Association of Oral Anticoagulation With Stroke in Atrial Fibrillation or Heart Failure: A Comparative Meta-Analysis

Background and Purpose

Atrial fibrillation and heart failure with reduced ejection fraction (HFrEF) are common sources of cardioembolism. While oral anticoagulation is strongly recommended for atrial fibrillation, there are marked variations in guideline recommendations for HFrEF due to uncertainty about net clinical benefit. This systematic review and meta-analysis evaluates the comparative association of oral anticoagulation with stroke and other cardiovascular risk in populations with atrial fibrillation or HFrEF in sinus rhythm and identify factors mediating different estimates of net clinical benefit.

Methods

PubMed and Embase were searched from database inception to November 20, 2019 for randomized clinical trials comparing oral anticoagulation to control. A random-effects meta-analysis was used to estimate a pooled treatment-effect overall and within atrial fibrillation and HFrEF trials. Differences in treatment effect were assessed by estimating I2 among all trials and testing the between-trial-population P-interaction. The primary outcome measure was all stroke. Secondary outcome measures were ischemic stroke, hemorrhagic stroke, mortality, myocardial infarction, and major hemorrhage.

Results

Twenty-one trials were eligible for inclusion, 15 (n=19 332) in atrial fibrillation (mean follow-up: 23.1 months), and 6 (n=9866) in HFrEF (mean follow-up: 23.9 months). There were differences in primary outcomes between trial populations, with all-cause mortality included for 95.2% of HFrEF trial population versus 0.38% for atrial fibrillation. Mortality was higher in controls groups of HFrEF populations (19.0% versus 9.6%) but rates of stroke lower (3.1% versus 7.0%) compared with atrial fibrillation. The association of oral anticoagulation with all stroke was consistent for atrial fibrillation (odds ratio, 0.51 [95% CI, 0.42–0.63]) and HFrEF (odds ratio, 0.61 [95% CI, 0.47–0.79]; I2=12.4%; P interaction=0.31). There were no statistically significant differences in the association of oral anticoagulation with cardiovascular events, mortality or bleeding between populations.

Conclusions

The relative association of oral anticoagulation with stroke risk, and other cardiovascular outcomes, is similar for patients with atrial fibrillation and HFrEF. Differences in the primary outcomes employed by trials in HFrEF, compared with atrial fibrillation, may have contributed to differing conclusions of the relative efficacy of oral anticoagulation.

Combined influence of ABCB1 genetic polymorphism and DNA methylation on aspirin resistance in Chinese ischemic stroke patients

Genetic variants of ABCB1 may affect intestinal absorption of aspirin (ASA). However, it is unclear whether ABCB1 polymorphisms and DNA methylation are associated with ASA efficacy for ischemic stroke. Our aims is to investigate the association between ABCB1 polymorphisms and methylation status on the antiplatelet effects of ASA in Chinese Han ischemic stroke patients. This is a prospective cohort analysis of eligible stroke patients who received ASA. Patients were divided into two groups according to the thrombelastogram and platelet aggregation test: aspirin resistance (AR) and aspirin-sensitive (AS) groups. The ABCB1 genetic polymorphism and the methylation status of promoter regions were analyzed using PCR-RFLP and the combined bisulfite restriction analysis (COBRA). The number of genotype CC + TT of C3435T in the AR group was greater than that of the AS group (p = 0.007). The DNA methylation levels of ABCB1 promoter in the AS group was higher than that of the AR group (p < 0.001), and the promoter methylation levels showed significant different among the CC, CT, and TT genotypes of C3435T individuals (p = 0.006), while there was no obvious difference between different genotypes of C1236T and G2677T/A polymorphisms (p > 0.05). We also found that the methylation status of the ABCB1 promoter correlated positively with arachidonic acid inhibition (AA%) (R = 0.781, p < 0.001).The ABCB1 polymorphism and methylation status was associated with the reduced efficacy of ASA treatment in ischemic stroke. Genetic polymorphism and DNA methylation of ABCB1 should be concerned when prescribing ASA.

Platelet function in stroke/transient ischemic attack patients treated with tocotrienol

The purpose of this study was to characterize the effects of tocotrienol form of vitamin E (TCT) on platelet function in patients with stroke or transient ischemic attack (TIA). A double blind, randomized, single center phase II clinical trial was conducted comparing placebo (PBO) and 400 and 800 mg TCT daily for a year in 150 patients with a sentinel ischemic stroke or TIA event in the prior 6 months. Platelet function was measured at baseline and then, at 3 month intervals for a year, using light transmission aggregometry. The incidence of aspirin resistance in aspirin-treated patients or platelet inhibition in patients on clopidogrel alone was compared between the three treatment groups. Results showed that in patients taking aspirin and clopidogrel, the incidence of aspirin resistance was significantly decreased from 40% in PBO-treated patients to 9% in the 400 mg TCT group and 25% in the TCT 800 mg group (P = .03). In conclusion, patients on aspirin and clopidogrel had a higher incidence of aspirin resistance than all patients treated with aspirin alone and TCT decreased the frequency of aspirin resistance in this group.

Intragastric acidity and omeprazole exposure during dosing with either PA32540 (enteric-coated aspirin 325 mg + immediate-release omeprazole 40 mg) or enteric-coated aspirin 325 mg + enteric-coated omeprazole 40 mg - a randomised, phase 1, crossover study

BACKGROUND

Aspirin therapy is associated with adverse upper gastrointestinal effects. PA32540 is a coordinated-delivery tablet containing enteric-coated aspirin (EC-ASA) 325 mg and immediate-release (IR) omeprazole 40 mg. Immediate-release omeprazole (located in outer layer of tablet) is available for instantaneous dissolution rapidly after ingestion, while dissolution of the EC-ASA core is delayed until pH >5.5.

AIM

To compare the pharmacodynamic and pharmacokinetic effects of PA32540 (EC-ASA 325 mg + IR-omeprazole 40 mg) vs. enteric-coated (EC)-omeprazole 40 mg.

METHODS

This single-centre, open-label, randomised, two-way crossover study in healthy volunteers compared 7 days of once-daily dosing with PA32540 with 7 days of once-daily EC-ASA 325 mg + EC-omeprazole 40 mg dosed concomitantly. The primary endpoint was per cent time intragastric pH >4 over 24 h on Day 7. A key secondary endpoint was determination of the pharmacokinetics of omeprazole and salicylic acid.

RESULTS

Twenty-six subjects (mean age 29 years) were enrolled into the study. On Day 7, mean per cent time intragastric pH >4 was 50.6% for PA32540 and 57.6% for EC-omeprazole 40 mg (P = 0.004) and geometric least squares mean AUC0-24 for omeprazole was 1446 h*ng/mL for PA32540 and 2558 h*ng/mL for EC-omeprazole 40 mg. Day 7 median Tmax of omeprazole was 0.5 h for PA32540 and 1.25 h for EC-omeprazole 40 mg.

CONCLUSION

Total exposure to omeprazole from PA32540 was 57% of that from EC-omeprazole for the same dose amount (40 mg), while absolute difference in 24-h acid control was 7%. Omeprazole exposure and pH control with PA32540 appear similar to EC-omeprazole 20 mg.