The origin of both and the role in AF progression remains unknown, but the postulated enhanced potential of tissue factor stimulated coagulation, due to lower TFPI activity, by itself would be in accordance with a role of hypercoagulability in driving AF as previously shown in preclinical studies.9 Recently, it was shown that duration of PAF was associated with higher levels of von Willebrand factor and factor VIII.26 Clearly, more research is warranted on the role of hypercoagulability in AF progression. The gene discussed is TFPI; the disease is thrombophilia.