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Aortic stenosis is the most common valvular disease worldwide. Coronary artery disease (CAD) is often associated with degenerative aortic stenosis, particularly among older patients. Surgical treatment of the combined pathologies is highly recommended because the results are durable. Assessment of mitochondrial respiration in blood cells has recently emerged as a potential biomarker of the bioenergetic health but data regarding the changes in the setting of cardiopulmonary bypass (CPB) are scarce. A 67-year-old man was referred to the clinic for progressive breathlessness, constrictive thoracic pain and fatigue. Investigations revealed severe aortic stenosis and triple-vessel CAD. The aortic valve was replaced with a mechanical aortic prosthesis and coronary artery bypass graft was performed under mild hypothermia. We assessed platelet complex I (CI)- and complex II (CII)-dependent mitochondrial respiration and found a significant increase in the net active respiration supported by CI and the maximal uncoupled respiration in platelets harvested after CPB compared to those isolated pre-CPB. At variance, the active coupled respiration and electron transfer capacity for CII were decreased. The relative contribution of the complex cardiac pathology and CPB to the impairment of CII-dependent respiration and/or a possible relation with patients’ outcome are worth further investigation in a pilot study.

Keywords: aortic stenosis; bicuspid aortic valve; aortic valve replacement; coronary artery bypass grafting; cardiopulmonary bypass; platelet mitochondrial respiration