Background and aim of the study: Aim of this study is to compare the incidence of postoperative bleeding events, identified as pericardial effusion, for those patients undergoing cardiac surgery and discharged on vitamin K antagonist (VKA) versus those discharged on NOACs. Methods: This was a retrospective observational cohort study; from July 2017 to July 2019, all the patients who underwent any cardiac surgical procedure and discharged on any oral anticoagulant, were rolled in the study. The study variables and setting followed the STROBE checklist. The final cohort was constituted by 382 patients (mean age 70±11.2 years); 260(68.1%) patients were discharged on VKA and 122(31.9%) were discharged on NOACs. The primary end point was the incidence of major postoperative bleeding, defined as pericardial effusion requiring surgical re-exploration. The key secondary composite end point was the late re-admission for pericardial effusion. Results: The overall incidence of in-hospital immediate bleeding events, with need of re-exploration for pericardial effusion, was 4.7% (n=18). The incidence of re-admission for pericardial effusion was 3.1% (n=12). Eight of those patients had surgical re-exploration: four patients were discharged on NOACs and the remnant four ones were discharged on VKA. No significant relationships were observed between the different oral anticoagulants and the incidence of pericardial effusion, at any time. No ischemic and thromboembolic events were recorded. Conclusions: The use of non-vitamin K antagonist oral anticoagulant, in post cardiac surgery patients, does not increase the incidence of major bleeding events, intended as immediate or late pericardial effusion.