Aspirin resistance as cardiovascular risk after kidney transplantation

International surveys have shown that the leading cause of death after kidney transplantation has cardiovascular origin with a prevalence of 35–40%. As a preventive strategy these patients receive aspirin (ASA) therapy, even though their rate of aspirin resistance is still unknown. In our study, platelet aggregation measurements were performed between 2009 and 2012 investigating the laboratory effect of low-dose aspirin (100 mg) treatment using a CARAT TX4 optical aggregometer. ASA therapy was considered clinically effective in case of low (i.e., below 40%) epinephrine-induced (10 μM) platelet aggregation index. Rate of aspirin resistance, morbidity and mortality data of kidney transplanted patients (n = 255, mean age: 49 ± 12 years) were compared to a patient population with cardio- and cerebrovascular diseases (n = 346, mean age: 52.6 ± 11 years). Rate of aspirin resistance was significantly higher in the renal transplantation group (RT) compared to the positive control group (PC) (35.9% vs. 25.6%, p < 0.002). Morbidity analysis demonstrated significantly higher incidence of myocardial infarction, hypertension and diabetes mellitus in the RT group (p < 0.05). The subgroup analysis revealed significantly higher incidence of infarction and stroke in the ASA resistant RT group compared to the RT patients without ASA resistance (p < 0.05). Furthermore, the incidence of myocardial infarction and hypertension was significantly higher in the non-resistant RT group than in the group of PC patients without ASA resistance (p < 0.05). These results may suggest that the elevated rate of aspirin resistance contributes to the high cardiovascular mortality after kidney transplantation.