Warfarin Maintenance Dosing Patterns in Clinical Practice

Practical Suggestions for an Optimal Management of Vitamin K Antagonists: Italian Federation of Centers for the Diagnosis of Thrombotic Disorders and the Surveillance of the Antithrombotic Therapies (FCSA) Position Paper

In the era of direct oral anticoagulants, vitamin K antagonists retain a clinically relevant role in thrombotic disorders. In Italy, approximately 20% of the patients on anticoagulant therapies receives a VKA, in most cases warfarin. The optimal management of this drug is challenging and cannot disregard its intricate and unpredictable pharmacokinetic properties and patient's thrombotic and bleeding risk. Several clinical issues encountered during warfarin treatment are still unanswered and are tentatively addressed by physicians. In this regard, the Italian Federation of Centers for the diagnosis of thrombotic disorders and the Surveillance of the Antithrombotic therapies (FCSA) provides some experience-based good clinical practice's suggestions on the following topics: (1) how to start the anticoagulant treatment with warfarin and warfarin induction regimen; (2) how to manage a subtherapeutic INR value; (3) how to manage a supratherapeutic INR value in asymptomatic patients; and (4) how to manage the association of warfarin with interfering drugs.

Construction of warfarin population pharmacokinetics and pharmacodynamics model in Han population based on Bayesian method

The purpose of this paper is to study the genetic polymorphisms of related gene loci (CYP2C9*3, VKORC1-1639G > A) based on demographic and clinical factors, and use the maximum a posterior Bayesian method to construct a warfarin individualized dose prediction model in line with the Chinese Han population. Finally, the built model is compared and analyzed with the widely used models at home and abroad. In this study, a total of 5467 INR measurements are collected from 646 eligible subjects in our hospital, and the maximum a posterior Bayesian method is used to construct a warfarin dose prediction that conforms to the Chinese Han population on the basis of the Hamberg model. The model is verified and compared with foreign models. This study finds that body weight and concomitant use of amiodarone have a significant effect on the anticoagulant effect of warfarin. The model can provide an effective basis for individualized and rational dosing of warfarin in Han population more accurately. In the performance of comparison with different warfarin dose prediction models, the new model has the highest prediction accuracy, and the prediction percentage is as high as 72.56%. The dose predicted by the Huang model is the closest to the actual dose of warfarin. The population pharmacokinetics and pharmacodynamics model established in this study can better reflect the distribution characteristics of INR values after warfarin administration in the Han population, and performs better than the models reported in the literature.

Oral anticoagulant therapy in older adults

Patients aged ≥65 years not only account for the majority of patients with atrial fibrillation (AF) and venous thromboembolism (VTE), they are also at a higher risk of morbidity, mortality, and undertreatment than younger patients. Several age-related physiological changes with effects on drug pharmacokinetics/-dynamics and blood vessel fragility as well as the higher prevalence of geriatric conditions such as frailty, multimorbidity, polypharmacy, fall risk, dementia, and malnutrition make older persons more vulnerable to disease- and anticoagulation-related complications. Moreover, because older patients with AF/VTE are underrepresented in oral anticoagulation (OAC) trials, evidence on OAC in older adults with AF/VTE is mainly based on subgroup analyses from clinical trials and observational studies. A growing body of such limited evidence suggests that direct oral anticoagulants (DOACs) may be superior in terms of efficacy and safety compared to vitamin K antagonists in older persons with AF/VTE and that specific DOACs may have a differing risk-benefit profile. In this narrative review, we summarize the evidence on epidemiology of AF/VTE, impact of age-related physiological changes, efficacy/safety of OAC, specifically considering individuals with common geriatric conditions, and review OAC guideline recommendations for older adults with AF/VTE. We also propose a research agenda to improve the evidence basis on OAC older individuals with AF/VTE, including the conduct of advanced age-specific and pragmatic studies using less restrictive eligibility criteria and patient-reported health outcomes, in order to compare the effectiveness and safety of different DOACs, and investigate lower-dose regimens and optimal OAC durations in older patients.

Outcome of novel oral anticoagulant versus warfarin in frail elderly patients with atrial fibrillation: a systematic review and meta-analysis of retrospective studies

BACKGROUND

Frail patients with atrial fibrillation (AF) are thought to be at a higher risk for cerebral infarction and death than patients who are not frail, making preventive interventions important. Anticoagulants should be used in frailty patients with AF. However, there are limited data about anticoagulants in frail patients with AF. Therefore, we concucted this meta-analysis to find the best anticoagulation strategy.

METHODS

Systematic electronic searches were conducted on 4 July 2022 4 July 2022, in PubMed, Embase (Ovid), and Cochrane Library. Relevant and eligible cohort studies were included. A random-effects model was used to estimate the pooled Hazard ratio (HR) and 95% confidence intervals (CI). Furthermore, we performed a publication bias analysis and subgroup analysis to explore the source of heterogeneity.

RESULT

3 publications (10 cohorts, 188573 participants) met our inclusion criteria. The pooled analysis showed that ischemic strokes (HR: 0.75; 95%CI: 0.71 to 0.79; I2 = 60.2%), systemic embolism (HR: 0.75; 95%CI: 0.64 to 0.87; I  = 68.6%), major bleeding(HR: 0.76; 95%CI: 0.64 to 0.89; I2 = 97.4%), intracranial hemorrhage (HR: 0.57; 95%CI: 0.45 to 0.71; I2 = 54.6%) and cardiovascular death(HR: 0.61; 95%CI: 0.51 to 0.70; I2 = 83.2%) were lower in NOACs as compared with warfarin. Regarding gastrointestinal bleeding, meta-analysis showed no significant differences in the risk of gastrointestinal bleeding (HR: 0.97; 95%CI: 0.69 to 1.36; I2 = 95.9%).   .

CONCLUSION

NOAC was more effective and safety than warfarin in frail patients with AF.

Impact of Initial Warfarin Dosing on Time in Therapeutic Range for Postoperative Left Ventricular Assist Device Patients

ABSTRACT

Initial warfarin dosing and time in therapeutic range (TTR) are poorly characterized for early post-operative left ventricular assist device (LVAD) patients. This study evaluated TTR after LVAD implantation compared between patients receiving low-dose (<3 mg) and high-dose (≥3 mg) warfarin. This single-center, retrospective analysis included 234 LVAD patients who received warfarin within 5 days of implantation. The primary outcome was TTR during the 5 days following first international normalized ratio (INR) ≥2 compared between low-dose and high-dose groups. Secondary outcomes were hospital and intensive care unit length of stay, time to first INR ≥2, TTR after first INR ≥2, and reinitiation of parenteral anticoagulation. No difference in TTR was detected between warfarin groups (57.2% vs. 62.7%, P = 0.13). Multivariable analysis did not detect any factors predictive of TTR during the primary outcome timeframe, but age and body mass index were associated with the warfarin dose. The low-dose group received a mean warfarin dose of 1.9 mg (±0.64 mg), and the high dose group received 4.34 mg (±1.38 mg). Cohort TTR during the primary outcome timeframe was 60.5% and 56.5% for hospitalization. The low-dose group had longer intensive care unit length of stay, shorter time to therapeutic INR, and more frequently reinitiated parenteral anticoagulation. Patients with recent LVAD implantation are complex and have diverse warfarin sensitivity factors, which did not allow for optimal warfarin dose detection, although half of all patients received doses between 2.04 mg and 4.33 mg. Individualized dosing should be used, adjusting for patient-specific factors such as age, body mass index, and drug interactions.

Coagulation and Aging: Implications for the Anesthesiologist

Purpose of Review

This narrative review focuses on aging-related modifications in coagulation resulting in increased thromboembolic and hemorrhagic risk of the elderly. We further discuss the current evidence and emerging data relating the perioperative treatment of elderly patients with antithrombotic therapy.

Recent Findings

Relevant changes in all elements of the Virchow’s triad can be found with aging. Increased blood stasis due to immobility, progressive endothelial dysfunction with altered microcirculation, elevated concentrations of several coagulation factors, and increased platelet reactivity all lead to a procoagulant state. Elderly people are, therefore, commonly treated with oral anticoagulation and antiplatelet drugs. This antithrombotic therapy might be essentially causative for their increased bleeding risk.

Summary

Elderly patients are at increased risk for thromboembolism due to changes in the hemostatic system in combination with frailty and multimorbidity. Both the thromboembolic due to aging and bleeding risk due to antithrombotic therapy need special attention in the elderly surgical patients.

Antithrombotic therapy in the elderly and senile age: the consensus opinion of experts of the Russian Association of Gerontologists and Geriatricians and the National Society of Preventive Cardiology

В данном документе обсуждаются особенности АТТ у лиц пожилого и старческого возраста в различных клинических ситуациях.

Sex-influence on the time in therapeutic range (TTR) during oral anticoagulation with coumarin derivatives: Systematic review and meta-analysis

AIMS

We sought to investigate the association between sex and oral anticoagulation control employing coumarin derivatives.

METHODS

Electronic sources were MEDLINE, Biblioteca Virtual em Saúde (BVS), The Cumulative Index to Nursing and Allied Health Literature (CINAHL), EMBASE, Cochrane Central and Web of Science. Inclusion criteria were: observational and experimental studies; age ≥18 years; both sexes; treatment with any coumarin derivative for ≥3 months; any indication of long-term use; quality of oral anticoagulation measured by time in therapeutic range (TTR). The meta-analysis was developed with odds ratios (OR) for binary variables and mean differences (MD) for continuous variables, using random-effects models (DerSimonian and Laird) with 95% confidence intervals (CI).

RESULTS

Overall, 22 articles were selected, comprising 16 cohort studies, four cross-sectional studies and two clinical trials. The number of participants ranged from 110 to 104 505 (183 612; women: 45%). The main indication of oral anticoagulation was atrial fibrillation. Most studies reported the use of warfarin. In the meta-analysis, 15 studies were analysed using TTR as a binary variable (OR = 0.87; 95% CI = 0.78, 0.96; z = -2.75; P = .006.; I²  = 67%) and seven studies as a continuous variable (MD = -2.97; 95% CI = -4.80, -1.14; z = -3.19; P = .0014; I²  = 75%). The pooled estimates indicated that women were associated with lower TTR than men.

CONCLUSIONS

Our findings revealed an association between female sex and worse oral anticoagulation control. Further studies are needed with primary design to investigate sex-related factors influencing oral anticoagulation control with coumarin derivatives. Innovative strategies focused on women's health may be useful to improve patient-centred care.

The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Comprehensive Guidelines for the Management of Atrial Fibrillation

The Canadian Cardiovascular Society (CCS) atrial fibrillation (AF) guidelines program was developed to aid clinicians in the management of these complex patients, as well as to provide direction to policy makers and health care systems regarding related issues. The most recent comprehensive CCS AF guidelines update was published in 2010. Since then, periodic updates were published dealing with rapidly changing areas. However, since 2010 a large number of developments had accumulated in a wide range of areas, motivating the committee to complete a thorough guideline review. The 2020 iteration of the CCS AF guidelines represents a comprehensive renewal that integrates, updates, and replaces the past decade of guidelines, recommendations, and practical tips. It is intended to be used by practicing clinicians across all disciplines who care for patients with AF. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate recommendation strength and the quality of evidence. Areas of focus include: AF classification and definitions, epidemiology, pathophysiology, clinical evaluation, screening and opportunistic AF detection, detection and management of modifiable risk factors, integrated approach to AF management, stroke prevention, arrhythmia management, sex differences, and AF in special populations. Extensive use is made of tables and figures to synthesize important material and present key concepts. This document should be an important aid for knowledge translation and a tool to help improve clinical management of this important and challenging arrhythmia.

[The Effect of Increased Free Concentrations of Warfarin Due to Protein-binding Substitution in a Combination of Tolvaptan on the PT-INR]

We previously reported that tolvaptan may influence warfarin pharmacodynamics in vivo; however, the mechanism responsible for this influence was not clear. In this study, we investigated the drug-drug interactions between warfarin and tolvaptan by measuring warfarin blood concentrations in 18 patients who received warfarin therapy and in 24 who received warfarin+tolvaptan therapy. The free warfarin concentrations significantly increased in patients who were also receiving oral tolvaptan (p=0.04). In vitro albumin-binding experiments showed that the free warfarin concentrations significantly increased with the addition of tolvaptan, in a dose-dependent manner, through albumin-binding substitution (approximately 2.5 times). Both clinical and in vitro data showed that tolvaptan increased the unbound warfarin serum concentration. The prothrombin time-international normalized ratio (PT-INR) tended to increase within 2 weeks when tolvaptan was added at clinically used doses (p=0.14). Special attention is warranted in cases with a serum tolvaptan concentration of ≥125 ng/mL (≥7.5 mg/d) for at least 2 weeks following oral tolvaptan administration.

Current status of rivaroxaban in elderly patients with pulmonary embolism (Review)

Acute pulmonary embolism (PE) occurs with a high incidence rate in elderly patients, demonstrating complex clinical manifestations, as well as a difficult anticoagulant treatment strategy. Currently, there is limited understanding of the selection criteria for anticoagulant treatment in elderly patients with PE. In fact, the vitamin K antagonist warfarin, a commonly prescribed anticoagulant, has multiple disadvantages, including a narrow therapeutic range, unpredictable pharmacokinetics, multiple food and drug interactions and genetic polymorphisms resulting in poor response to this therapy; therefore, routine laboratory monitoring is required. Most elderly patients with PE fail to adhere to the treatment regimen or even discontinue it, and clinicians are equally hesitant to initiate oral anticoagulants in elderly patients with PE. This leads to a dilemma regarding the use of anticoagulation therapies and a worse prognosis for the patients. Rivaroxaban, a direct Xa factor inhibitor, has demonstrated considerable practical and clinical advantages, exhibits fast-start action pharmacokinetic and pharmacodynamic characteristics, and has an enhanced predictable anticoagulant effect with fewer drug-drug interactions. Based on randomized controlled trials and real-world clinical practice, rivaroxaban has also been recognized as a safe and effective anticoagulant, and these advantages have improved the therapeutic compliance of elderly patients with PE. Thus, this review focused on the current status of rivaroxaban treatment for elderly patients with PE, and described its significance in changing the current anticoagulation treatment regimens for patients. It is expected that rivaroxaban will become a good choice for the treatment of PE in elderly patients.

Sexual Dimorphism in Drug Metabolism and Pharmacokinetics

Background:

Sex and gender-based differences are observed well beyond the sex organs and affect several physiological and biochemical processes involved in the metabolism of drug molecules. It is essential to understand not only the sex and gender-based differences in the metabolism of the drug but also the molecular mechanisms involved in the regulation of drug metabolism for avoiding sex-related adverse effects of drugs in the human.

Method:

The articles on the sex and gender-based differences in the metabolism of drug molecules were retrieved from the Pub Med database. The articles were classified into the metabolism of the drug molecule, gene expression regulation of drug-metabolizing enzymes, the effect of sex hormones on the metabolism of drug, expression of drugmetabolizing enzymes, etc.

Result:

Several drug molecules are known, which are metabolized differently in males and females. These differences in metabolism may be due to the genomic and non-genomic action of sex hormones. Several other drug molecules still require further evaluation at the molecular level regarding the sex and gender-based differences in their metabolism. Attention is also required at the effect of signaling cascades associated with the metabolism of drug molecules.

Conclusion:

Sex and gender-based differences in the metabolism of drugs exist at various levels and it may be due to the genomic and non-genomic action of sex hormones. Detailed understanding of the effect of sex and related condition on the metabolism of drug molecules will help clinicians to determine the effective therapeutic doses of drugs dependingon the condition of patient and disease.

Why maximum tolerated dose?

A long-established approach to the pharmacological treatment of disease has been to start low and go slow. However, clinicians often prescribe up to maximum tolerated dose (MTD), especially when treating acute and more severe disease, without evidence to show that MTD is more likely to improve outcomes. Cardiovascular guidelines for some indications advocate MTD even in prevention, for example hypercholesterolaemia, without compelling evidence of better outcomes. This review explores the origins and potential problems of prescribing medications at MTD. Oral effective dose 50 (ED50) may be a useful guide for balancing efficacy and safety.

Algorithm for predicting low maintenance doses of warfarin using age and polymorphisms in genes CYP2C9 and VKORC1 in Brazilian subjects

Warfarin exhibits a wide variation in dose requirements. We sought to evaluate the association of polymorphisms CYP2C9*2 (rs1799853), CYP2C9*3 (rs1075910), and VKORC1-G1639A (rs9923231) and nongenetic factors with maintenance doses of warfarin <17.5 mg/week and to create an algorithm to predict drug sensitivity. This is a retrospective cohort study including 312 patients assisted at an anticoagulation clinic in Brazil. The mean age of participants was 60.4 ± 13.5 years and 59.9% were female. The logistic regression model included: age [odds ratio (OR) 1.03, 95% confidence interval (CI) 1.01-1.06], genotype VKORC1 AA (OR 31.61, 95% CI 11.20-100.15) and genotype CYP2C9 2/2, 2/3 or 3/3 (OR 16.48, 95% CI 3.37-81.79). The creation of our algorithm involved warfarin-experienced patients on stable doses, identifying factors associated with drug sensitivity. The validation of this algorithm allows its use in future populations to determine the initial dose distinguishing patients with dose requirements <17.5 mg and reducing time to achieve stable doses.

Non–Vitamin K Antagonist Oral Anticoagulants in the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) increases a patient's stroke risk four- to five-fold. Anticoagulation with the vitamin K antagonist (VKA) warfarin reduces the risk of stroke by 67%, but warfarin carries a significant risk of major bleeding and has unpredictable pharmacodynamics with a narrow therapeutic window, necessitating frequent monitoring of its anticoagulant effect. The non–vitamin K antagonist oral anticoagulants (NOACs) dabigatran, rivaroxaban, apixaban, and edoxaban provide more predictable anticoagulant activity than warfarin with a lower risk of major bleeding, and each is noninferior to warfarin for the prevention of stroke. All have earned regulatory approval in the past eight years. At least one of the NOACs is approved for use in all patients with AF, except those with mechanical valves and rheumatic mitral valve disease, for whom warfarin remains the only option. Recent clinical trials have shown that antithrombotic regimens including NOACs are safe and effective in patients with AF who need potent antiplatelet therapy.

Follow-up and management of valvular heart disease patients with prosthetic valve: a clinical practice guideline for Indian scenario

PURPOSE

Valvular heart disease (VHD) patients after prosthetic valve implantation are at risk of thromboembolic events. Follow-up care of patients with prosthetic valve has a paramount role in reducing the morbidity and mortality. Currently, in India, there is quintessential need to stream line the follow-up care of prosthetic valve patients. This mandates the development of a consensus guideline for the antithrombotic therapy in VHD patients post prosthetic valve implantation.

METHODS

A national level panel was constituted comprising 13 leading cardio care experts in India who thoroughly reviewed the up to date literature, formulated the recommendations, and developed the consensus document. Later on, extensive discussions were held on this draft and the recommendations in 8 regional meetings involving 79 additional experts from the cardio care in India, to arrive at a consensus. The final consensus document is developed relying on the available evidence and/or majority consensus from all the meetings.

RESULTS

The panel recommended vitamin K antagonist (VKA) therapy with individualized target international normalized ratio (INR) in VHD patients after prosthetic valve implantation. The panel opined that management of prosthetic valve complications should be personalized on the basis of type of complications. In addition, the panel recommends to distinguish individuals with various co-morbidities and attend them appropriately.

CONCLUSIONS

Anticoagulant therapy with VKA seems to be an effective option post prosthetic valve implantation in VHD patients. However, the role for non-VKA oral therapy in prosthetic valve patients and the safety and efficacy of novel oral anticoagulants in patients with bioprosthetic valve need to be studied extensively.

Optimizing quality care for the oral vitamin K antagonists (VKAs)

Vitamin K antagonists (VKAs) have been the only oral anticoagulants for decades. The management of anticoagulant therapy with VKA is challenging because of the intricate pharmacological properties of these agents. The success of VKA therapy depends on the quality of treatment that is ensured through continuing comprehensive communication and education. The educational program should address important issues of the VKA therapy such as beginning of treatment, pharmacological, dietary, and drug-drug interactions, as well as treatment temporary suspension during surgical interventions or invasive maneuvers. In addition, the initial and continuing patient education is of imperative importance. A major role in the educational process may be addressed by patient associations. The quality of treatment is better reached if patients are followed in anticoagulation clinics. Moreover, a federation of anticoagulation clinics may improve patient care through regular meetings to update knowledge on VKA treatment. Learning objectives of this paper is to allow readers to correctly approach patients starting VKA treatment, recognize possible pitfalls of treatment, and provide adequate solutions.

The Effect of Demographic Factors and VKORC1 1639 G>A Genotypes on Estimated Warfarin Maintenance Dose in Iranian Patients Under Warfarin Therapy

Warfarin is an anticoagulant that inhibits vitamin K-dependent clotting factors including factor (F) II, FVII, FIX and FX. Different factors can change the effect of this anticoagulant in clinic. Therefore we assessed impact of VKORC1 -1639 G>A polymorphism and demographic factors on required maintenance dose in Iranian patients under warfarin therapy. The study population included 95 patients with a mean age of 61.3 ± 12.6 years. Target INR range of 2-3 was considered for these patients. The frequency of VKORC1 -1639 G>A polymorphism was assessed by polymerase chain reaction-restriction length polymorphism (PCR-RFLP). Finally the obtain data were analyzed by SPSS software. Our study revealed that 30.5%, 49.5%, and 20% of the patients had VKORC1 (G/G), (G/A), and (A/A) genotypes, respectively. Carriers of VKORC1 G/G genotype required a higher warfarin dose as compared to A/A carriers (4.48 ± 1.32 and 2.7 ± 1.16 mg/day, respectively; P < 0.01). In addition, patients with higher age required lower warfarin therapeutic dose (r = - 0.3, P < 0.01). It seems that -1639 G>A polymorphism and demographic variables had significant effects on warfarin maintenance dose in Iranian patients under warfarin therapy.

Comparison of Warfarin Requirements in Post-cardiac Surgery Patients: Valve Replacement Versus Non-valve Replacement

INTRODUCTION

Anticoagulation with warfarin affects approximately 140,000 post-cardiac surgery patients every year, yet there remains limited published data in this patient population. Dosing remains highly variable due to intrinsic risk factors that plague cardiac surgery candidates and a lack of diverse literature that can be applied to those who have undergone a cardiac surgery alternative to heart valve replacement (HVR). In the present study, our aim was to compare the warfarin requirements between HVR and non-HVR patients.

METHODS

This was a single-center, retrospective study of post-cardiac surgery patients initiated on warfarin at Mayo Clinic Hospital, Rochester, from January 1st, 2013 to October 31st, 2016. The primary outcome was the maintenance warfarin dose at the earliest of discharge or warfarin day 10 between patients with HVR and non-HVR cardiac surgeries.

RESULTS

A total of 683 patients were assessed during the study period: 408 in the HVR group and 275 in the non-HVR group. The mean warfarin maintenance doses in the HVR and non-HVR groups were 2.55 mg [standard deviation (SD) 1.52] and 2.43 mg (SD 1.21), respectively (adjusted p = 0.65). A multivariable analysis was performed to adjust for gender, age, body mass index and drug interactions.

CONCLUSIONS

This was the largest study to evaluate warfarin dose requirements in post-cardiac surgery patients and is the first to compare warfarin requirements between HVR and non-HVR patients during the immediate post-operative period. Both groups had similar warfarin requirements, which supports expanding the initial warfarin dosing recommendations of the 9th edition Chest guideline to include non-HVR patients as well as HVR patients.

Effects of vitamin K epoxide reductase complex 1 gene polymorphisms on warfarin control in Japanese patients with left ventricular assist devices (LVAD)

PURPOSE

This study aimed to investigate relationships between times in therapeutic range (TTR) or warfarin sensitivity indexes (WSI) and VKORC1-1639G>A and CYP2C9 polymorphisms in patients with left ventricular assist devices (LVAD).

METHODS

Severe heart failure patients who received LVAD from January 1, 2013 to October 31, 2017 were recruited. Relationships between TTR or WSI and VKORC1-1639G>A and CYP2C9 gene polymorphisms were investigated immediately after LVAD implantation (period 1) and immediately prior to hospital discharge (period 2).

RESULTS

Among 54 patients, 31 (72.1%) had VKORC1-1639AA and CYP2C9*1/*1 (AA group) polymorphisms and 12 (27.9%) had VKORC1-1639GA and CYP2C9*1/*1 (GA group) polymorphisms. During period 1, mean prothrombin time-international normalized ratio (PT-INR) values were significantly higher in the AA group than in the GA group (2.21 vs. 2.05, p < 0.0001). Mean WSI values were 1.68-fold greater in the AA group than in the GA group (1.14 vs. 0.68, p < 0.0001). In addition, times below the therapeutic range (TBTR) in the GA group were significantly greater than in the AA group during period 1 (39.8 vs. 28.3%, p = 0.032), and insufficient PT-INR was more frequent in the GA group than in the AA group. However, mean PT-INR values during period 2 did not differ and no significant differences in TTR, TATR, and TBTR values were identified. In subsequent multivariable logistic regression analyses, the VKORC1-1639GA allele was significantly associated with insufficient anticoagulation.

CONCLUSION

Patients with the VKORC1-1639GA and CYP2C9*1/*1 alleles may receive insufficient anticoagulation therapy during the early stages after implantation of LVAD, and VKORC1-1639G>A and CYP2C9 genotyping may contribute to more appropriate anticoagulant therapy after implantation of LVAD.

Clotting-Factor Concentrations 5 Days After Discontinuation of Warfarin

BACKGROUND

The American Society of Regional Anesthesia and Pain Medicine guidelines recommend discontinuation of warfarin and an international normalized ratio (INR) of 1.2 or less before a neuraxial injection. The European and Scandinavian guidelines accept an INR of 1.4 or less. We evaluated INR and levels of clotting factors (CFs) II, VII, IX, and X 5 days after discontinuation of warfarin.

METHODS

Patients who discontinued warfarin for 5 days and had an INR of 1.4 or less had activities of factors II, VII, IX, and X measured. The primary outcome was the frequency of subjects with CF activities of less than 40%.

RESULTS

Twenty-three patients were studied; 21 (91%) had an INR of 1.2 or less. In these 21 patients, the median (interquartile range) activities of factors II, VII, IX, and X were 66% (52%-80%), 114% (95%-132%), 101% (84%-121%), and 55% (46%-63%), respectively. Ninety-five percent (99% confidence interval, 69%-99%) had CF activities of greater than 40%. The patient who did not CF activities greater than 40% had end-stage renal disease. Two subjects had an INR of greater than 1.2; the activities of factor II, VII, IX, and X were 37% and 46%, 89% and 105%, 66% and 78%, and 20% and 36%, respectively. Neither patient had CF activities of greater than 40%.

CONCLUSIONS

Based on 40% activity of CFs, patients with INRs of 1.2 or less can be considered to have adequate CFs to undergo neuraxial injections. The number of patients with an INR of 1.3 and 1.4 is too small to make conclusions.

Influence of Age on Warfarin Dose, Anticoagulation Control, and Risk of Hemorrhage

OBJECTIVE

We assessed the influence of age on warfarin dose, percentage time in target range (PTTR), and risk of major hemorrhage.

DESIGN

Warfarin users recruited into a large prospective inception cohort study were categorized into three age groups: young (younger than 50 yrs), middle aged (50-70 yrs), and elderly (older than 70 yrs). The influence of age on warfarin dose and PTTR was assessed using regression analysis; risk of major hemorrhage was assessed using proportional hazards analysis. Models were adjusted for demographic, clinical, and genetic factors.

SETTING

Two outpatient anticoagulation clinics.

PARTICIPANTS

A total of 1498 anticoagulated patients.

OUTCOMES

Warfarin dose (mg/day), PTTR, major hemorrhage.

RESULTS

Of the 1498 patients, 22.8% were young, 44.1% were middle aged, and 33.1% were elderly. After accounting for clinical and genetic factors, compared with young warfarin users, warfarin dose requirements were 10.6% lower among the middle aged and an additional 10.6% lower for the elderly. Compared with young patients, middle-aged and elderly patients spent more time in target international normalized ratio (INR) range (p<0.0001), despite having fewer INR assessments (p<0.0001). Compared with young warfarin users, absolute risk of hemorrhage was marginally higher among the middle aged (p=0.08) and significantly higher among the elderly (p=0.016). Compared with young warfarin users, after adjustment, the relative risk of hemorrhage increased by 31% for each age category (p=0.026).

CONCLUSIONS

In a real-world setting, despite achieving better anticoagulation control, elderly patients had a higher risk of major hemorrhagic events. As the population ages and the candidacy for oral anticoagulation increases, strategies that mitigate the elevated risk of hemorrhage need to be identified.

A review of drug-drug interactions in older HIV-infected patients

INTRODUCTION

The number of older HIV-infected people is growing due to increasing life expectancies resulting from the use of antiretroviral therapy (ART). Both HIV and aging increase the risk of other comorbidities, such as cardiovascular disease, osteoporosis, and some malignancies, leading to greater challenges in managing HIV with other conditions. This results in complex medication regimens with the potential for significant drug-drug interactions and increased morbidity and mortality. Area covered: We review the metabolic pathways of ART and other medications used to treat medical co-morbidities, highlight potential areas of concern for drug-drug interactions, and where feasible, suggest alternative approaches for treating these conditions as suggested from national guidelines or articles published in the English language. Expert commentary: There is limited evidence-based data on ART drug interactions, pharmacokinetics and pharmacodynamics in the older HIV-infected population. Choosing and maintaining effective ART regimens for older adults requires consideration of side effect profile, individual comorbidities, interactions with concurrent prescriptions and non-prescription medications and supplements, dietary patterns with respect to dosing, pill burden and ease of dosing, cost and affordability, patient preferences, social situation, and ART resistance history. Practitioners must remain vigilant for potential drug interactions and intervene when there is a potential for harm.

Targeted Thromboelastographic (TEG) Blood Component and Pharmacologic Hemostatic Therapy in Traumatic and Acquired Coagulopathy

Trauma-induced coagulopathy (TIC) is a recently described condition which traditionally has been diagnosed by the common coagulation tests (CCTs) such as prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), platelet count, and fibrinogen levels. The varying sensitivity and specificity of these CCTs have led trauma coagulation researchers and clinicians to use Viscoelastic Tests (VET) such as Thromboelastography (TEG) to provide Targeted Thromboelastographic Hemostatic and Adjunctive Therapy (TTHAT) in a goal directed fashion to those trauma patients in need of hemostatic resuscitation. This review describes the utility of VETs, in particular, TEG, to provide TTHAT in trauma and acquired non-trauma-induced coagulopathy.

Impact of gender on event rates at 1 year in patients with newly diagnosed non-valvular atrial fibrillation: contemporary perspective from the GARFIELD-AF registry

OBJECTIVES

Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) explored the impact of gender, risk factors and anticoagulant (AC) treatment on 1-year outcomes in patients with non-valvular atrial fibrillation (NVAF).

DESIGN

GARFIELD-AF is a prospective non-interventional registry.

SETTING

Investigator sites (n=1048) are representative of the care settings/locations in each of the 35 countries.

PARTICIPANTS

Patients ≥18yrs with newly diagnosed (≤6 weeks' duration) NVAF and ≥1 investigator-determined stroke risk factors.

MAIN OUTCOME MEASURES

Event rates per 100 person-years were estimated from the Poisson model and HRs and 95% CIs calculated.

RESULTS

Of 28 624 patients (women 44.4%; men 55.6%) enrolled, there were more elderly (≥75 years) women (46.9%) than men (30.4%). All-cause mortality rates per 100 person-years (95% CI) for women and men were 4.48 (4.12 to 4.87) and 4.04 (3.74 to 4.38), respectively, stroke/systemic embolism (SE) (1.62 (1.41 to 1.87) and 1.17 (1.01 to 1.36)) and major bleeding (0.93 (0.78 to 1.13) and 0.79 (0.66 to 0.95)). After adjustment for baseline risk factors in treated and untreated patients, HRs (95% CI) for women (relative to men) for stroke/SE rates were 1.3-fold higher in women (HR 1.30 (1.04 to 1.63)), and similar for major bleeding (1.13 (0.85 to 1.50)) and all-cause mortality (1.05 (0.92 to 1.19)). Antithrombotic treatment patterns in men and women were almost identical. 63.8% women and 62.9% men received AC± antiplatelets. Relative to no AC treatment, the reduction in stroke/SE rates with AC treatment was greater (p=0.01) in men (HR 0.45 (0.33 to 0.61)) than women 0.77 (0.57 to 1.03). All-cause mortality reduction with AC treatment was similar (women: 0.65 (0.54 to 0.77); men: 0.57 (0.48 to 0.68)). The risk of major bleeding when treated with AC versus no AC was 2.33 (1.41 to 3.84) in men and 1.86 (1.16 to 2.99) in women (p value=0.53).

CONCLUSIONS

Women have a higher risk of stroke/SE and the reduction in stroke/SE events rates with AC treatment is less in women than in men.

TRIAL REGISTRATION NUMBER

NCT01090362.

Age-stratified outcome of a genotype-guided dosing algorithm for acenocoumarol and phenprocoumon

Essentials The EU-PACT trial was used to investigate age on the interaction between coumarins and genotype. The results support the use of genotype-guided dosing for phenprocoumon in patients < 75 years. For patients ≥ 75 years the phenprocoumon algorithm should be revised and further tested. No influence of comorbidities and co-current drug use was found that could explain the differences.

SUMMARY

Background Age seemed to affect the interaction between coumarins and genotype in the acenocoumarol and phenprocoumon arm of the European Pharmacogenetics of Anticoagulant Therapy (EU-PACT) trial. Objectives To investigate the effect of genotype-guided dosing stratified by age and the potential factors causing a difference. Patients/Methods Data from the acenocoumarol/phenprocoumon arm of the EU-PACT trial were used. The percentages of time below the therapeutic range, time above the therapeutic range and time in the therapeutic range (TTR) during the initial 12 weeks of therapy were compared between the genotype-guided group and the control group among younger (< 75 years) and older (≥ 75 years) patients by the use of independent t-tests, and adjusted for sex, height, weight and co-medications by the use of linear regression. Results Among younger phenprocoumon users, TTR during the first 12 weeks in the genotype-guided group (n = 55) was 9.5% (95% confidence interval [CI] 1.3 to 17.8) higher than in the control group (n = 63), with a remarkably lower percentage of time above this range (difference: - 9.6%, 95% CI - 19.0 to - 0.2) and a similar time below this range. Older patients dosed by the genotype-guided algorithm (n = 24) spent more time above the range (difference: 27.5%, 95% CI 12.9 to 42.0). For acenocoumarol users, there were no significant differences between the genotype-guided and control groups for most outcomes, except for a lower percentage of time below the range among older patients. Conclusions The genotype-guided algorithm for phenprocoumon in the EU-PACT trial benefitted younger patients more, but for older patients the algorithm needs to be revised and tested in further research.

Comparison of the therapeutic dose of warfarin in HIV-infected and HIV-uninfected patients: a study of clinical practice

BACKGROUND

People infected with HIV are prone to venous thrombosis. Treatment of thrombosis is primarily with warfarin. No studies have addressed the effects of HIV infection on warfarin dose. The aims of this study were to determine whether the therapeutic dose of warfarin and induction time to therapeutic dose in HIV-infected patients differ from that in HIV-uninfected patients.

METHODS

A prospective and retrospective descriptive study of induction time to therapeutic warfarin dose, as well as of ambulant therapeutic warfarin dose, was performed. HIV-infected and HIV-uninfected patients being treated after deep venous thrombosis with or without pulmonary embolism were compared. Sex and use of antiretroviral drugs (ARVs) were also compared in the groups.

RESULTS

234 patients were entered into the study. Induction time to therapeutic warfarin dose did not differ between the 2 groups. The mean therapeutic dose of warfarin was higher in the HIV-infected than the HIV-uninfected group: 6.06 vs 5.72 mg/day, but this was not statistically significant (p=0.29). There was no difference in therapeutic warfarin dose between ARV-naïve groups-HIV-uninfected and HIV-infected patients not on ARVs.

CONCLUSIONS

There appears to be little effect of HIV infection on warfarin dosing. Warfarin therapy should be administered conventionally in HIV-infected patients.

Warfarin Dose Model for the Prediction of Stable Maintenance Dose in Indian Patients

The main aim of this study was to screen various genetic and nongenetic factors that are known to alter warfarin response and to generate a model to predict stable warfarin maintenance dose for Indian patients. The study comprised of 300 warfarin-treated patients. Followed by extensive literature review, 10 single-nucleotide polymorphisms, that is, VKORC1-1639 G>A (rs9923231), CYP2C9*2 (rs1799853), CYP2C9*3 (rs1057910), FVII R353Q (rs6046), GGCX 12970 C>G (rs11676382), CALU c.*4A>G (rs1043550), EPHX1 c.337T>C (rs1051740), GGCX: c.214+597G>A (rs12714145), GGCX: 8016G>A (rs699664), and CYP4F2 V433M (rs2108622), and 5 nongenetic factors, that is, age, gender, smoking, alcoholism, and diet, were selected to find their association with warfarin response. The univariate analysis was carried out for 15 variables (10 genetic and 5 nongenetic). Five variables, that is, VKORC1-1639 G>A, CYP2C9*2, CYP2C9*3, age, and diet, were found to be significantly associated with warfarin response in univariate analysis. These 5 variables were entered in stepwise and multiple regression analysis to generate a prediction model for stable warfarin maintenance dose. The generated model scored R² of .67, which indicates that this model can explain 67% of warfarin dose variability. The generated model will help in prescribing more accurate warfarin maintenance dosing in Indian patients and will also help in minimizing warfarin-induced adverse drug reactions and a better quality of life in these patients.

Atrial fibrillation in women: treatment

Sex-specific differences in the epidemiology, pathophysiology, presentation, prognosis, and treatment of atrial fibrillation (AF) are increasingly recognized. Women with AF generally experience worse symptoms, poorer quality of life, and have higher risk of stroke and death than men with AF. Effective treatment of the arrhythmia in women is critical to reduce the rate of adverse events. We review the current evidence on sex-specific differences in the utilization and outcomes of treatments for AF, including rate-control and rhythm-control strategies, and stroke-prevention therapy. In addition, we provide a critical evaluation of potential disparities and biases in health-care use that might be associated with differences in the outcomes between women and men. We underscore current knowledge gaps that need to be addressed in future studies to improve the management of AF in women. In particular, we suggest several strategies to produce high-quality evidence from randomized clinical trials for women with AF.

An expanded pharmacogenomics warfarin dosing table with utility in generalised dosing guidance

Pharmacogenomics (PGx) guided warfarin dosing, using a comprehensive dosing algorithm, is expected to improve dose optimisation and lower the risk of adverse drug reactions. As a complementary tool, a simple genotype-dosing table, such as in the US Food and Drug Administration (FDA) Coumadin drug label, may be utilised for general risk assessment of likely over- or under-anticoagulation on a standard dose of warfarin. This tool may be used as part of the clinical decision support for the interpretation of genetic data, serving as a first step in the anticoagulation therapy decision making process. Here we used a publicly available warfarin dosing calculator (www.warfarindosing.org) to create an expanded gene-based warfarin dosing table, the CPMC-WD table that includes nine genetic variants in CYP2C9, VKORC1, and CYP4F2. Using two datasets, a European American cohort (EUA, n=73) and the Quebec Warfarin Cohort (QWC, n=769), we show that the CPMC-WD table more accurately predicts therapeutic dose than the FDA table (51 % vs 33 %, respectively, in the EUA, McNemar's two-sided p=0.02; 52 % vs 37 % in the QWC, p<1×10(-6)). It also outperforms both the standard of care 5 mg/day dosing (51 % vs 34 % in the EUA, p=0.04; 52 % vs 31 % in the QWC, p<1×10(-6)) as well as a clinical-only algorithm (51 % vs 38 % in the EUA, trend p=0.11; 52 % vs 45 % in the QWC, p=0.003). This table offers a valuable update to the PGx dosing guideline in the drug label.

From left bundle branch block to Icelandic whales: the multiple perils of atrial fibrillation management in the elderly

We present the case of an elderly woman which demonstrates how AF therapy in aged individuals is particularly challenging for the presence of complex conditions. The rhythm- or the rate control strategy must be carefully chosen based on individual risk profile. Oral anticoagulant therapy must be wisely managed to maximize benefits-in terms of stroke and dementia control-and to reduce complications.

Intestinal toxicity of oral warfarin intake in rats

Though warfarin is extensively used in the prevention and treatment of thromboembolic processes in humans, adverse effects of warfarin therapy have been recognized. Intestinal hemorrhage is one of the hazards of anticoagulant therapy, but the mechanisms of warfarin toxicity are virtually unknown. In this work, the effects of 30 days oral warfarin (0.35 mg/l and 3.5 mg/l) intake on rat's gut were examined. Both doses resulted in prolongation of prothrombin time. Systemic effects of higher warfarin dose (increases in plasma AST, proteinuria, hematuria, changes in peripheral blood hematological parameters) were seen. Warfarin intake resulted in histologically evident tissue damage, leukocyte infiltration and intestinal inflammation [increases in myeloperoxidase activity, malondialdehyde content, superoxide dismutase and catalase activity, proinflammatory cytokine (IFN-γ, IL-17) concentrations in intestinal homogenates]. In contrast, suppression of gut-draining mesenteric lymph node (MLN) cell activity [proliferation responsiveness, production of IFN-γ and IL-17 to T lymphocyte mitogen Concanavalin A stimulation] was noted. Inhibition of regulatory cytokine IL-10 production by MLN cells, suggests commitment of MLN to the suppression of all inflammatory activities and creation of the microenvironment which is non-permissive for induction of potentially harmful immune response. These novel findings indicate the need of staying alert for (adverse) effects of warfarin therapy.

North American Thrombosis Forum, AF Action Initiative Consensus Document

The North American Thrombosis Forum Atrial Fibrillation Action Initiative consensus document is a comprehensive yet practical briefing document focusing on stroke and bleeding risk assessment in patients with atrial fibrillation, as well as recommendations regarding anticoagulation options and management. Despite the breadth of clinical trial data and guideline recommendation updates, many clinicians continue to struggle to synthesize the disparate information available. This problem slows the uptake and utilization of updated risk prediction tools and adoption of new oral anticoagulants. This document serves as a practical and educational reference for the entire medical community involved in the care of patients with atrial fibrillation.

Mechanism of Drug-Drug Interactions Between Warfarin and Statins

The anticoagulant drug warfarin and the lipid-lowering statin drugs are commonly co-administered to patients with cardiovascular diseases. Clinically significant drug-drug interactions (DDIs) between these drugs have been recognized through case studies for many years, but the biochemical mechanisms causing these interactions have not been explained fully. Previous theories include kinetic alterations in cytochrome P-450-mediated drug metabolism or disturbances of drug-protein binding, leading to anticoagulant activity of warfarin; however, neither the enantioselective effects on warfarin metabolism nor the potential disruption of drug transporter function have been well investigated. This study investigated the etiology of the DDIs between warfarin and statins. Liquid chromatography-mass spectrometry methods were developed and validated to quantify racemic warfarin, 6 of its hydroxylated metabolites, and pure enantiomers of warfarin; these methods were applied to study the role of different absorption, distribution, metabolism, and excretion properties, leading to DDIs. Plasma protein binding displacement of warfarin was performed in the presence of statins using equilibrium dialysis method. Substrate kinetics of warfarin and pure enantiomers were performed with human liver microsomes to determine the kinetic parameters (Km and Vmax) for the formation of all 6 hydroxywarfarin metabolites, inhibition of warfarin metabolism in the presence of statins, was determined. Uptake transport studies of warfarin were performed using overexpressing HEK cell lines and efflux transport using human adenocarcinoma colonic cell line cells. Fluvastatin significantly displaced plasma protein binding of warfarin and pure enantiomers; no other statin resulted in significant displacement of warfarin. All the statins that inhibited the formation of 10-hydroxywarfarin, atorvastatin, pitavastatin, and simvastatin were highly potent compared to other statins; in contrast, only fluvastatin was found to be a potent inhibitor of formation of 7-hydroxy warfarin. Uptake and efflux drug transporters do not play any role in these DDIs. The results showed that DDIs between warfarin and statins are primarily caused by cytochrome P-450 inhibition.

Meta-analysis of Randomized Controlled Trials of Genotype-Guided vs Standard Dosing of Warfarin

BACKGROUND

Warfarin is a widely prescribed anticoagulant, and its effect depends on various patient factors including genotypes. Randomized controlled trials (RCTs) comparing genotype-guided dosing (GD) of warfarin with standard dosing have shown mixed efficacy and safety outcomes. We performed a meta-analysis of all published RCTs comparing GD vs standard dosing in adult patients with various indications of warfarin use.

METHODS

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and relevant references for English language RCTs (inception through March 2014). We performed the meta-analysis using a random effects model.

RESULTS

Ten RCTs with a total of 2,505 patients were included in the meta-analysis. GD compared with standard dosing resulted in a similar % time in therapeutic range (TTR) at ≤ 1 month follow-up (39.7% vs 40.2%; mean difference [MD], -0.52 [95% CI, -3.15 to 2.10]; P = .70) and higher % TTR (59.4% vs 53%; MD, 6.35 [95% CI, 1.76-10.95]; P = .007) at > 1 month follow-up, a trend toward lower risk of major bleeding (risk ratio, 0.46 [95% CI, 0.19-0.1.11]; P = .08) at ≤ 1 month follow-up and lower risks of major bleeding (0.34 [95% CI, 0.16-0.74], P = .006) at > 1-month follow-up, and shorter time to maintenance dose (TMD) (24.6 days vs 34.1 days; MD, -9.54 days [95% CI, -18.10 to -0.98]; P = .03) at follow-up but had no effects on international normalized ratio [INR] > 4.0, nonmajor bleeding, thrombotic outcomes, or overall mortality.

CONCLUSIONS

In the first month of genotype-guided warfarin therapy, compared with standard dosing, there were no improvements in % TTR, INR > 4.0, major or minor bleeding, thromboembolism, or all-cause mortality. There was a shorter TMD, and, after 1 month, improved % TTR and major bleeding incidence, making this a cost-effective strategy in patients requiring longer anticoagulation therapy.

VKORC1 -1639G/A and 1173 C/T Genetic Polymorphisms Influence Individual Differences in Warfarin Maintenance Dose

OBJECTIVE

In this study, we investigated two VKORC1 gene polymorphisms, -1639G/A and 1173C/T, for effects on warfarin maintenance dosage in valvular heart disease (VHD) patients after cardiac valve replacement (CVR).

METHODS

A total of 219 VHD patients receiving warfarin therapy after CVR surgery were recruited to this study between June 2010 and December 2013. Basic clinical data, prothrombin time, warfarin maintenance dose, and blood samples were collected from all patients. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses were used to analyze the VKORC1 -1639G/A and 1173C/T polymorphisms. SPSS version 19.0 software was used for statistical analysis of the data.

RESULTS

Patients with either the AG+or GG genotype (n=32) of the VKORC1 -1639G/A polymorphism required a significantly higher warfarin dose compared to patients with the AA genotype (n=187) (4.36±1.03 mg/day vs. 2.95±0.94 mg/day; p<0.001). Similarly, patients carrying the CT genotype (n=28) of the VKORC1 1173C/T polymorphism also required a significantly higher warfarin dose compared to those with the TT genotype (n=191) (4.19±0.99 mg/day vs. 3.00±0.94 mg/day; p<0.001). Linear regression analysis showed that gender, age, weight, and VKORC1 -1639G/A and 1173C/T polymorphisms were correlated with individual differences in warfarin maintenance dose (all p<0.05).

CONCLUSION

We present evidence that the two VKORC1 polymorphisms, -1639G/A and 1173C/T, are key genetic factors influencing individual differences in warfarin maintenance dose in VHD patients who underwent CVR. Gender, age, and weight also independently correlated with warfarin maintenance dose.

Epidemiology, diagnosis, and management of atrial fibrillation in women

Atrial fibrillation (AF) is the most common arrhythmia and has become a serious public health problem. Moreover, epidemiological data demonstrate that incidence and prevalence of AF are increasing. Several differences in epidemiological patterns, clinical manifestations, and incidence of stroke have been reported between AF in women and in men, particularly in elderly women. Elderly women have higher blood pressure than men and a higher prevalence of heart failure with preserved ejection fraction, both independent risk factors for stroke. On the basis of the evidence on the higher stroke risk among AF in women, recently, female sex has been accepted as a risk factor for stroke and adopted to stratify patients, especially if they are not at high risk for stroke. This review focuses on available evidence on sex differences in AF patients, and examines factors contributing to different stroke risk, diagnosis, and prognosis of arrhythmia in women, with the aim to provide an analysis of the available evidence.

Brain and kidney, victims of atrial microembolism in elderly hospitalized patients? Data from the REPOSI study

BACKGROUND

It is well known that atrial fibrillation (AF) and chronic kidney disease (CKD) are associated with a higher risk of stroke, and new evidence links AF to cognitive impairment, independently from an overt stroke (CI). Our aim was to investigate, assuming an underlying role of atrial microembolism, the impact of CI and CKD in elderly hospitalized patients with AF.

METHODS

We retrospectively analyzed the data collected on elderly patients in 66 Italian hospitals, in the frame of the REPOSI project. We analyzed the clinical characteristics of patients with AF and different degrees of CI. Multivariate logistic analysis was used to explore the relationship between variables and mortality.

RESULTS

Among the 1384 patients enrolled, 321 had AF. Patients with AF were older, had worse CI and disability and higher rates of stroke, hypertension, heart failure, and CKD, and less than 50% were on anticoagulant therapy. Among patients with AF, those with worse CI and those with lower estimated glomerular filtration rate (eGFR) had a higher mortality risk (odds ratio 1.13, p=0.006). Higher disability levels, older age, higher systolic blood pressure, and higher eGFR were related to lower probability of oral anticoagulant prescription. Lower mortality rates were found in patients on oral anticoagulant therapy.

CONCLUSIONS

Elderly hospitalized patients with AF are more likely affected by CI and CKD, two conditions that expose them to a higher mortality risk. Oral anticoagulant therapy, still underused and not optimally enforced, may afford protection from thromboembolic episodes that probably concur to the high mortality.

Lack of clinical pharmacodynamic and pharmacokinetic drug-drug interactions between warfarin and the antisense oligonucleotide mipomersen

Mipomersen is a second-generation antisense oligonucleotide indicated as an adjunct therapy for homozygous familial hypercholesterolemia (HoFH). Warfarin is commonly prescribed for a variety of cardiac disorders in homozygous familial hypercholesterolemia population, and concurrent use of warfarin and mipomersen is likely. This open-label, single-sequence 2-period phase 1 study in healthy subjects evaluated the potential drug-drug interactions between mipomersen and warfarin. The subjects received a single oral 25 mg dose of warfarin alone on day 1, and after a 7-day washout period, received 200 mg mipomersen alone subcutaneously every other day on days 8-12, and received both concurrently on day 14. Coadministration of mipomersen did not change the pharmacodynamics (international normalized ratio, prothrombin time, and activated partial thromboplastin time) and pharmacokinetics (PK) of warfarin. There were no clinically significant changes in the PK of mipomersen with concurrent administration of warfarin. There were no events indicative of an increase in bleeding tendency when warfarin was coadministered with mipomersen, and the adverse event profile of mipomersen did not appear to be altered in combination with warfarin, as compared with that of the respective reference treatment. The combination of these 2 medications appeared to be safe and well tolerated. These results suggest that the dosage adjustment of warfarin or mipomersen is not expected to be necessary with coadministration.