Prevalence of markers of heart failure in patients with atrial fibrillation and the effects of ximelagatran compared to warfarin on the incidence of morbid and fatal events: a report from the SPORTIF III and V trials.

BACKGROUND: Patients with atrial fibrillation (AF) who also have heart failure have a worse outcome but the diagnosis of heart failure is often missed. AIM: To compare the effects of warfarin and ximelagatran on morbidity and mortality in patients with AF with and without markers of heart failure. METHODS AND RESULTS: Data for 7329 patients from two randomised controlled trials were merged. Treatment with loop diuretics or the presence of left ventricular dysfunction, were used as markers of possible heart failure. The 3555 (49%) patients with markers of heart failure had higher composite event rates on warfarin (10.81% per year [py] [95% CI 9.59 to 12.13]) compared to the 3774 (51%) patients without markers of heart failure (4.18% py [95% CI 3.44 to 5.01]). The composite event rate was lower on ximelagatran overall (6.18% py [95% CI 5.51 to 6.89] versus 7.34% py [95% CI 6.63 to 8.10] on warfarin; P=0.0219 for the difference) with similar effects in each trial and in patients with and without markers of heart failure, mainly due to fewer heart-failure events (hazard ratio 0.69 [95% CI 0.54 to 0.87]; P<0.001). CONCLUSIONS: Patients with markers of heart failure, even if the diagnosis is not well established, are at increased risk of thromboembolic events and might be targeted for more effective antithrombotic therapy. This might include patients in sinus rhythm as well as AF.

Effect of hypertension on anticoagulated patients with atrial fibrillation.

AIM: To test the hypothesis that stroke and systemic embolic events (SEE) in the Stroke Prevention using an ORal Thrombin Inhibitor in atrial Fibrillation (SPORTIF) III and V trials were related to blood pressure, and that differences in event rates (stroke and SEE, bleeding) could also be related to the degree of hypertension. METHODS AND RESULTS: A cross-sectional, longitudinal analysis was conducted, using data from the SPORTIF III and V trials. Results showed an increasing rate of stroke and SEE with increasing quartiles of systolic blood pressure (SBP) in AF patients. For the top quartile of SBP compared with the lowest quartile, the hazard ratio (HR) for stroke and SEE was 1.83 (95% confidence intervals [CI]: 1.22-2.74), whereas mortality was lower in the top quartile (HR 0.64; 95% CI: 0.49-0.83). In the combined SPORTIF III and V cohort, the event rate for stroke/SEE increased markedly at mean SBP of > 140 mmHg. There was no relationship between bleeding and quartiles of BP. The proportion of subjects with mean systolic BP > or = 140 mmHg was 35.8% (1220/3407) in SPORTIF III and 20.6% (807/3922) in SPORTIF V (P < 0.0001). CONCLUSION: Hypertension contributes to increased stroke and SEE in AF. Event rates markedly increase at SBP levels of > or = 140 mmHg. The higher stroke rates observed in SPORTIF III compared with SPORTIF V may be related to the greater proportion of subjects with SBP > or = 140 mmHg during the trial.

Population pharmacokinetics of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran, in atrial fibrillation patients receiving long-term anticoagulation therapy.

BACKGROUND: Ximelagatran is an oral direct thrombin inhibitor for the prevention of thromboembolic disease. After oral administration, ximelagatran is rapidly absorbed and bioconverted to its active form, melagatran. OBJECTIVE: To characterise the pharmacokinetics of melagatran in patients with nonvalvular atrial fibrillation (NVAF) receiving long-term treatment for prevention of stroke and systemic embolic events. METHODS: A population pharmacokinetic model was developed based on data from three phase II studies (1177 plasma concentration observations in 167 patients, treated for up to 18 months) and confirmed by including data from two phase III studies (8702 plasma concentration observations in 3188 patients, treated for up to 24 months). The impact of individualised dosing on pharmacokinetic variability was evaluated by simulations of melagatran concentrations based on the pharmacokinetic model. RESULTS: Melagatran pharmacokinetics were consistent across the studied doses and duration of treatment, and were described by a one-compartment model with first-order absorption and elimination. Clearance of melagatran was correlated to creatinine clearance, which was the most important predictor of melagatran exposure (explained 54% of interpatient variance in clearance). Total variability (coefficient of variation) in exposure was 45%; intraindividual variability in exposure was 23%. Concomitant medication with the most common long-term used drugs in the study population had no relevant influence on melagatran pharmacokinetics. Simulations suggested that dose adjustment based on renal function or trough plasma concentration had a minor effect on overall pharmacokinetic variability and the number of patients with high melagatran exposure. CONCLUSION: The pharmacokinetics of melagatran in NVAF patients were predictable, and consistent with results from previously studied patient populations. Dose individualisation was predicted to have a low impact on pharmacokinetic variability, supporting the use of a fixed-dose regimen of ximelagatran for long-term anticoagulant therapy in the majority of NVAF patients.

Ximelagatran vs warfarin for stroke prevention in patients with nonvalvular atrial fibrillation: a randomized trial.

CONTEXT: In patients with nonvalvular atrial fibrillation, warfarin prevents ischemic stroke, but dose adjustment, coagulation monitoring, and bleeding limit its use. OBJECTIVE: To compare the efficacy of the oral direct thrombin inhibitor ximelagatran with warfarin for prevention of stroke and systemic embolism. DESIGN, SETTING, AND PARTICIPANTS: Double-blind, randomized, multicenter trial (2000-2001) conducted at 409 North American sites, involving 3922 patients with nonvalvular atrial fibrillation and additional stroke risk factors. INTERVENTIONS: Adjusted-dose warfarin (aiming for an international normalized ratio [INR] 2.0 to 3.0) or fixed-dose oral ximelagatran, 36 mg twice daily. MAIN OUTCOME MEASURES: The primary end point was all strokes (ischemic or hemorrhagic) and systemic embolic events. The primary analysis was based on demonstrating noninferiority within an absolute margin of 2.0% per year according to the intention-to-treat model. RESULTS: During 6405 patient-years (mean 20 months) of follow-up, 88 patients experienced primary events. The mean (SD) INR with warfarin (2.4 [0.8]) was within target during 68% of the treatment period. The primary event rate with ximelagatran was 1.6% per year and with warfarin was 1.2% per year (absolute difference, 0.45% per year; 95% confidence interval, -0.13% to 1.03% per year; P<.001 for the predefined noninferiority hypothesis). When all-cause mortality was included in addition to stroke and systemic embolic events, the rate difference was 0.10% per year (95% confidence interval, -0.97% to 1.2% per year; P = .86). There was no difference between treatment groups in rates of major bleeding, but total bleeding (major and minor) was lower with ximelagatran (37% vs 47% per year; 95% confidence interval for the difference, -14% to -6.0% per year; P<.001). Serum alanine aminotransferase levels rose to greater than 3 times the upper limit of normal in 6.0% of patients treated with ximelagatran, usually within 6 months and typically declined whether or not treatment continued; however, one case of documented fatal liver disease and one other suggestive case occurred. CONCLUSIONS: The results establish the efficacy of fixed-dose oral ximelagatran without coagulation monitoring compared with well-controlled warfarin for prevention of thromboembolism in patients with atrial fibrillation requiring chronic anticoagulant therapy, but the potential for hepatotoxicity requires further investigation.

Effects of the oral direct thrombin inhibitor ximelagatran on p-selectin expression and thrombin generation in atrial fibrillation.

This study investigated the pharmacodynamic effects of the oral direct thrombin inhibitor ximelagatran on platelet activation and thrombin generation in patients with nonvalvular atrial fibrillation. Using an open, group-matched study design, the effects of ximelagatran (36 mg twice daily for 5 days) were studied in 12 patients with permanent nonvalvular atrial fibrillation and in 12 healthy controls. After ximelagatran for 5 days, elevated platelet P-selectin expression in atrial fibrillation patients was lowered to that during coumarin treatment or in controls but had no effect in control subjects. Using the endogenous thrombin potential as a marker, ximelagatran decreased and delayed thrombin generation in both groups. In conclusion, direct thrombin inhibition with ximelagatran reduced elevated platelet P-selectin expression and inhibited thrombin generation.

Consistent pharmacokinetics of the oral direct thrombin inhibitor ximelagatran in patients with nonvalvular atrial fibrillation and in healthy subjects.

OBJECTIVE: To investigate the influence of nonvalvular atrial fibrillation (NVAF) on the pharmacokinetic (PK) properties of the oral direct thrombin inhibitor ximelagatran and its active form, melagatran. METHODS: In an open study, 12 patients with persistent NVAF and 12 age- and gender-matched, healthy control subjects received a 10-min intravenous (i.v.) infusion of 2.66 mg melagatran followed by oral ximelagatran, 36 mg twice daily, for the subsequent five study days. Plasma and urine samples for PK analyses were collected after i.v. and single and repeated oral dosing. RESULTS: The oral absorption of ximelagatran was rapid, and maximum plasma concentrations of ximelagatran (Cmax) were achieved at about 1 h post-dosing. There were no differences between NVAF patients and controls for the area under the plasma concentration versus time curve, Cmax, half-life (t1/2), or bioavailability (F) of melagatran after oral dosing with ximelagatran. The Cmax of melagatran, formed by the rapid bioconversion of ximelagatran, occurred approximately 3 h post-dosing. The geometric means of the t1/2 for melagatran were 4.0 h and 4.2 h for the first and last doses, respectively, in patients, and 3.5 h and 3.7 h, respectively, in controls. Geometric means of F of melagatran following oral administration of ximelagatran were 22% and 24% for the first and last doses, respectively, in patients and 21% and 23%, respectively, in controls. Approximately 80% of the i.v. dose of melagatran was excreted in urine in patients and in controls. CONCLUSION: The PK properties of oral ximelagatran and i.v. melagatran in elderly patients with NVAF are consistent with those in matched, healthy controls.

Ximelagatran versus warfarin for stroke prevention in patients with nonvalvular atrial fibrillation. SPORTIF II: a dose-guiding, tolerability, and safety study.

OBJECTIVES: We sought to compare the tolerability and safety of three fixed doses of ximelagatran versus warfarin in patients with nonvalvular atrial fibrillation (NVAF). BACKGROUND: Anticoagulants such as warfarin lower the risk of stroke in patients with NVAF. Ximelagatran is a novel, oral direct thrombin inhibitor with predictable pharmacokinetics and no known food or pharmacokinetic drug interactions. METHODS: This was a 12-week, randomized, parallel-group, dose-guiding study of NVAF patients with at least one additional risk factor for stroke. The primary end point was the number of thromboembolic events and bleedings. Three groups received ximelagatran (n = 187) at 20, 40, or 60 mg twice daily, given in a double-blind fashion, without routine coagulation monitoring. In a fourth group, warfarin (n = 67) was managed and monitored according to normal routines, aiming for an International Normalized Ratio of 2.0 to 3.0. RESULTS: A total of 254 patients received study drug. One ischemic stroke (nonfatal) and one transient ischemic attack (TIA) occurred in the ximelagatran group. Two TIAs occurred in the warfarin group. No major bleeds were observed in the ximelagatran group. One major bleed occurred in a warfarin-treated patient. The number of minor and multiple minor bleeds was low, but there was a slight increase by ximelagatran dose. The 60-mg dose resulted in the same number of bleeding events as that with warfarin. S-alanine aminotransferase was increased in eight patients (4.3%) taking ximelagatran, but normalized with continuous treatment or cessation of the drug. CONCLUSIONS: Fixed oral doses of ximelagatran up to 60 mg twice daily were well tolerated, without the need for dose adjustment or coagulation monitoring.