Risk Factors for Bleeding and Clinical Ineffectiveness Associated With Clopidogrel Therapy: A Comprehensive Meta-Analysis

Quality of care for secondary cardiovascular disease prevention in 2009-2017: population-wide cohort study of antiplatelet therapy use in Scotland

BACKGROUND

Antiplatelet therapy (APT) can substantially reduce the risk of further vascular events in individuals with established atherosclerotic cardiovascular disease (ASCVD). However, knowledge regarding the extent and determinants of APT use is limited.

OBJECTIVES

Estimate the extent and identify patient groups at risk of suboptimal APT use at different stages of the treatment pathway.

METHODS

Retrospective cohort study using linked NHS Scotland administrative data of all adults hospitalised for an acute ASCVD event (n=150 728) from 2009 to 2017. Proportions of patients initiating, adhering to, discontinuing and re-initiating APT were calculated overall and separately for myocardial infarction (MI), ischaemic stroke and peripheral arterial disease (PAD). Multivariable logistic regression and Cox proportional hazards models were used to assess the contribution of patient characteristics in initiating and discontinuing APT.

RESULTS

Of patients hospitalised with ASCVD, 84% initiated APT: 94% following an MI, 83% following an ischaemic stroke and 68% following a PAD event. Characteristics associated with lower odds of initiation included female sex (22% less likely than men), age below 50 years or above 70 years (aged <50 years 26% less likely, and aged 70-79, 80-89 and ≥90 years 21%, 39% and 51% less likely, respectively, than those aged 60-69 years) and history of mental health-related hospitalisation (45% less likely). Of all APT-treated individuals, 22% discontinued treatment. Characteristics associated with discontinuation were similar to those related to non-initiation.

CONCLUSIONS

APT use remains suboptimal for the secondary prevention of ASCVD, particularly among women and older patients, and following ischaemic stroke and PAD hospitalisations.

Cryo-EM structures of the human P2X1 receptor reveal subtype-specific architecture and antagonism by supramolecular ligand-binding

P2X receptors are a family of seven trimeric non-selective cation channels that are activated by extracellular ATP to play roles in the cardiovascular, neuronal, and immune systems. Although it is known that the P2X1 receptor subtype has increased sensitivity to ATP and fast desensitization kinetics, an underlying molecular explanation for these subtype-selective features is lacking. Here we report high-resolution cryo-EM structures of the human P2X1 receptor in the apo closed, ATP-bound desensitized, and the high-affinity antagonist NF449-bound inhibited states. The apo closed and ATP-bound desensitized state structures of human P2X1 define subtype-specific properties such as distinct pore architecture and ATP-interacting residues. The NF449-bound inhibited state structure of human P2X1 reveals that NF449 has a unique dual-ligand supramolecular binding mode at the interface of neighboring protomers, inhibiting channel activation by overlapping with the canonical P2X receptor ATP-binding site. Altogether, these data define the molecular pharmacology of the human P2X1 receptor laying the foundation for structure-based drug design.

Hemorrhagic Bartholin's cyst in a woman using anti-platelet medication: A case report and review of the literature

BACKGROUND

We report the case of a postmenopausal female with a hemorrhagic Bartholin's cyst who has been using an antiplatelet medication.

CASE SUMMARY

A postmenopausal woman, 84 years of age, had a medical history of hypertension, diabetes mellitus, coronary artery disease (three-vessel disease), chronic kidney disease (stage 3), and dementia. The patient has been taking clopidogrel, an antiplatelet medication, for several years. She presented at our outpatient clinic complaining of painful swelling over her left vulva for several days. A Bartholin's cyst over the left vulva was suspected, and the patient underwent marsupialization under local anesthesia, which was well-tolerated. During the incision procedure, bright-red blood with some blood clots was discharged, and a hemorrhagic Bartholin's cyst was observed. There was no recurrence of the hemorrhagic Bartholin's cyst during the 6-mo subsequent follow-up period.

CONCLUSION

Hemorrhagic Bartholin's cysts rarely occur. We report the case of a postmenopausal female with a hemorrhagic Bartholin's cyst who had been on antiplatelets and was successfully treated with marsupialization. No recurrence was noted during the 6-mo follow-up period. Older females taking antiplatelets should be cautious of bleeding when presenting with a Bartholin's cyst.

Clinical non-effectiveness of clopidogrel use for peripheral artery disease in patients with CYP2C19 polymorphisms: a systematic review

PURPOSE

To conduct a systematic review to identify studies that assessed the association between CYP2C19 polymorphisms and clinical outcomes in peripheral artery disease (PAD) patients who took clopidogrel.

METHODS

We systematically searched Ovid EMBASE, PubMed, and Web of Science from November 1997 (inception) to September 2020. We included observational studies evaluating how CYP2C19 polymorphism is associated with clopidogrel's effectiveness and safety among patients with PAD. We extracted relevant information details from eligible studies (e.g., study type, patient population, study outcomes). We used the Risk of Bias in Non-randomized Studies-of Interventions (ROBINS-I) Tool to assess the risk of bias for included observational studies.

RESULTS

The outcomes of interest were the effectiveness and safety of clopidogrel. The effectiveness outcomes included clinical ineffectiveness (e.g., restenosis). The safety outcomes included bleeding and death related to the use of clopidogrel. We identified four observational studies with a sample size ranging from 50 to 278. Outcomes and comparison groups of the studies varied. Three studies (75%) had an overall low risk of bias. All included studies demonstrated that carrying CYP2C19 loss of function (LOF) alleles was significantly associated with reduced clinical effectiveness and safety of clopidogrel.

CONCLUSIONS

Our systematic review showed an association between CYP2C19 LOF alleles and reduced functions of clopidogrel. The use of CYP2C19 testing in PAD patients prescribed clopidogrel may help improve the clinical outcomes. However, based on the limited evidence, there is a need for randomized clinical trials in PAD patients to test both the effectiveness and safety outcomes of clopidogrel.

Piriformis syndrome as a result of intramuscular haematoma mimicking cauda equina effectively treated with piriformis tendon release

We present a case of piriformis syndrome in a woman in her 30's following low energy trauma, presenting with unilateral lower limb weakness, altered sensation and urinary retention. CT imaging revealed a bulky piriformis muscle which was further clarified on MRI as an intramuscular haematoma within the left piriformis causing compression of the left lumbosacral plexus. Haematoma formation was exacerbated due to use of an antiplatelet medication the patient was taking for Moyamoya disease, which carries an increased risk of cerebrovascular accident. Surgical exploration of the piriformis and sciatic nerve was undertaken and confirmed a haematoma within the piriformis. A full release of the piriformis tendon was undertaken, and the sciatic nerve was inspected, no further abnormality was found. After review in clinic post-discharge, the patient reported normal sensation and normal muscle power in her feet.