Prophylactic bosentan does not improve exercise capacity or lower pulmonary artery systolic pressure at high altitude.

Hypoxic pulmonary vasoconstriction in response to high altitude ascent may contribute to decreased exercise capacity. Endothelin receptor antagonists reduce pulmonary artery pressure and improve exercise capacity in patients with pulmonary arterial hypertension, but their effects on exercise capacity at altitude are unknown. We studied the efficacy of bosentan started 5 days prior to ascent on exercise capacity and pulmonary artery systolic pressure (PASP) at 3800 m altitude. Eight healthy subjects completed a double-blinded, randomized, placebo-controlled, crossover study. The end-points were time to complete a cycle ergometer time trial, PASP, and hemoglobin oxygen saturation (SpO2). The time to complete the time trial at altitude in subjects on placebo and bosentan was 527+/-159 and 525+/-156 s respectively (P=0.90). PASP was not different on bosentan compared with placebo. Mean SpO2 during the altitude time trial was lower in subjects taking bosentan compared to placebo (78+/-6 vs. 85+/-8% respectively, P=0.03). Bosentan initiated 5 days prior to ascent to high altitude did not improve exercise capacity or reduce PASP, and worsened SpO2 during high intensity exercise at altitude.

Clinical outcomes of prolonged anticoagulation with rivaroxaban after unprovoked venous thromboembolism.

BACKGROUND: Randomized trial data demonstrate the gain of extended duration anticoagulation in patients with venous thromboembolic events (VTE); however, real-world data are limited. OBJECTIVES: Assess the risk of recurrent VTE and major bleeding in a real-world setting of patients who experienced unprovoked VTE and received extended treatment with rivaroxaban. METHODS: US claims databases (February 2011-April 2015) were used in this retrospective study. The study population included adult patients initiated on rivaroxaban within 7 days after their first unprovoked VTE (ie, deep vein thrombosis, pulmonary embolism) and received ≥3 months continuous rivaroxaban treatment (index date: end of 3-month treatment). Patients who were treated beyond 3 months formed the continued cohort and the remainder formed the discontinued cohort (ie, discontinued at 3 months). Adjusted Kaplan-Meier rates for recurrent VTE and major bleeding events were compared between cohorts with confounders being controlled through a propensity score weighting approach. RESULTS: Patients in the continued cohort (N = 3763) had significantly lower rates of recurrent VTE than those who discontinued (N = 1051): 0.57% vs 1.19% (P = .042), 1.07% vs 2.10% (P = .017), and 1.45% vs 2.60% (P = .023) at 3, 6, and 12 months, respectively. No significant differences in the rate of major bleeding were observed between cohorts. A sensitivity analysis among unprovoked VTE patients receiving rivaroxaban for ≥6 months showed similar results. CONCLUSIONS: Continued rivaroxaban treatment beyond an initial 3- or 6-month treatment period significantly lowered the risk of recurrent VTE without a significant increase of major bleeding, compared to treatment discontinued at 3 or 6 months.

Risk for Venous Thromboembolism Recurrence Among Rivaroxaban-treated Patients Who Continued Versus Discontinued Therapy: Analyses Among Patients with VTE.

PURPOSE: The EINSTEIN-Extension trial showed that an extended rivaroxaban treatment significantly reduced the risk for venous thromboembolic (VTE) recurrence. The present study assessed the risk for VTE recurrence and major bleeding associated with extended rivaroxaban treatment in a clinical practice setting among patients with VTE. METHODS: A retrospective study was conducted using claims data from February 2011 to April 2015. It included adult patients who initiated rivaroxaban therapy within 7 days after their first VTE and who continuously used rivaroxaban for at least 3 months (index date: end of initial 3-month treatment). Categorized into discontinued and continued cohorts, patients were followed up from the index date until the end of continuous treatment (continued cohort) or end of data or reinitiation of oral anticoagulant therapy (discontinued cohort). Using inverse probability of treatment weights controlling for confounders, adjusted Kaplan-Meier rates of recurrent VTE and major bleeding events were compared. FINDINGS: The analysis showed that, compared with the discontinued cohort (n = 1,536), the continued cohort (n = 5,933) had a significantly lower VTE recurrence rate after an additional 3 months (0.70% vs 1.70%), 6 months (1.41% vs 2.34%), 9 months (1.82% vs 3.01%), and 12 months (1.97% vs 3.01%) of treatment (all, p < 0.05). The difference in the cumulative event rates for major bleeding was not statistically significant. Similar results were obtained in an analysis among patients with VTE receiving rivaroxaban for ≥6 months. IMPLICATIONS: Our results suggest that, in clinical practice settings, patients with VTE who continued rivaroxaban therapy after the initial 3- or 6-month treatment period had a significantly lower risk for VTE recurrence without a statistically significant increased risk for major bleeding.