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

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.

The DNAm levels of CREB5 (cg11301281) were associated with clopidogrel resistance

Purpose

Clopidogrel resistance (CR) is mostly caused by interindividual variability of the platelet inhibition of clopidogrel, which may induce cardiovascular events. The aim of this research was to evaluate whether DNAm levels of CREB5 (cg01534253) are involved in CR among acute coronary syndrome (ACS) patients treated with clopidogrel.

Methods

72 patients(36 CR and 36 non‐CR) who underwent ACS were included in this study. The VerifyNow P2Y12 assay was selected to evaluate residual platelet reactivity, and bisulfite pyrosequencing methods was used to examine DNA methylation levels on cg01534253. Secondly, CREB5 mRNA expression was analyzed via quantitative real‐time PCR. Last, we employed logistic regression to test the interaction between genetic factors of CREB5 methylation and multiple clinical variables in CR patients.

Results

Subunit analysis indicated that for patients whose HbA1c levels were ≥6.5% or whose GLU levels were ≥7 mmol/L, lower methylation of cg01534253 indicated a poorer clopidogrel response. In addition, CREB5 mRNA expression was increased in CR patients with GLU levels ≥7 mmol/L. Moreover, regression analysis indicated that the values of albumin and uric acid were correlated with the incidence of CR.

Conclusions

Our findings were likely to provide fresh understanding for the new mechanism of platelet inhibition failure and promote individualized antiplatelet therapy.

No Paradoxical Effect of Smoking Status on Recurrent Cardiovascular Events in Patients Following Percutaneous Coronary Intervention: Thai PCI Registry

Background

"Smoker's paradox" is a controversial phenomenon that describes an unexpectedly favorable short-term outcome of smokers post-percutaneous coronary intervention (PCI). This study aimed to evaluate the effect of smoking status on recurrent major adverse cardiovascular events (MACEs) in patients who recently underwent PCI and to determine whether it was paradoxical.

Methods

This study utilized data from the nationwide Thai PCI registry, enrolling patients during 2018-2019. Our study factor was smoking status, classified as current smokers, ex-smokers, and nonsmokers. The outcome of interest was the time to occurrence of a composite of MACEs (i.e., all-cause death, myocardial infarction (MI), stroke, and unplanned revascularization) evaluated at about 1-year post-PCI. A propensity score (PS) model using inverse probability weighting with regression adjustment was used to estimate the effect of smoking on the occurrence of MACE.

Results

Current smokers, ex-smokers, and non-smokers accounted for 23, 32, and 45% of the 22,741 subjects, respectively. Smokers were younger, more frequently male, and had fewer traditional atherosclerotic risk factors. Current smokers presented more frequently with ST-elevation MIs (STEMIs) and cardiogenic shock (54 and 14.6%, respectively) than non-smokers. MACE rates were 1.9, 1.2, and 1.6 per 100 patients per month in the current smokers, ex-smokers, and non-smokers, respectively. After applying a PS, patients with a history of current smoking and ex-smoking developed the onset of recurrent MACEs significantly sooner than non-smokers, with a median time of 4.4 vs. 4.9 vs. 13.5 months (p < 0.001), respectively.

Conclusions

"Smoker's paradox" was not observed in our patient population. Current smokers and ex-smokers were prone to develop an earlier onset of a post-PCI MACEs than nonsmokers and need a smoke cessation program for further prevention.

Impact of smoking on all-cause mortality and cardiovascular events in patients after coronary revascularization with a percutaneous coronary intervention or coronary artery bypass graft: a systematic review and meta-analysis

Although cigarette smoking is an independent risk factor for cardiovascular disease, inconsistent results have been published in the literature on its impacts on the cardiovascular health of patients after coronary revascularization with a percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG). We performed a comprehensive electronic database search through July 2018. Studies reporting the risk estimates of all-cause mortality and cardiovascular outcomes in patients after coronary revascularization with PCI or CABG on the basis of smoking status were selected. Multivariate-adjusted relative risks (RRs) and 95% confidence intervals (CIs) were pooled using random-effects models with inverse variance weighting. Data from 37 records including 126 901 participants were finally collected. Overall, the pooled RR (95% CI) associated with cigarette smoking was 1.26 (95% CI: 1.09-1.47) for all-cause mortality, 1.08 (95% CI: 0.92-1.28) for major adverse cardiovascular events, 0.96 (95% CI: 0.69-1.35) for cardiovascular mortality and 1.15 (95% CI: 0.81-1.64) for myocardial infarction. The increased risk of all-cause mortality was also observed in former smokers compared with those who had never smoked (RR: 1.19; 95% CI: 1.03-1.38). Furthermore, the negative effects of cigarette smoking on all-cause mortality were also observed in most subgroups. Cigarette smoking has been shown to increase the likelihood of all-cause mortality in patients after coronary revascularization with PCI or CABG. Smoking cessation is essential for PCI or CABG patients to manage their coronary artery disease.

The impact of cigarette smoking in predicting stroke using CHADS2 and CHA2DS2-VASc schemas

Objective

To determine the impact of smoking status in the prediction of stroke using CHADS₂ and CHA₂DS₂-VASc schemes.

Methods

Five hundred twenty-eight consecutive patients with arrhythmic symptoms and without any documented arrhythmia from Queen Mary Hospital, Hong Kong, were followed up to determine the incidence of ischemic stroke, new-onset atrial fibrillation (AF), or all-cause mortality. Smoking status was classified into nonsmokers and smokers. The pairwise comparisons of C-statistics for outcomes were performed.

Results

During a median follow-up period of 6.2 years, 65 (12.3%) individuals developed ischemic stroke. Smokers experienced higher annual incidence of stroke, a new-onset AF, and all-cause death compare to nonsmokers, with corresponding hazard ratio (HR) of stroke, AF, and all-cause death being 2.51 (95% confidence intervals, CI 1.36als, CIse death bein 1.15a3.24), and 1.95 (95% CI 1.161.95 (95% CIath being 2.51 (95% confidence corr₂ and CHA₂DS₂-VASc for stroke were 0.60 (95% CI 0.51 for stp = 0.09) and 0.59 (95% CI 0.50 (95%, p = 0.15) respectively, whereas the C-statistics of CHADS₂ and CHA₂DS₂-VASc were 0.66 (95% CI 0.61 were 0p = 0.005), 0.75 (95% CI 0.7 CI 0.7p < 0.0001), respectively among nonsmokers. After incorporating smoking, both the CHADS₂-smoking and CHA₂DS₂-VASc-smoking achieved better C-statistics for new-onset ischemic stroke prediction superior to baseline score systems in male groups.

Conclusion

Cigarette smoking status has impact on stroke stratification using CHADS₂ and CHA₂DS₂-VASc scheme. The discrimination of the CHADS₂ and CHA₂DS₂-VASc scheme for stroke can be significantly improved if smoking status is additionally considered.

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.

Impact of current smoking on 2-year clinical outcomes between durable-polymer-coated stents and biodegradable-polymer-coated stents in acute myocardial infarction after successful percutaneous coronary intervention: Data from the KAMIR

Objective

Data concerning the effect of current smoking on solely new-generation drug-eluting stents (DES) are limited. We investigated the impact of current smoking on 2-year clinical outcomes between durable-polymer (DP)-coated DES (zotarolimus-eluting [ZES] and everolimus eluting [EES]) and biodegradable-polymer (BP)-coated biolimus-eluting stent (BES) in acute myocardial infarction (AMI) patients after successful percutaneous coronary intervention (PCI).

Methods

Finally, a total of 8357 AMI patients with current smoking underwent successful PCI with new-generation DES (ZES, EES, and BES) were enrolled and divided into three groups as ZES (n = 3199), EES (n = 3987), and BES group (n = 1171). The primary endpoint was the occurrence of major adverse cardiac events (MACE) defined as all-cause death (cardiac death [CD] or non-cardiac death), recurrent AMI (re-MI), any revascularization (target lesion revascularization [TLR], target vessel revascularization [TVR], and non-TVR). The secondary endpoint was the incidence of definite or probable stent thrombosis (ST).

Results

The 2-year adjusted hazard ratio (HR) of MACE for ZES vs. EES (1.055; 95% confidence interval [CI], 0.843–1.321; p = 0.638), ZES vs. BES (HR, 0.885; 95% CI, 0.626–1.251; p = 0.488), EES vs. BES (HR, 0.889; 95% CI, 0.633–1.250; p = 0.499), and ZES/EES vs. BES (HR, 0.891; 95% CI, 0.648–1.126; p = 0.480) were similar. The occurrence of ST after adjustment were also comparable. In addition, the 2-year adjusted HR for all-cause death, CD, re-MI, TLR, TVR, and non-TVR were not different.

Conclusions

In this study, DP-DES and BP-DES showed comparable safety and efficacy during 2-year follow-up periods. Therefore, DP-DES or BP-DES are equally acceptable in AMI patients with current smoking undergoing PCI.

Meta-Analysis Comparing Outcomes of Smokers Versus Nonsmokers With Acute Coronary Syndrome Underwent Percutaneous Coronary Intervention

Several studies have found improved mortality in smokers after acute coronary syndrome (ACS) especially in the thrombolytic era. We aimed to assess the association of smoking status with mortality and cardiovascular outcomes in patients with ACS treated with percutaneous coronary intervention (PCI). We searched PubMed, EMBASE, CINAHL, and Cochrane CENTRAL for randomized controlled trials since inception through February 15, 2018 and used random effects model for analysis. The outcomes analyzed were all-cause mortality, major adverse cardiac events (MACE), myocardial infarction, and target vessel revascularization at 1 month and 1 year. We included 17 randomized and nonrandomized studies with a total of 55,491 patients with 21,989 smokers' and 33,502 nonsmokers. In ACS patients treated with PCI, smokers were found to have lower mortality than nonsmokers at 30-day ([2.3% vs 3.3%; Odds ratio; 0.54; 95% confidence interval: 0.39 to 0.76; p <0.001, I² = 74%] and 1-year [2.3% vs 3.6%; Odds ratio 0.54 (0.3 to 0.7); p <0.001, I² = 77%]. Meta-regression showed lower mortality in smokers was associated with younger age, man gender, and lower prevalence of diabetes mellitus. No significant differences were observed in myocardial infarction, MACE, and target-vessel revascularization between smokers and nonsmokers. In conclusion, smoking is associated with lower mortality but not MACE in ACS patients treated with PCI at 1-month and 1-year. This association with mortality was strongly associated with younger age, man gender, prevalence of diabetes mellitus, and extent of coronary artery disease.

Clopidogrel Pharmacokinetics in Malaysian Population Groups: The Impact of Inter-Ethnic Variability

Malaysia is a multi-ethnic society whereby the impact of pharmacogenetic differences between ethnic groups may contribute significantly to variability in clinical therapy. One of the leading causes of mortality in Malaysia is cardiovascular disease (CVD), which accounts for up to 26% of all hospital deaths annually. Clopidogrel is used as an adjunct treatment in the secondary prevention of cardiovascular events. CYP2C19 plays an integral part in the metabolism of clopidogrel to the active metabolite clopi-H4. However, CYP2C19 genetic polymorphism, prominent in Malaysians, could influence target clopi-H4 plasma concentrations for clinical efficacy. This study addresses how inter-ethnicity variability within the Malaysian population impacts the attainment of clopi-H4 target plasma concentration under different CYP2C19 polymorphisms through pharmacokinetic (PK) modelling. We illustrated a statistically significant difference (P < 0.001) in the clopi-H4 C_max between the extensive metabolisers (EM) and poor metabolisers (PM) phenotypes with either Malay or Malaysian Chinese population groups. Furthermore, the number of PM individuals with peak clopi-H4 concentrations below the minimum therapeutic level was partially recovered using a high-dose strategy (600 mg loading dose followed by a 150 mg maintenance dose), which resulted in an approximate 50% increase in subjects attaining the minimum clopi-H4 plasma concentration for a therapeutic effect.