Excess bleeding and stroke rates in people with raised RVSP taking dabigatran could be explained by greater temporal fluctuations in dabigatran levels with increased caval pressures due to very high renal excretion (80%) relative to apixaban (25%) and rivaroxaban (36%), in addition to more variable expression of itssactivating enzyme, carboxylesterase 1, in pulmonary hypertension [51–53]. This evidence concerns the gene CES1 and pulmonary arterial hypertension.