Ivan Burcar

NT-pro-BNP, but not C-reactive protein, is predictive of atrial fibrillation in patients undergoing coronary artery bypass surgery

OBJECTIVE Atrial fibrillation (AF) remains the most commonly observed complication following myocardial revascularisation surgery. We aimed to evaluate the clinical utility of N-terminal fragment of the brain natriuretic peptide (NT-pro-BNP), troponin T, transcoronary lactate gradient (TCLG) and C-reactive protein (CRP) as predictors of AF in patients undergoing isolated coronary artery bypass surgery (CABG). METHODS This study included 215 consecutive patients in sinus rhythm (SR) undergoing elective CABG between May 2007 and May 2008. The patients were grouped according to their respective postoperative rhythm into SR and AF groups. The data are presented as mean values+/-standard deviation, or medians with quartiles. RESULTS Fifty-five patients developed AF (26%). The preoperative NT-pro-BNP values were 273+/-347 and 469+/-629 pg ml(-1) in the SR and AF groups, respectively (p<0.0001). The postoperative NT-pro-BNP values were 3110+/-3600 pg ml(-1) in the SR and 4625+/-5640 pg ml(-1) in the AF groups (p=0.027). The transcoronary lactate gradient rose from the pre-cardiopulmonary bypass values to those observed 5 min after revascularisation in both groups (-0.05+/-0.37 to 0.39+/-0.46 mmol l(-1) (p<0.0001) in the SR group and -0.01+/-0.27 to 0.43+/-0.46 mmol l(-1) (p<0.0001) in the AF group). The CRP values increased from 6+/-13 to 163+/-88 mg l(-1) (p<0.0001) in the SR group, and from 6+/-16 to 163+/-104 mg l(-1) (p<0.0001) in the AF group. The dynamics of TCLG and CRP did not differ between the groups (p=0.71, p=0.44, respectively). The troponin T values on postoperative day 1 were significantly higher in the AF than the SR group (0.86 (0.49-2.1) ng ml(-1) vs 0.67 (0.37-1.16) ng ml(-1), p=0.046). The duration of cardiopulmonary bypass (CPB) was 85+/-24 min in the SR and 93+/-30 min in the AF group (p=0.05). Patients who developed AF were older (66+/-7 years vs 60+/-9 years, p<0.0001) and had a higher EuroSCORE (3.9+/-2.7 vs 2.9+/-2.2, p=0.009). Multivariate analysis identified age (p=0.0043), preoperative NT-pro-BNP (p=0.019) and duration of CPB (p=0.035) as independent predictors of AF. CONCLUSIONS Preoperative and postoperative NT-pro-BNP as well as TnT values were significantly higher in patients who subsequently developed AF. TCLG and CRP were not useful in identifying patients at higher risk for AF. Multivariate analysis identified age, preoperative NT-pro-BNP and duration of CPB as independent correlates of AF.

Preoperative aspirin use and outcomes in cardiac surgery patients: a role of platelet function assessment.

To the Editor: W e read with great interest the recently published study by Cao et al.1 Patients were divided into 2 groups: those taking (n = 1923) or not taking (n = 945) aspirin within 5 days preceding surgery.1 The authors compared 2 groups according to outcomes such as 30-day all-cause mortality, postoperative renal failure/dialysis required, and a composite outcome—major adverse cardiocerebral events (MACE); the latter included permanent or transient stroke, coma, perioperative myocardial infarction, heart block, and cardiac arrest.1 Other outcomes were readmission and intensive care unit stay. The authors showed that preoperative aspirin therapy (vs nonaspirin) significantly reduced the risk of 30-day mortality (P = 0.031), postoperative renal failure (P < 0.001), dialysis required (P < 0.001), intensive care unit stay (P < 0.001), and a composite MACE outcome (P = 0.011).1 In our opinion, the lack of objective quantification of the antiplatelet effect of aspirin in the group of patients taking aspirin within 5 days preceding surgery constitutes a major drawback of the study. Expected inhibition of platelet function is not always achieved after aspirin administration. Literature reports already described a wide variability in platelet response to aspirin therapy, with prevalence of aspirin resistance, as defined by platelet function tests, ranging from 1% to 45%.2 Residual platelet reactivity, the so-called, aspirin resistance, after aspirin administration might be related to thrombotic complications and major ischemic events, both preand postoperatively despite aspirin administration.3 As Cao et al1 described, most patients underwent coronary arteries revascularization (n = 1916; 66.8%), either in the form of isolated coronary artery bypass grafting (CABG) (n = 1474; 51.4%) or valve plus CABG (n = 442; 15.4%).1 Aortocoronary vein graft disease comprises 3 distinct but interrelated pathological processes: thrombosis, intimal hyperplasia, and atherosclerosis. Early thrombosis is a major cause of vein graft attrition during the first month after surgical procedure4 and inevitably influences the composite MACE outcome in the study by

How to prevent bleeding events in on- and off-pump coronary artery bypass patients exposed to clopidogrel preoperatively

The effect of clopidogrel on bleeding mainly depends on two factors: (1) observed platelet inhibition, which is depending on inherent platelet activity prior to clopidogrel administration and platelet inhibitory response to clopidogrel and (2) newborn platelets ability to restore normal aggregation after clopidogrel discontinuation.The role of aspirin and clopidogrel on bleeding should separately be assessed by drug specific platelet function tests, facilitating individual therapeutic approach for each antiplatelet agent preoperatively. Such an approach could distinguish patients with high residual platelet activity, thus proclivity to ischemic events, or enhanced platelet inhibition, thus proclivity to excessive bleeding. It would be interesting if authors compared preoperative ischemic events incidence between patients groups with respect to preoperative clopidogrel treatment. Timing of discontinuation as well as intensity of preoperatively administered aspirin and clopidogrel should be tailored according to drug specific platelet function tests in order to minimize both ischemic and bleeding events. In group of patients with pronounced platelet inhibition after aspirin and/or clopidogrel administration, early antiplatelet drug discontinuation should be considered. For elective patients, delaying of surgery in cases of pronounced platelet inhibition after antiplatelet drugs administration should be considered if clinically condition allows. For urgent and/or emergent cases with observed preoperative deep platelet inhibition, the desmopressin administration should be considered [5] as well as intraoperative thromboelastography guided hemostatic therapy which significantly reduces incidence of overall transfusion and mediastinal re-exploration due to excessive bleeding [6]. However, such an approach requires further studies in order to provide platelet function test cut-off values that delineate bleeding as well as ischemic events. According to obtained cut-off values, antiplatelet therapy management should be evaluated in context of clinical outcome.

Haemostatic management in high-risk cardiac surgery : a role of recombinant factor VIIa (NovoSeven RT)

We read with great interest the recently published retrospective study by Chapman et al .[ 1]. The authors matched 236 patients with recombinant factor VIIa (rFVIIa) administration with a control group of 213 patients without rFVIIa treatment. The majority of procedures involved coronary artery bypass graft surgery: 51.7% in the rFVIIa group and 53.5% in the control group. We are interested whether those patients were preoperatively exposed to anti-thrombotic therapy with acetylsalicylic acid and/or clopidogrel. If so, was the proportion of patients with either mono or dual preoperative anti-thrombotic therapy different among the groups? Did the authors perform a platelet function test prior to the procedure in order to determine the platelet function? The acquired platelet function disorder plays a major role in perioperative bleeding in cardiac surgery. Therefore, the use of point-of-care suitable platelet function analysers seems to be reasonable in this field. The rFVIIa group had a significantly higher rate of re-operation for bleeding, a two fold increase in the use of blood products and, more frequently, had pulmonary complications. In addition, Hacquard et al .[ 2] have reported 20% of patients with rFVIIa administration who continued to bleed severely despite rFVIIa therapy. The rFVIIa group received rFVIIa after bleeding had not responded to traditional therapy, and some of the patients received one or two additional doses. It remains unclear whether the traditional blood component administration was targeted after intraoperative thromboelastography haemostatic property assessment. Spiess et al. have reported thromboelastography-guided haemostatic management to significantly reduce the incidence of the overall transfusion and mediastinal re-exploration due to excessive bleeding [3]. Targeted therapy enables more efficient haemostatic treatment, based on functional deficiency, thus leading to lower dosages of blood component therapy. Furthermore, thromboelastography-guided haemostatic therapy with the reduced and targeted procoagulant blood component administration can reduce respiratory complications. Optimization of haemostatic properties, guided by thromboelastography, can lead to diminished use of rFVIIa and, if rFVIIa is deemed necessary, its efficiency could be better after functional haemostatic property optimization. We believe that intraoperative haemostatic property optimization guided by viscoelastic tests of whole-blood coagulation and platelet function should precede rFVIIa administration. Such an approach can improve the rFVIIa efficiency and therefore diminish the 11% prevalence of patients requiring re-exploration despite rFVIIa administration. In our experience, algorithms for perioperative coagulation management based on the point-of-care testing permit a fast diagnostic and goaldirected therapy of coagulation and functional platelet disorders with only sporadic need for rFVIIa administration. We congratulate the authors on their elegant and timely research.