Statistical analysis: Endpoint assessment will be performed with a per protocol analysis, and demonstrated as Kaplan Meyer (KM) estimates of event free survival and event rates per year. The results will be compared with KM estimates and event rates from a historical similar cohort on VKA in a non-inferiority assay. Drop-outs (see below) will be censored at time of drop-out in time-to-event analyses, and included for event-rate analyses up to time of drop-out. No adjustment or imputation of missing data will be performed and all available data will be presented.