Activated clotting time differential is a superior method of monitoring anticoagulation following coronary angioplasty

Heparinase thromboelastography compared with activated coagulation time for protamine titration after cardiopulmonary bypass

OBJECTIVE

The present study is a comparison of two point-of-care (POC) tests as endpoints of protamine titration after CPB. The authors hypothesized that using the heparinase-kaolin thromboelastography (TEG-HK) R-time difference would more readily identify residual heparin necessitating additional protamine than when using activated coagulation time (ACT). The primary endpoint was the between-group difference in protamine dose. Whether this approach would lessen postoperative bleeding and sequelae also was investigated.

DESIGN

Single center, blinded, prospective, randomized study.

SETTING

University teaching hospital.

PARTICIPANTS

Eighty-two adult patients for on-pump coronary artery bypass and/or valve surgery.

INTERVENTIONS

Patients were randomized. In the ACT group, protamine was titrated until ACT did not exceed baseline by more than 10%. In the TEG group, a TEG-HK R-time difference less than 20% was targeted. Protamine was repeated to achieve the endpoints. Clinicians in the ACT group were blinded to TEG data and vice versa.

MEASUREMENTS AND MAIN RESULTS

There was no between-group difference in total protamine dose (3.9 ± 0.6 and 4.2 ± 0.7; 95% CI of the difference between means: -0.544 to 0.008 mg/kg; p = 0.057) or protamine:heparin ratios (1.3:1 and 1.4:1; 95% CI of the difference between means: -0.05 to 0.03 mg/mg; p = 0.653). In the ACT group, 17% of patients required a second protamine dose, and in the TEG group, 24% of patients required a second protamine dose. No between-group differences in the postoperative transfusion requirements or intensive care unit length of stay were demonstrated.

CONCLUSION

No difference was identified in protamine dosing using either ACT or TEG-HK R-time difference as endpoints. Heparinase TEG may be useful for monitoring heparin reversal.

Heparin dosing in patients undergoing coronary intervention

Unfractionated heparin remains an essential component of the antithrombotic regimen in patients undergoing coronary intervention, although the timing, dosing, and duration of heparin therapy have evolved over the past several years. Complications associated with heparin use include bleeding events, which occur in 3.9-16.4% of patients receiving conventional heparin. Less commonly, clinically significant thrombocytopenia develops, related to the duration of heparin administration. In patients undergoing coronary intervention who do not receive platelet glycoprotein (GP) IIb/IIIa inhibitors, sufficient heparin should be given to achieve an activated clotting time (ACT) of 250-300 seconds with the HemoTec device and 300-350 seconds with the Hemochron device. There is a general trend to use lower, weight-adjusted heparin dosing (70-100 units/kg) to avoid excessive levels of anticoagulation, with additional heparin boluses to achieve a therapeutic ACT level. When GP IIb/IIIa inhibitors are used, weight-adjusted heparin dosing can be decreased to 70 units/kg to achieve a target ACT of 200 seconds with either the HemoTec or Hemochron device. After uncomplicated coronary intervention, there appears to be little value associated with continued heparin therapy, and the risk of bleeding complications clearly increases with longer durations and higher levels of anticoagulation after coronary intervention.

Abrupt vessel closure: changing importance, management, and consequences

Percutaneous coronary interventions have been performed for 20 years. Despite the success and progress of these interventions, abrupt vessel closure has been a dramatic adverse event of coronary interventions. Closure has frequently led to the major complications of death, myocardial infarction, and emergency coronary artery bypass. Because of the fear of this adverse event and its subsequent complications, the applicability of coronary interventions is sometimes limited. The pathologic characteristics of abrupt vessel closure have been recognized as predominantly caused by dissection, with vessel recoil and thrombus formation playing important secondary roles. The recognition of the lesions at risk for abrupt vessel closure has led to a strategy of lesion-specific device therapy to reduce complications. Similarly the role of antiplatelet and antithrombotic therapies have reduced complications. The earliest methods of dealing with abrupt closure was emergency coronary artery bypass surgery with significant rates of morbidity and mortality. With the advent of second-generation devices and techniques, particularly stents, the management of abrupt vessel closure has been simplified and alternatives to emergency coronary bypass are more available. This article will review the history and current status of the prevention and management of abrupt vessel closure and demonstrate that anticipation and management of this complication have been facilitated with reduction of subsequent complications and increased applicability of coronary interventions.

When we "act" on ACT levels: activated clotting time measurements to guide heparin administration during and after interventional procedures

The establishment and monitoring of anticoagulation before, during, and after interventional and invasive procedures are crucial responsibilities. However, few prospective studies exist to rationally guide us in how and when to "act" in response to ACT values in specific clinical situations. Definitive studies to reach a uniform and safe ++approach are needed. The articles published in this issue of Catheterization and Cardiovascular Diagnosis represent an important step in understanding the role and value of ACT levels.