Gut microbiota-derived metabolite trimethylamine-N-oxide (TMAO) is emerging as a new potentially important cause of increased cardiovascular risk. The purpose of this meta-analysis was to systematically estimate and quantify the association between TMAO plasma levels, mortality, and major adverse cardio and cerebrovascular events (MACCE). MEDLINE, ISI Web of Science, and SCOPUS databases were searched for ad hoc studies published up to April 2017. Associations between TMAO plasma levels, all-cause mortality (primary outcome) and MACCE (secondary outcome) were systematically addressed. A total of 17 clinical studies were included in the analytic synthesis, enrolling 26 167 subjects. The mean follow-up in our study population was 4.3 ± 1.5 years. High TMAO plasma levels were associated with increased incidence of all-cause mortality [14 studies for 16 cohorts enrolling 15 662 subjects, hazard ratio (HR): 1.91; 95% confidence interval (CI): 1.40–2.61, P < 0.0001, I² = 94%] and MACCE (5 studies for 6 cohorts enrolling 13 944 subjects, HR: 1.67, 95% CI: 1.33–2.11, P < 0.00001, I² = 46%,). Dose-response meta-analysis revealed that the relative risk (RR) for all-cause mortality increased by 7.6% per each 10 μmol/L increment of TMAO [summary RR: 1.07, 95% CI (1.04–1.11), P < 0.0001; based on seven studies]. Association of TMAO and mortality persisted in all examined subgroups and across all subject populations. This is the first systematic review and meta-analysis demonstrating the positive dose-dependent association between TMAO plasma levels and increased cardiovascular risk and mortality.

Aims: To investigate the safety and efficacy of double vs. triple antithrombotic therapy (DAT vs. TAT) in patients with atrial fibrillation (AF) and acute coronary syndrome or who underwent percutaneous coronary intervention (PCI). Methods and results: A systematic review and meta-analysis was performed using PubMed to search for non-vitamin K antagonist oral anticoagulant (NOAC)-based randomized clinical trials comparing DAT vs. TAT in AF patients undergoing PCI. Four trials encompassing 10 234 patients (DAT = 5496 vs. TAT = 4738) were included. The primary safety endpoint (ISTH major or clinically relevant non-major bleeding) was significantly lower with DAT compared with TAT [risk ratio (RR) 0.66, 95% confidence interval (CI) 0.56–0.78; P < 0.0001; I 2 = 69%], which was consistent across all available bleeding definitions. This benefit was counterbalanced by a significant increase of stent thrombosis (RR 1.59, 95% CI 1.01–2.50; P = 0.04; I 2 = 0%) and a trend towards higher risk of myocardial infarction with DAT. There were no significant differences in all-cause and cardiovascular death, stroke and major adverse cardiovascular events. The comparison of NOAC-based DAT vs. vitamin K antagonist (VKA)-TAT yielded consistent results and a significant reduction of intracranial haemorrhage (RR 0.33, 95% CI 0.17–0.65; P = 0.001; I 2 = 0%). Conclusion: Double antithrombotic therapy, particularly if consisting of a NOAC instead of VKA and a P2Y12 inhibitor, is associated with a reduction of bleeding, including major and intracranial haemorrhages. This benefit is however counterbalanced by a higher risk of cardiac—mainly stent-related—but not cerebrovascular ischaemic occurrences.

Aims: After percutaneous coronary intervention (PCI) with second-generation drug-eluting stent (DES), whether short dual antiplatelet therapy (DAPT) followed by single antiplatelet therapy (SAPT) with a P2Y12 receptor inhibitor confers benefits compared with prolonged DAPT is unclear. Methods and results: Multiple electronic databases, including PubMed, Scopus, Web of Sciences, Ovid, and ScienceDirect, were searched to identify randomized clinical trials comparing ≤3 months of DAPT followed by P2Y12 inhibitor SAPT vs. 12 months of DAPT after PCI with second-generation DES implantation. The primary and co-primary outcomes of interest were major bleeding and stent thrombosis 1 year after randomization. Summary hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated by fixed-effect and random-effects models. Multiple sensitivity analyses including random-effects models 95% CI adjustment were applied. A sensitivity analysis comparing trials using P2Y12 inhibitor SAPT with those using aspirin SAPT was performed. A total of five randomized clinical trials (32 145 patients) were available. Major bleeding was significantly lower in the patients assigned to short DAPT followed by P2Y12 inhibitor SAPT compared with those assigned to 12-month DAPT (random-effects model: HR 0.63, 95% 0.45–0.86). No significant differences between groups were observed in terms of stent thrombosis (random-effects model: HR 1.19, 95% CI 0.86–1.65) and the secondary endpoints of all-cause death (random-effects model: HR 0.85, 95% CI 0.70–1.03), myocardial infarction (random-effects model: HR 1.05, 95% CI 0.89–1.23), and stroke (random-effects model: HR 1.08, 95% CI 0.68–1.74). Sensitivity analyses showed overall consistent results. By comparing trials testing ≤3 months of DAPT followed by P2Y12 inhibitor SAPT vs. 12 months of DAPT with trials testing ≤3 months of DAPT followed by aspirin SAPT vs. 12-month of DAPT, there was no treatment-by-subgroup interaction for each endpoint. By combining all these trials, regardless of the type of SAPT, short DAPT was associated with lower major bleeding (random-effects model: HR 0.63, 95% CI 0.48–0.83) and no differences in stent thrombosis, all-cause death, myocardial infarction, and stroke were observed between regimens. Conclusion: After second-generation DES implantation, 1–3 months of DAPT followed by P2Y12 inhibitor SAPT is associated with lower major bleeding and similar stent thrombosis, all-cause death, myocardial infarction, and stroke compared with prolonged DAPT. Whether P2Y12 inhibitor SAPT is preferable to aspirin SAPT needs further investigation.