy of antiplatelet treatment in the prevention of cardiovascular events.

DESIGN

Systematic review, meta-analysis, and indirect comparisons.

DATA SOURCES

Medline (1966 to present) and Embase (1974 to present), with supplementary searches in databases of abstracts from major cardiology conferences, the Cumulative Index to Nursing and Allied Health (CINAHL) and the CAB Abstracts databases, and Google Scholar.

STUDY SELECTION

Randomized trials of clopidogrel, prasugrel, or ticagrelor that examined clinical outcomes among subgroups of smokers and nonsmokers.

DATA EXTRACTION

Two authors independently extracted all data, including information on the patient populations included in the trials, treatment types and doses, definitions of clinical outcomes and duration of follow-up, definitions of smoking subgroups and number of patients in each group, and effect estimates and 95% confidence intervals for each smoking status subgroup.

RESULTS

Of nine eligible randomized trials, one investigated clopidogrel compared with aspirin, four investigated clopidogrel plus aspirin compared with aspirin alone, and one investigated double dose compared with standard dose clopidogrel; these trials include 74,489 patients, of whom 21,717 (29%) were smokers. Among smokers, patients randomized to clopidogrel experienced a 25% reduction in the primary composite clinical outcome of cardiovascular death, myocardial infarction, and stroke compared with patients in the control groups (relative risk 0.75, 95% confidence interval 0.67 to 0.83). In nonsmokers, however, clopidogrel produced just an 8% reduction in the composite outcome (0.92, 0.87 to 0.98). Two studies investigated prasugrel plus aspirin compared with clopidogrel plus aspirin, and one study investigated ticagrelor plus aspirin compared with clopidogrel plus aspirin. In smokers, the relative risk was 0.71 (0.61 to 0.82) for prasugrel compared with clopidogrel and 0.83 (0.68 to 1.00) for ticagrelor compared with clopidogrel. Corresponding relative risks were 0.92 (0.83 to 1.01) and 0.89 (0.79 to 1.00) among nonsmokers.

CONCLUSIONS

In randomized clinical trials of antiplatelet drugs, the reported clinical benefit of clopidogrel in reducing cardiovascular death, myocardial infarction, and stroke was seen primarily in smokers, with little benefit in nonsmokers.