Effect of preoperative P2Y12 and thrombin platelet receptor inhibition on bleeding after cardiac surgery

BACKGROUND: Drugs that act on the platelet P2Y12 receptor are responsible for postoperative bleeding in cardiac surgery. However, protease-activated receptor (PAR) that reacts to thrombin stimulation might still be active in patients treated with P2Y12 inhibitors. Preoperative platelet function testing could possibly guide the timing of surgery. We investigated the association between P2Y12 receptor and PAR inhibition and bleeding after cardiac surgery. METHODS: A retrospective cohort study of 361 patients undergoing cardiac surgery and treated with P2Y12 anti-platelet agents was undertaken. All patients received a preoperative multiplate electrode aggregometry testing of platelet P2Y12 receptor activity (ADPtest) and PAR reactivity with thrombin receptor-activating peptide (TRAP) stimulation. ADPtest and TRAPtest data measured before surgery were analysed for association with postoperative bleeding (ml per 12 h) and severe postoperative bleeding. RESULTS: Both the ADPtest and the TRAPtest were significantly (P=0.001) associated with postoperative bleeding. A threshold of 22 U for the ADPtest yielded a negative predictive value (NPV) of 94% and a positive predictive value (PPV) of 20%, and a threshold of 75 U for the TRAPtest yielded an NPV of 95% and a PPV of 23%. In the subgroup of patients with ADPtest <22 U, TRAPtest ≥75 U was not associated with severe bleeding (NPV of 100% and PPV of 37%). CONCLUSIONS: In patients taking P2Y12 receptor inhibitors, residual platelet reactivity to thrombin stimulation limits the risk of severe postoperative bleeding

The combined effects of the microcirculatory status and cardiopulmonary bypass on platelet count and function during cardiac surgery

ACKGROUND: Cardiac surgery with cardiopulmonary bypass is associated with important changes in the microcirculation, usually attributed to endothelial dysfunction. Another common finding of cardiac surgery is postoperative thrombocytopenia and platelet loss of function. OBJECTIVE: To investigate the association between microvascular flow pattern and postoperative changes in platelet count and function in cardiac surgery patients. METHODS: Twelve adult cardiac surgery patients received microvascular circulation (sidestream darkfield sublingual mucosa analysis) and platelet count and function (multiple electrode aggregometry ADPtest and TRAPtest) assessment before and after cardiopulmonary bypass. RESULTS: After cardiopulmonary bypass, sublingual microcirculation showed a significantly (P = 0.001) decreased microvascular flow index and increased heterogeneity index (P = 0.006). Platelet function significantly decrease after cardiopulmonary bypass both at ADPtest (P = 0.011) and TRAPtest (P = 0.002). Preoperative patterns of poor microvascular perfusion (low perfused vessels density and total vessels density) were significantly associated with lower values of post-cardiopulmonary bypass platelet function (ADPtest, P = 0.009, TRAPtest, P = 0.031) and count (P = 0.048). CONCLUSIONS: A preoperative disturbance of the microcirculation is associated with a greater postoperative platelet dysfunction. Endothelial damage, chemical and mechanical stimuli are the possible link between the two patterns

Impact of preoperative anemia on outcome in adult cardiac surgery: a propensity-matched analysis.

Preoperative anemia is not considered an operative mortality risk factor by the majority of the risk stratification tools used in cardiac surgery. However, retrospective studies have found associations between preoperative anemia and morbidity and mortality in cardiac operations. The present study compares the postoperative outcome of a group of moderate-to-severe anemic patients with a propensity-matched group of nonanemic patients undergoing cardiac operations. METHODS: This is a retrospective study based on 17,056 consecutive patients included in our Institutional Database. A total of 13,843 adult patients with preoperative hematocrit value available were selected for this study; 401 patients had a severe anemia (hematocrit<30%). From the remaining patients, a control group of 401 non-severely anemic patients was selected with a propensity-based matching. Postoperative morbidity and mortality were compared between the 2 groups. RESULTS: The 2 groups were comparable for preoperative comorbidities and operative details. Anemic patients had a significantly (p=0.045) higher rate of stroke (1% vs 0%), major morbidity (27.4% vs 17.5%, p=0.001), and a significantly higher (0.014) operative mortality rate (12.7% vs 7.5%). An additional analysis, inclusive of patients with moderate preoperative anemia, confirmed these results. CONCLUSIONS: Moderate-to-severe preoperative anemia is a risk factor for major morbidity and operative mortality in adult cardiac operations. This finding is confirmative of the role of preoperative anemia in determining adverse events in major noncardiac operations. The exclusion of preoperative anemia from the existing risk scores is probably a statistical consequence of the associated comorbid conditions that confound the specific role of anemia as a risk factor

Accuracy, calibration and clinical performance of the new EuroSCORE II risk stratification system.

OBJECTIVES: The European System for Cardiac Operative Risk Evaluation (EuroSCORE) has been used for many years since its introduction in 1999. Recently, a new EuroSCORE (EuroSCORE II) has been developed to update the previous version. The EuroSCORE II includes some different predictors and/or introduces a new classification of the already existing predictors. This study presents a validation series for the EuroSCORE II compared with the previous additive and the logistic EuroSCORE and with the Age, Creatinine and Ejection Fraction (ACEF) score. METHODS: A total of 1090 consecutive adult patients operated on at our institution from September 2010 to October 2011 were admitted to this retrospective study. All the patients received a risk stratification based on the EuroSCORE II and the other scores considered. Accuracy, calibration and clinical performance of the various risk models were assessed. RESULTS: The accuracy of the EuroSCORE II was good (c-statistic 0.81) but not significantly higher than the other scores (range 0.78-0.8). Calibration at the Hosmer-Lemeshow statistic was good for all the scores; the difference between observed (3.75%) and predicted mortality in the overall population was not significant for the EuroSCORE II (3.1%) and the ACEF score (3.4%), whereas the additive EuroSCORE (5.8%) and the logistic EuroSCORE (7.3%) significantly overestimated the risk. In patients at low, mild moderate and high mortality risk, the EuroSCORE II provided a risk prediction not significantly different from the observed mortality rate, whereas in very high-risk patients (observed mortality rate 11%), it significantly underestimated (6.5%) the mortality risk. The accuracy of the EuroSCORE II was acceptable in isolated coronary surgery, and good or excellent in the other operations. CONCLUSIONS: The EuroSCORE II represents a useful update of the previous EuroSCORE version, with a much better clinical performance and the same good level of accuracy. It is possible that for the risk stratification of very high-risk patients, other factors (rare but associated with a mortality rate >50%) should be included in the future models