Optimal intraoperative anticoagulation strategy in patients undergoing off-pump coronary artery bypass

The association between heparin sensitivity index and postoperative blood loss in Chinese patients undergoing elective off-pump coronary artery bypass grafting: a single center retrospective study

BACKGROUND

The heparin sensitivity index (HSI) is closely associated with perioperative ischemic events and increased blood loss in cardiac surgery. Previous studies have produced conflicting results. Therefore, this study aimed to investigate the relationship between HSI and postoperative blood loss specifically in Chinese patients undergoing elective off-pump coronary artery bypass grafting (OPCAB).

METHODS

Patients underwent OPCAB between March 2021 and July 2022 were retrospectively included. Enrolled patients were classified into Low-HSI (HSILOW; HSI < 1.3) and Normal-HSI (HSINORM; HSI ≥ 1.3) groups. HSI = [(activated clotting time (ACT) after heparin) - (baseline ACT)] / [loading dose of heparin (IU/kg)]. Primary outcome included postoperative blood loss at 24 h. Secondary outcomes were total postoperative blood loss, transfusion requirement of red blood cell (RBC), fresh frozen plasma (FFP), platelet concentrates (PC), and other complications.

RESULTS

We retrospectively analyzed 303 Chinese OPCAB patients. HSILOW group had higher preoperative platelet (PLT) count (221 × 109/L vs. 202 × 109/L; P = 0.041) and platelet crit (PCT) value (0.23% vs. 0.22%; P = 0.040) compared to HSINORM group. Two groups showed no significant differences in postoperative blood loss at 24 h (460 mL vs. 470 mL; P = 0.252), total blood loss (920 mL vs. 980 mL; P = 0.063), RBC transfusion requirement (3.4% vs. 3.1%; P = 1.000), FFP transfusion requirement (3.4% vs. 6.2%; P = 0.380), and other complications. Preoperative high PLT count was associated with low intraoperative HSI value (odds ratio: 1.006; 95% confidence interval: 1.002, 1.011; P = 0.008).

CONCLUSIONS

Intraoperative HSI value was not associated with postoperative blood loss in Chinese patients undergoing OPCAB. Preoperative high PLT count was an independent predictor of low intraoperative HSI value.

Optimum heparin dose in off-pump coronary artery bypass grafting: A systematic review and meta-analysis

INTRODUCTION

Off-pump coronary artery bypass grafting (OPCABG) was introduced many years ago aiming to reduce the known complications of conventional on-pump coronary surgeries. Heparin is required during the procedures, but the available protocols have diverse dosage regimens. The primary objective of this systematic review is to examine the effect of different heparin doses on the outcomes of OPCABG.

EVIDENCE ACQUISITION

MEDLINE and EMBASE were searched. Four reviewers identified eligible clinical trials. Two reviewers extracted data and independently assessed the risk of bias using Cochrane tool. The primary outcome was the activated clotting time (ACT) at three minutes. The secondary outcomes were proportion of patients requiring blood products and the length of hospital stay. An aggregate data approach was used.

EVIDENCE SYNTHESIS

Three single-center randomized studies recruiting 256 patients were included. The studies compared low-dose (1.5-2 mg/kg) and high-dose (3 mg/kg) heparin boluses. The overall mean difference for ACT after three minutes between low- and high-dose heparin is - 126.16 (95% CI: - 142.19, - 110.14). The proportion of patients requiring blood products after surgery [odd ratio 1.27 (95% CI: 0.69, 2.32)] or the overall length of stay [mean difference -0.15 (95% CI: -0.84, 0.53)] did not differ between the heparin doses.

CONCLUSIONS

In OPCABG, high-dose compared with low-dose heparin did not affect the utilization of more blood products or increased the overall length of stay. Unsurprisingly, ACT values were higher in the high-dose heparin group. Larger and adequately powered randomized clinical trials are indicated to resolve the uncertainty.

Clinical outcomes associated with type II myocardial infarction caused by bleeding

BACKGROUND

Type ll myocardial infarction (T2MI) is caused by a mismatch between myocardial oxygen supply and demand. One subset of individuals is T2MI caused by acute hemorrhage. Traditional MI treatments including antiplatelets, anticoagulants, and revascularization can worsen bleeding. We aim to report outcomes of T2MI patients due to bleeding, stratified by treatment approach.

METHODS

The MGB Research Patient Data Registry followed by manual physician adjudication was used to identify individuals with T2MI caused by bleeding between 2009 and 2022. We defined 3 treatment groups: (1) invasively managed, (2) pharmacologic, and (3) conservatively managed Clinical parameters and outcomes for 30-day, mortality, rebleeding, and readmission were abstracted compared between the treatment groups.

RESULTS

We identified 5,712 individuals coded with acute bleeding, of which 1,017 were coded with T2MI during their admission. After manual physician adjudication, 73 individuals met the criteria for T2MI caused by bleeding. 18 patients were managed invasively, 39 received pharmacologic therapy alone, and 16 were managed conservatively. The invasively managed group experienced lower mortality (P = .021) yet higher readmission (P = .045) than the conservatively managed group. The pharmacologic group also experienced lower mortality (P= .017) yet higher readmission (P = .005) than the conservatively managed group.

CONCLUSION

Individuals with T2MI associated with acute hemorrhage are a high-risk population. Patients treated with standard procedures experienced higher readmission but lower mortality than conservatively managed patients. These results raise the possibility of testing ischemia-reduction approaches for such high-risk populations. Future clinical trials are required to validate treatment strategies for T2MI caused by bleeding.

Anesthesia management of patients undergoing off-pump coronary artery bypass grafting: A retrospective study of single center

Background

To summarize the current practice of anesthesia management for Chinese patients undergoing off-pump coronary artery bypass (OPCAB) surgery at a large-volume cardiovascular center.

Materials and methods

The clinical data of consecutive patients undergoing isolated, primary OPCAB surgery during the period from September 2019 to December 2019 were retrospectively analyzed. Patient characteristics, intraoperative data, and short-term outcomes were extracted from the Hospital Information System and the Anesthesia Information Management System.

Results

A total of 255 patients who underwent OPCAB surgery were enrolled in the current study. High-dose opioids and short-acting sedatives were the most commonly administrated anesthetics intraoperatively. Pulmonary arterial catheter insertion is frequently performed in patients with serious coronary heart disease. Goal-directed fluid therapy, a restricted transfusion strategy, and perioperative blood management were routinely used. Rational usages of inotropic and vasoactive agents facilitate hemodynamic stability during the coronary anastomosis procedure. Four patients underwent re-exploration for bleeding, but no death was observed.

Conclusions

The study introduced the current practice of anesthesia management at the large-volume cardiovascular center, and the short-term outcomes indicated the efficacy and safety of the practice in OPCAB surgery.

Challenges of antithrombotic therapy in the management of cardiovascular disease in patients with inherited bleeding disorders: A single-centre experience

INTRODUCTION

Cardiovascular events in patients with inherited bleeding disorders are challenging to manage. The risk of bleeding secondary to antithrombotic treatment must be balanced against the risk of thrombosis secondary to haemostatic therapy.

METHODS

Patients with inherited bleeding disorders with coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI) or atrial fibrillation (AF) from a single centre (2010-2018) are included.

RESULTS

A total of 11 patients undergoing CABG (n = 3), PCI (n = 5) or with AF (n = 3) and a diagnosis of haemophilia A (n = 8), haemophilia B (n = 1), factor XI deficiency (n = 1) and von Willebrand disease (n = 1) managed by a multidisciplinary team are reported. In patients undergoing CABG, factor levels were normalized for 7-10 days with trough levels of 70-80% with severe patients continuing high-dose factor prophylaxis (trough 20-30%) three weeks post-operatively with daily aspirin. In a patient with mild haemophilia A and an inhibitor, recombinant factor VIIa dosing was monitored with thromboelastometry. For PCI, a 3rd-generation drug-eluting stent with one month of dual antiplatelet therapy in addition to high-dose prophylaxis as needed was preferred. Patients with AF and severe haemophilia did not receive antithrombotic treatment, and a thrombin generation assay was used to guide heparin dosing in mild haemophilia.

CONCLUSION

Our experience demonstrates the importance of interdisciplinary communication to identify strategies that decrease the risk of bleeding and thrombosis. The use of extended, increased intensity prophylaxis facilitated antiplatelet therapy. Global assays may help balance the intensity of haemostatic and antithrombotic treatment.

Comparison of two doses of heparin on outcome in off-pump coronary artery bypass surgery patients: A prospective randomized control study

Introduction:

While off pump coronary artery bypass surgery is practiced with an intention to reduce the morbidity associated with cardiopulmonary bypass, the resultant ‘hypercoagulability’ needs to be addressed. Complications such as cavitary thrombus possibly due to the hyper coagulability after off pump coronary artery bypass surgery have been described. Many clinicians use higher doses of heparin - up to 5 mg/kg in order to thwart this fear. Overall, there appears to be no consensus on the dose of heparin in off pump coronary artery bypass surgeries.

Aim of the Study:

The aim of the study was understand the differences in outcome of such as transfusion requirement, myocardial ischemia, and morbidity when two different doses were used for systemic heparinization.

Methods:

Elective patients scheduled for off pump coronary artery bypass surgery were included. Ongoing anti platelet medication was not an exclusion criteria, however, anti platelet medications were ceased about a week prior to surgery when possible. Thoracic epidural anesthesia was administered as an adjunct in patients who qualified for it. By computer generated randomization chart, patients were chosen to receive either 2 or 3 mg/kg of intravenous unfractioned heparin to achieve systemic heparinization with activated clotting time targeted at >240 secs. Intraoperative blood loss, postoperative blood loss, myocardial ischemic episodes, requirement of intraaortic balloon counter pulsation and transfusion requirement were analyzed.

Results:

Sixty two patients participated in the study. There was one conversion to cardiopulmonary bypass. The groups had comparable ACT at baseline (138.8 vs. 146.64 seconds, P = 0.12); 3 mg/kg group had significantly higher values after heparin, as expected. But after reversal with protamine, ACT and need for additional protamine was similar among the groups. Intraoperative (685.56 ± 241.42 ml vs. 675.15 ± 251.86 ml, P = 0.82) and postoperative blood loss (1906.29 ± 611.87 ml vs 1793.65 ± 663.54 ml, p value 0.49) were similar among the groups [Table 4]. The incidence of ECG changes of ischemia, arrhythmias, conversion to CPB, or need for intra-aortic balloon counter pulsation were not different.

Conclusions:

Use of either 2 or 3 mg/kg heparin for systemic heparinization in patients undergoing OPCAB did not affect the outcome.

Off-pump coronary artery bypass grafting using continuous heparin infusion

Objectives

Levels of anticoagulation during off-pump coronary artery bypass grafting (OPCAB) remain controversial. Prolonged activated clotting time (ACT) during OPCAB increases blood loss during surgery and can also cause paradoxical increase in postoperative myocardial infarction. Shorter ACT can increase thrombotic complication. Maintaining a steady ACT level is challenging. We have used continuous heparin infusion after initial bolus during OPCAB to maintain a steady low target ACT. The objective of the present study was to assess the effectiveness and safety of heparin infusion in maintaining a steady target ACT level.

Methods

This was a prospective study of consecutive OPCAB patients. ACT was measured after initial bolus dose of heparin. Once ACT of more than 200 seconds was achieved, heparin infusion was started to maintain the required level of anticoagulation. CPK-MB was measured in operation room, 6 and 24 hours postoperatively to rule out ischemic complication.

Results

ACT could be maintained in target range with heparin infusion in 80.1% patients (161/201). Of the 40 patients with one or more ACT reading less than 200 seconds, 38 patients were managed by increasing the dose of heparin infusion and only 2 patients required additional bolus dose of heparin.

Conclusions

Heparin infusion maintains a steady target ACT level and avoids peaks and troughs associated with bolus doses. Lower level of anticoagulation using continuous heparin infusion does not increase ischemic complications. This is the first ever study of use of heparin infusion during OPCAB. We may conclude that heparin infusion is a safe anticoagulation strategy for OPCAB.

Robotic cardiac surgery: an anaesthetic challenge

Robotic cardiac surgery with the da Vinci robotic surgical system offers the benefits of a minimally invasive procedure, including a smaller incision and scar, reduced risk of infection, less pain and trauma, less bleeding and blood transfusion requirements, shorter hospital stay and decreased recovery time. Robotic cardiac surgery includes extracardiac and intracardiac procedures. Extracardiac procedures are often performed on a beating heart. Intracardiac procedures require the aid of peripheral cardiopulmonary bypass via a minithoracotomy. Robotic cardiac surgery, however, poses challenges to the anaesthetist, as the obligatory one-lung ventilation (OLV) and CO2 insufflation may reduce cardiac output and increase pulmonary vascular resistance, potentially resulting in hypoxaemia and haemodynamic compromise. In addition, surgery requires appropriate positioning of specialised cannulae such as an endopulmonary vent, endocoronary sinus catheter, and endoaortic clamp catheter under the guidance of transoesophageal echocardiography. Therefore, cardiac anaesthetists should have a working knowledge of these systems, OLV and haemodynamic support.

Optimal anticoagulation during off pump coronary artery bypass in patients recently exposed to clopidogrel

PURPOSE

The aim of this study was to find an optimal range of activated clotting time (ACT) during off-pump coronary artery bypass surgery (OPCAB) yielding ischemic protection without the risk of hemorrhagic complications in patients with recent exposure to dual antiplatelet therapy.

MATERIALS AND METHODS

Three hundred and five patients who received aspirin and clopidogrel within 7 days of isolated multi-vessel OPCAB were retrospectively studied. Combined hemorrhagic and ischemic outcome was defined as the occurrence of 1 of the following: significant perioperative bleeding (>30% of estimated blood volume), transfusion of packed red blood cell (pRBC) ≥ 2 U, or myocardial infarction (MI). This was compared in relation to the tertile distribution of the time-weighted average ACT-212-291 sec (first tertile), 292-334 sec (second tertile), 335-485 sec (third tertile).

RESULTS

The amount of perioperative blood loss was 937 ± 313 mL, 1014 ± 340 mL, and 1076 ± 383 mL, respectively (p=0.022). Significantly more patients in the third tertile developed MI (4%, 4%, and 12%, respectively, p=0.034). The incidence of significant perioperative blood loss and transfusion of pRBC ≥ 2 U were lower in the first tertile than those of other tertiles without statistical significance. In the multivariate analysis, the first tertile was associated with a 52% risk reduction of combined hemorrhagic and ischemic outcomes (95% confidence interval: 0.25-0.92, p= 0.027).

CONCLUSION

A lower degree of anticoagulation with a reduced initial heparin loading dose should be carefully considered for patients undergoing OPCAB who have recently been exposed to clopidogrel.