 During the follow-up period or double-blind treatment period between a minimum of 3 and 6.5 years depending on the length of the recruitment, subjects will receive study medications as fixed doses. During the follow-up period, subjects will visit the clinic every 6 months up to a maximum of 78 months. Subjects will take either rivaroxaban 15 mg with matching acetylsalicylic acid - placebo or acetylsalicylic acid 100 mg with matching rivaroxaban-placebo orally, once daily, preferably at the same time of the day throughout the study. 