Downstream cangrelor versus upstream ticagrelor in patients with ST-segment elevation myocardial infarction: A propensity score-matched analysis.

BACKGROUND: Pretreatment with a P2Y12 inhibitor may be considered in patients with ST-segment elevation myocardial infarction (STEMI) referred to percutaneous coronary intervention (PCI). Intravenous cangrelor is an alternative in this setting, where oral absorption can be hindered. The aim of this study was to compare cangrelor administered after coronary angiography (i.e., "downstream") and ticagrelor pretreatment (i.e., "upstream"). METHODS: STEMI patients undergoing PCI from October 2019 to June 2023 were included. The primary outcome was the composite of in-hospital major adverse cardiovascular events (MACE). Secondary outcomes included individual components of the primary outcome and in-hospital major bleeding. Univariable and multivariable regression analyses were performed in unmatched and propensity-matched cohorts. RESULTS: Of 6086 patients enrolled in the prospective CAST registry, 761 were included: 383 (50.3 %) received downstream cangrelor and 378 (49.7 %) upstream ticagrelor. In the matched population, no between-group differences were observed in MACE (odds ratio [OR] 1.30; 95 % confidence interval [CI] 0.79-2.17; P 0.308), all-cause death (OR 1.91; 95 % CI 0.87-4.54; P 0.124), myocardial infarction (OR 2.64; 95 % CI 0.76-12.14; P 0.154), stent thrombosis (OR 0.38; 95 % CI 0.06-1.80; P 0.255), unplanned repeat revascularization (OR 1.22; 95 % CI 0.32-4.98; P 0.766) and major bleeding (OR 0.98; 95 % CI 0.50-1.93; P 0.955). Cardiogenic shock and bailout administration of glycoprotein IIb/IIIa inhibitors were independent predictors of MACE, while radial access showed an inverse association with the primary outc. CONCLUSIONS: In P2Y12-naïve STEMI patients undergoing primary PCI, no significant differences were noted in the risk of in-hospital ischemic and bleeding events between downstream cangrelor and upstream ticagrelor.

Antithrombotic Therapy in Patients with Chronic Coronary Syndromes.

The antithrombotic management of chronic coronary syndrome (CCS) involves a 6-month course of dual antiplatelet therapy (DAPT), followed by chronic aspirin therapy. In patients with a baseline indication for anticoagulation, a variable duration of triple antithrombotic therapy is administered, followed by dual antithrombotic therapy until the sixth month post-percutaneous coronary intervention (PCI), and ultimately a transition to chronic anticoagulation. However, advancements in stent technology reducing the risk of stent thrombosis and a growing focus on the impact of bleeding on prognosis have prompted the development of new therapeutic strategies. These strategies aim to enhance protection against ischemic events in the initial stages after PCI while mitigating the risk of bleeding in the long term. This article delineates the therapeutic strategies outlined in European and American guidelines for CCS management, with special attention to investigational strategies.

Assessment of Noninferiority Margins in Cardiovascular Medicine Trials.

Background: Noninferiority trials are increasingly common in cardiovascular medicine, but their reporting and interpretation are challenging, particularly when an absolute risk difference is used as noninferiority margin. Objectives: This study aimed to investigate the effect of using absolute rather than relative noninferiority margins in cardiovascular trials. Methods: We reviewed noninferiority trials presented at major cardiovascular conferences from 2015 to 2022 and published within the same period. Based on the actual versus anticipated event rates in the control group, we recalculated the absolute noninferiority margin and re-assessed the trial results. The primary outcome of interest was the proportion of trials with a different interpretation after recalculation. Additionally, we analyzed the conclusion statements of these trials to determine if cautionary notes for the interpretation of study results were included. Results: We analyzed a total of 768 trials, of which 88 had a noninferiority design and 66 used an absolute noninferiority margin. Of 48 comparisons from 45 trials qualifying for the analysis, 11 (22.9%) had divergent results after recalculation of the absolute noninferiority margin based on the observed rather than anticipated event rate. Ten trials originally claiming noninferiority, did not meet it after the margin recalculation. All of them did not include statements suggesting cautionary interpretation of the study results in the conclusion section. Compared with the other trials, these displayed a larger median difference between anticipated and recalculated noninferiority margins (44.7% [IQR: 38.6%-56.7%] vs 15.3% [IQR: -1.5% to 28.9%]; P < 0.001). Conclusions: Recalculating noninferiority margins based on actual event rates, rather than anticipated ones, led to different outcomes in approximately 1 out of 4 cardiovascular trials, with most divergent trials lacking cautionary interpretation. These findings emphasize the importance of using or supplementing the relative noninferiority margin, particularly in studies with significant deviations between observed and expected event rates. This underscores the critical need for enhanced methodological and reporting standards in noninferiority trials, especially those employing absolute margins.

Characteristics and Impact of Randomized Trials on Drugs or Devices in Cardiovascular Medicine.

INTRODUCTION: Clinical trials, essential for medical advancement, vary significantly in methodology and regulatory pathways depending on the type of therapeutic intervention (i.e., drugs or devices). This study aimed to determine whether the drug or device intervention types influence the impact of randomized trials in cardiovascular medicine. METHODS: We analyzed late-breaking randomized controlled trials presented at major cardiology conferences from 2015 to 2021. The primary endpoint was the total number of citations obtained. Secondary endpoints included the number of citations at 1 and 2 years, number of total and 1-year mentions, and several metrics of study conduct and publication. Statistical analysis included tests for comparisons of continuous or categorical variables, based on their distribution, as appropriate. To adjust the results for potential confounders, univariable and multivariable regression models were utilized. Additionally, sensitivity analyses were conducted to explore both the effect of neutral or positive study outcomes on the comparative impact of drug versus device trials and the impact of the coronavirus disease 2019 (COVID-19) pandemic on the primary endpoint. RESULTS: Of 382 eligible randomized trials, 227 (59.4%) were trials of drugs and 155 (40.6%) were trials of devices. Drug trials had a higher median number of total citations compared to device studies (93 [interquartile range {IQR} 48-137] vs. 82 [IQR 39-192]; p = 0.025). This difference was consistent at 1 and 2 years and was also observed in the number of total mentions and mentions at 1 year. All the metrics of study conduct and publication were similar, except for drug studies being more often stopped prematurely (8.8 vs. 1.9%; p = 0.006). After adjusting for multiple potential confounders, the difference in citations and mentions was no longer statistically significant. However, drug trials remained more likely to be stopped prematurely (adjusted odds ratio = 1.15; 95% confidence interval 1.03-1.28; p = 0.009). Positive study outcomes significantly influenced the number of citations and the likelihood of a trial being stopped prematurely. CONCLUSIONS: Drug trials are often stopped early and receive more citations and mentions than device trials. However, these differences are mainly due to factors other than the treatment itself. Studies published simultaneously tend to get more attention, and drug trials with positive results are cited more often than those with neutral results.

P2Y12 Inhibitor Monotherapy After Short DAPT in Acute Coronary Syndrome: A Systematic Review and Meta-analysis.

BACKGROUND: P2Y12 inhibitor monotherapy after a short course of dual antiplatelet therapy (DAPT) may balance ischemic and bleeding risks in patients with acute coronary syndrome (ACS). However, it remains uncertain how different P2Y12 inhibitors used as monotherapy affect outcomes. METHODS: Randomized controlled trials comparing P2Y12 inhibitor monotherapy after a short course of DAPT (≤3 months) versus 12-month DAPT in ACS were included. The primary endpoint was major adverse cardiovascular events (MACE). All analyses included an interaction term for the P2Y12 inhibitor used as monotherapy. Trial sequential analysis were run to explore whether the effect estimate of each outcomes may be affected by further studies. RESULTS: Seven trials encompassing 27,284 ACS patients were included. Compared with 12-month DAPT, P2Y12 inhibitor monotherapy after a short course of DAPT was associated with no difference in MACE (OR 0.92, 95% CI 0.76-1.12) and a significant reduction in net adverse clinical events (NACE) (OR 0.75; 95% CI 0.60-0.94), any bleeding (OR 0.54, 95% CI 0.43-0.66) and major bleeding (OR 0.47, 95% CI 0.37-0.60). Significant interactions for subgroup difference between ticagrelor and clopidogrel monotherapy were found for MACE (pint=0.016), all-cause death (pint=0.042), NACE (pint=0.018), and myocardial infarction (pint=0.028). Trial sequential analysis showed conclusive evidence of improved NACE with ticagrelor, but not with clopidogrel monotherapy, compared with standard DAPT. CONCLUSIONS: In patients with ACS, P2Y12 inhibitor monotherapy after short DAPT halves bleeding without increasing ischemic events compared with standard DAPT. Ticagrelor, but not clopidogrel monotherapy, reduced MACE, NACE and mortality compared with standard DAPT, supporting its use after aspirin discontinuation. Protocol registration: This study is registered in PROSPERO (CRD42023494797).

Gender equality in medical research: A cardiology-informed examination.

Despite a perceived increase in attention to gender differences in medicine, a comprehensive assessment of gender equality research, particularly in cardiology, remains underexplored. This observational retrospective study, focusing on documents related to "Gender Equality" according to the Sustainable Development Goals, reveals cardiology as a significant area for gender equality research, albeit with a decline in publications post-2018. The analysis highlighted a concentrated effort in the United States and a considerable impact gap between gender-focused and general cardiology research. The global academic community must intensify research into gender disparities, which is essential for achieving professional gender equality and addressing the burden of cardiovascular diseases.

Percutaneous interventions for pulmonary embolism.

Pulmonary embolism (PE) ranks as a leading cause of in-hospital mortality and the third most common cause of cardiovascular death. The spectrum of PE manifestations varies widely, making it difficult to determine the best treatment approach for specific patients. Conventional treatment options include anticoagulation, thrombolysis, or surgery, but emerging percutaneous interventional procedures are being investigated for their potential benefits in heterogeneous PE populations. These novel interventional techniques encompass catheter-directed thrombolysis, mechanical thrombectomy, and hybrid approaches combining different mechanisms. Furthermore, inferior vena cava filters are also available as an option for PE prevention. Such interventions may offer faster improvements in right ventricular function, as well as in pulmonary and systemic haemodynamics, in individual patients. Moreover, percutaneous treatment may be a valid alternative to traditional therapies in high bleeding risk patients and could potentially reduce the burden of mortality related to major bleeds, such as that of haemorrhagic strokes. Nevertheless, the safety and efficacy of these techniques compared to conservative therapies have not been conclusively established. This review offers a comprehensive evaluation of the current evidence for percutaneous interventions in PE and provides guidance for selecting appropriate patients and treatments. It serves as a valuable resource for future researchers and clinicians seeking to advance this field. Additionally, we explore future perspectives, proposing "percutaneous primary pulmonary intervention" as a potential paradigm shift in the field.

Coronary Angiography, Intravascular Ultrasound, and Optical Coherence Tomography for Guiding of Percutaneous Coronary Intervention: A Systematic Review and Network Meta-Analysis.

BACKGROUND: Results from multiple randomized clinical trials comparing outcomes after intravascular ultrasound (IVUS)- and optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) with invasive coronary angiography (ICA)-guided PCI as well as a pivotal trial comparing the 2 intravascular imaging (IVI) techniques have provided mixed results. METHODS: Major electronic databases were searched to identify eligible trials evaluating at least 2 PCI guidance strategies among ICA, IVUS, and OCT. The 2 coprimary outcomes were target lesion revascularization and myocardial infarction. The secondary outcomes included ischemia-driven target lesion revascularization, target vessel myocardial infarction, death, cardiac death, target vessel revascularization, stent thrombosis, and major adverse cardiac events. Frequentist random-effects network meta-analyses were conducted. The results were replicated by Bayesian random-effects models. Pairwise meta-analyses of the direct components, multiple sensitivity analyses, and pairwise meta-analyses IVI versus ICA were supplemented. RESULTS: The results from 24 randomized trials (15 489 patients: IVUS versus ICA, 46.4%, 7189 patients; OCT versus ICA, 32.1%, 4976 patients; OCT versus IVUS, 21.4%, 3324 patients) were included in the network meta-analyses. IVUS was associated with reduced target lesion revascularization compared with ICA (odds ratio [OR], 0.69 [95% CI, 0.54-0.87]), whereas no significant differences were observed between OCT and ICA (OR, 0.83 [95% CI, 0.63-1.09]) and OCT and IVUS (OR, 1.21 [95% CI, 0.88-1.66]). Myocardial infarction did not significantly differ between guidance strategies (IVUS versus ICA: OR, 0.91 [95% CI, 0.70-1.19]; OCT versus ICA: OR, 0.87 [95% CI, 0.68-1.11]; OCT versus IVUS: OR, 0.96 [95% CI, 0.69-1.33]). These results were consistent with the secondary outcomes of ischemia-driven target lesion revascularization, target vessel myocardial infarction, and target vessel revascularization, and sensitivity analyses generally did not reveal inconsistency. OCT was associated with a significant reduction of stent thrombosis compared with ICA (OR, 0.49 [95% CI, 0.26-0.92]) but only in the frequentist analysis. Similarly, the results in terms of survival between IVUS or OCT and ICA were uncertain across analyses. A total of 25 randomized trials (17 128 patients) were included in the pairwise meta-analyses IVI versus ICA where IVI guidance was associated with reduced target lesion revascularization, cardiac death, and stent thrombosis. CONCLUSIONS: IVI-guided PCI was associated with a reduction in ischemia-driven target lesion revascularization compared with ICA-guided PCI, with the difference most evident for IVUS. In contrast, no significant differences in myocardial infarction were observed between guidance strategies.

Periprocedural myocardial infarction and injury.

Periprocedural myocardial infarction (PMI) and injury, pertinent to both cardiac and non-cardiac procedures, have gained increasing recognition in clinical practice. Over time, diverse definitions for diagnosing PMI have been developed and validated among patient populations undergoing coronary revascularization. However, this variety in definitions presents considerable challenges in clinical settings and complicates both the design and interpretation of clinical trials. The necessity to accurately diagnose PMI has spurred significant interest in establishing universally accepted and prognostically meaningful thresholds for cardiac biomarkers elevation and supportive ancillary criteria. In fact, elevations in cardiac biomarkers in line with the 4th Universal Definition of Myocardial Infarction, have been extensively confirmed to be associated with increased mortality and cardiovascular events. In the context of non-coronary cardiac procedures, such as Transcatheter Aortic Valve Implantation, there is a growing acknowledgment of both the high incidence rates and the adverse impact of PMI on patient outcomes. Similarly, emerging research underscores the significance of PMI and injury in non-cardiac surgery, highlighting the urgent need for effective prevention and risk management strategies in this domain.

Pharmacological and clinical appraisal of factor XI inhibitor drugs.

The evolution of anticoagulation therapy, from vitamin K antagonists to the advent of direct oral anticoagulants (DOACs) almost two decades ago, marks significant progress. Despite improved safety demonstrated in pivotal trials and post-marketing observations, persistent concerns exist, particularly regarding bleeding risk and the absence of therapeutic indications in specific subgroups or clinical contexts. Factor XI (FXI) has recently emerged as a pivotal contributor to intraluminal thrombus formation and growth, playing a limited role in sealing vessel wall injuries. Inhibiting FXI presents an opportunity to decouple thrombosis from haemostasis, addressing concerns related to bleeding events while safeguarding against thromboembolic events. Notably, FXI inhibition holds promise for patients with end-stage renal disease or cancer, where clear indications for DOACs are currently lacking. Various compounds have undergone design, testing, and progression to phase 2 clinical trials, demonstrating a generally favourable safety and tolerability profile. However, validation through large-scale phase 3 trials with sufficient power to assess both safety and efficacy outcomes is needed. This review comprehensively examines FXI inhibitors, delving into individual classes, exploring their pharmacological properties, evaluating the latest evidence from randomized trials, and offering insights into future perspectives.

Association of trial characteristics with simultaneous publication and its impact on citations and mentions: a cross-sectional study.

INTRODUCTION AND OBJECTIVES: Randomized trials are often presented at medical conferences and published simultaneously or later. Predictors of simultaneous publication and its consequences are undetermined. Our aim was to characterize the practice of simultaneous publication, identify its predictors, and evaluate its impact. METHODS: In this cross-sectional study, we included randomized trials presented at late-breaking science sessions of major cardiovascular conferences from 2015 to 2021. The association of trial characteristics with the timing of publication was analyzed. The impact of simultaneous vs nonsimultaneous publication was investigated on the number of 1-year citations and 1-month mentions, and the total citations and mentions at the longest observation follow-up. RESULTS: Of 478 trials included in the analysis, 48.7% were published simultaneously. Simultaneous publications were more likely to be presented in the main conference room (OR, 6.09; 95%CI, 1.34-36.92; P=.029) and were characterized by a shorter review time (OR, 0.95; 95%CI, 0.91-0.96; P<.001). Simultaneous publications were associated with higher 1-year citations (R2, 43.81; 95%CI, 23.89-63.73; P<.001), 1-month mentions (R2, 132.32; 95%CI, 85.42-179.22; P<.001) and total citations (R2, 222.89; 95%CI, 127.98-317.80; P<.001). CONCLUSIONS: Randomized trials presented in the main conference room and with shorter review time were more likely to be published simultaneously. Simultaneous publications were associated with more citations and mentions than nonsimultaneous publications.

PCSK9 inhibitors: current status and emerging frontiers in lipid control.

INTRODUCTION: Atherosclerotic cardiovascular disease (ASCVD) is a leading cause of global mortality, imposing substantial healthcare economic burdens. Among the modifiable risk factors, hypercholesterolemia, especially elevated low-density lipoprotein cholesterol (LDL-C), plays a pivotal role in ASCVD development. Novel therapies such as PCSK9 (Proprotein Convertase Subtilisin/Kexin type 9) inhibitors are emerging to address this concern. These inhibitors offer the potential to reduce ASCVD risk by directly targeting LDL-C levels. AREAS COVERED: The article reviews the structural and functional aspects of PCSK9, highlighting its role in LDL receptor regulation. The pharmacological strategies for PCSK9 inhibition, including monoclonal antibodies, binding peptides, gene silencing, and active immunization, are explored. Clinical evidence from various trials underscores the safety and efficacy of PCSK9 inhibitors in reducing LDL-C levels and potentially improving cardiovascular outcomes. Despite these promising results, challenges such as cost-effectiveness and long-term safety considerations are addressed. EXPERT OPINION: Among PCSK9 inhibitors, monoclonal antibodies represent a cornerstone. Many trials have showed their efficacy in reducing LDL-C and the risk for major adverse clinical events, revealing long-lasting effects, with special benefits particularly for statin-intolerant and familial hypercholesterolemia patients. However, long-term impacts, high costs, and patient selection necessitate further research.

Evaluating the pharmacokinetic and pharmacodynamic impact of different modes of ticagrelor administration.

INTRODUCTION: Alternative administration modes for oral P2Y12 inhibitors, particularly ticagrelor, have emerged as a potential alternative to overcome the limitations associated with the delayed onset of action of these drugs in patients who are unable to swallow or with impaired absorption. AREAS COVERED: This comprehensive literature review aims to provide an overview of the current state of knowledge on the pharmacokinetics and administration modes of ticagrelor, including factors that may affect its action. It also compares the pharmacokinetics of ticagrelor with that of other drugs with similar uses to provide a comprehensive understanding of the potential advantages and limitations of different modalities of P2Y12 administration. For this purpose, Embase, Medline, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, Google Scholar, and ClinicalTrials.gov were searched from database inception to July 2023. EXPERT OPINION: Among the different alternatives, crushed formulations, especially for ticagrelor, have emerged as the most promising option, showing early and robust platelet inhibition. However, important questions remain unanswered, such as the comparative clinical benefits of crushed ticagrelor versus standard administration, the cost-effectiveness of alternative modes compared to intravenous P2Y12 inhibitors such as cangrelor, and the important limitations associated with the concomitant use of opioids, who have been proven to impair even the action of crushed ticagrelor.

Complete Percutaneous Coronary Revascularization in Acute Coronary Syndromes With Multivessel Coronary Disease: A Systematic Review.

Multivessel disease (MVD) affects approximately 50% of patients with acute coronary syndromes (ACS) and is significantly burdened by poor outcomes and high mortality. It represents a clinical challenge in patient management and decision making and subtends an evolving research area related to the pathophysiology of unstable plaques and local or systemic inflammation. The benefits of complete revascularization are established in hemodynamically stable ACS patients with MVD, and guidelines provide some reference points to inform clinical practice, based on an evidence level that is solid for ST-segment elevation myocardial infarction and less robust for non-ST-segment elevation myocardial infarction and cardiogenic shock. However, several areas of uncertainty remain, such as the optimal timing for complete revascularization or the best guiding strategy for intermediate stenoses. We performed a systematic review of current evidence in the field of percutaneous revascularization in ACS and MVD, also including future perspectives from ongoing trials that will directly compare different timing strategies and investigate the role of invasive and noninvasive guidance techniques. (Complete percutaneous coronary revascularization in patients with acute myocardial infarction and multivessel disease; CRD42022383123).

Antithrombotic Therapy for Primary and Secondary Prevention of Ischemic Stroke: JACC State-of-the-Art Review.

Stroke is a devastating condition with significant morbidity and mortality worldwide. Antithrombotic therapy plays a crucial role in both primary and secondary prevention of stroke events. Single or dual antiplatelet therapy is generally preferred in cases of large-artery atherosclerosis and small-vessel disease, whereas anticoagulation is recommended in conditions of blood stasis or hypercoagulable states that mostly result in red thrombi. However, the benefit of antithrombotic therapies must be weighed against the increased risk of bleeding, which can pose significant challenges in the pharmacological management of this condition. This review provides a comprehensive summary of the currently available evidence on antithrombotic therapy for ischemic stroke and outlines an updated therapeutic algorithm to support physicians in tailoring the strategy to the individual patient and the underlying mechanism of stroke.

Eligibility to Intensified Antithrombotic Regimens for Secondary Prevention in Patients Who Underwent Percutaneous Coronary Intervention.

Single antiplatelet therapy (SAPT) and intensified antithrombotic regimens (prolonged dual antiplatelet therapy [DAPT] or dual pathway inhibition [DPI]) are recommended for secondary prevention in patients who underwent percutaneous coronary intervention (PCI) after initial DAPT. We aimed to characterize eligibility to such strategies and to explore to what extent guidelines are applied in clinical practice. Patients who underwent PCI for acute or chronic coronary syndrome who completed initial DAPT were analyzed from a prospective registry. Patients were categorized into SAPT, prolonged DAPT/DPI, or DPI groups as per guideline indication by using a risk stratification algorithm. Predictors of receiving intensified regimens and the divergency of practice from guidelines were investigated. Between October 2019 and September 2021, a total of 819 patients were included. Based on the guidelines, 83.7% of patients qualified for SAPT, 9.6% for any intensified regimen (i.e., prolonged DAPT or DPI), and 6.7% for DPI only. At multivariable analysis, patients were more likely to receive an intensified regimen if they had diabetes, dyslipidemia, peripheral artery disease, multivessel disease, or previous myocardial infarction. Conversely, they were less likely to receive an intensified regimen if they had atrial fibrillation, chronic kidney disease, or previous stroke. Guidelines were not followed in 18.3% of cases. In particular, only 14.3% of candidates to intensified regimens were treated accordingly. In conclusion, although the majority of patients who underwent PCI after the initial period of DAPT were eligible for SAPT, 1 out of 6 had an indication to intensified regimens. However, such intensified regimens were underused among eligible patients.

Pharmacology and Clinical Development of Factor XI Inhibitors.

Therapeutic anticoagulation is indicated for a variety of circumstances and conditions in several fields of medicine to prevent or treat venous and arterial thromboembolism. According to the different mechanisms of action, the available parenteral and oral anticoagulant drugs share the common principle of hampering or blocking key steps of the coagulation cascade, which unavoidably comes at the price of an increased propensity to bleed. Hemorrhagic complications affect patient prognosis both directly and indirectly (ie, by preventing the adoption of an effective antithrombotic strategy). Inhibition of factor XI (FXI) has emerged as a strategy with the potential to uncouple the pharmacological effect and the adverse events of anticoagulant therapy. This observation is based on the differential contribution of FXI to thrombus amplification, in which it plays a major role, and hemostasis, in which it plays an ancillary role in final clot consolidation. Several agents were developed to inhibit FXI at different stages (ie, suppressing biosynthesis, preventing zymogen activation, or impeding the biological action of the active form), including antisense oligonucleotides, monoclonal antibodies, small synthetic molecules, natural peptides, and aptamers. Phase 2 studies of different classes of FXI inhibitors in orthopedic surgery suggested that dose-dependent reductions in thrombotic complications are not paralleled by dose-dependent increases in bleeding compared with low-molecular-weight heparin. Likewise, the FXI inhibitor asundexian was associated with lower rates of bleeding compared with the activated factor X inhibitor apixaban in patients with atrial fibrillation, although no evidence of a therapeutic effect on stroke prevention is available so far. FXI inhibition could also be appealing for patients with other conditions, including end-stage renal disease, noncardioembolic stroke, or acute myocardial infarction, for which other phase 2 studies have been conducted. The balance between thromboprophylaxis and bleeding achieved by FXI inhibitors needs confirmation in large-scale phase 3 clinical trials powered for clinical end points. Several of such trials are ongoing or planned to define the role of FXI inhibitors in clinical practice and to clarify which FXI inhibitor may be most suited for each clinical indication. This article reviews the rationale, pharmacology, results of medium or small phase 2 studies, and future perspectives of drugs inhibiting FXI.