BackgroundObservational studies have shown reduced perioperative bleeding in patients undergoing minimally invasive, compared with full sternotomy, aortic valve replacement. Data from randomized trials are conflicting.MethodsThis was a Swedish single center study where adult patients with aortic stenosis, 100 patients were randomly assigned in a 1:1 ratio to undergo either minimally invasive (ministernotomy) or full sternotomy aortic valve replacement. The primary outcome was severe or massive bleeding defined by the Universal Definition of Perioperative Bleeding in adult cardiac surgery (UDPB). Secondary outcomes included blood product transfusions, chest tube output, re-exploration for bleeding, and several other clinically relevant events.ResultsOut of 100 patients, three patients randomized to ministernotomy were intraoperatively converted to full sternotomy (none was bleeding-related). Three patients (6%) in the full sternotomy group and 3 patients (6%) in the ministernotomy group suffered severe or massive postoperative bleeding according to the UDPB definition (p = 1.00). Mean chest tube output during the first 12 postoperative hours was 350 (standard deviation (SD) 220) ml in the full sternotomy group and 270 (SD 190) ml in the ministernotomy group (p = 0.08). 28% of patients in the full sternotomy group and 36% of patients in the ministernotomy group received at least one packed red blood cells transfusion (p = 0.39). Two patients in each group (4%) underwent re-exploration for bleeding.ConclusionsMinimally invasive aortic valve replacement did not result in less bleeding-related outcomes compared to full sternotomy.Clinical Trial Registrationhttp://www.clinicaltrials.gov. Unique identifier: NCT02272621.