SummaryObjective: Minimal extracorporeal circulation (MECC) is a new perfusion technology, which includes a centrifugal pump and an optoelectrical suction system. The main advantage consists in a significant reduction of the priming volume. Aim of the present study was to analyse if MECC has a positive effect in term of reduction of the activation of inflammatory markers and on the incidence of postoperative atrial fibrillation (AF) in comparison to conventional cardiopulmonary bypass (CPB). Methods: Two collectives have been studied: 30 patients scheduled for isolated coronary artery bypass graft (CABG) surgery were randomised to either receive MECC or CPB. Activation of inflammatory markers (IL-6, SC5-b9, Human Lactoferrin) was analysed. In a second collective 86 patients were analysed to evaluate the incidence of AF: 41 patients (47.7%) with CPB and 45 patients (52.3%) with MECC. Patients' characteristics were similar in both groups. In-hospital outcome was assessed. Results: Inflammatory markers were significant lower in the MECC-group early post operative. AF was documented in 16 patients (39.0%) of the CPB and in 5 patients (11.1%) of the MECC group (p <0.05). Postoperative the increase of weight was less pronounced in the MECC group (2.9 ± 2.4% vs 4.4 ± 2.6%; p <0.05). Antiarrhythmic medication was similar in both groups and administered in 95.1% of the patients in the CPB and in 93.3% in the MECC group (p = ns). No differences were found in serum potassium between the two groups (p = ns). Conclusion: MECC is an established and safe perfusion technique. Activation of inflammatory markers is less pronounced in MECC than in CPB patients. The reduction of the priming volume leads to a less pronounced volume shift in the early postoperative period and reduces the incidence of postoperative AF, compared to patients operated with CPB. Resultate: Die Entzündungsmarker waren früh postoperativ in der MECC-Gruppe signifikant tiefer. VHF konnte bei 16 Patienten (39,0%) aus der HLM-und bei 5 Patienten (11,1%) aus der MECC-Gruppe (p <0,05) dokumentiert werden. Postoperativ war der Gewichtsanstieg weniger ausgeprägt in der MECCGruppe (2,9 ± 2,4% vs 4,4 ± 2,6%; p <0,05). Die antiarrhythmische Medikation mit Betablocker war in beiden Gruppen mit einem Anteil von 95,1% in der HLM-und 93,3% in der MECC-Gruppe identisch (p = ns). Die Serumkalium-Werte waren ebenfalls in beiden Gruppen identisch (p = ns).