Baseline activated clotting time values could help to reduce bleeding after TAVI

82

Chiara Bernelli (Interventional Cardiology Unit, San Raffaele Scientific Institute, Milan, Italy) and others report in JACC: Cardiovascular Interventions that, in patients undergoing transfemoral trancatheter aortic valve implantation (TAVI), baseline activated clotting time (ACT)-guided heparin administration is associated with significantly less bleeding than heparin administration that is guided by the patient’s weight alone.

Bernelli et al report that TAVI-related bleeding remains an “important complication demanding careful consideration”. They add that excessive intraprocedural anticoagulation therapy with heparin may be a common cause of bleeding in this group but “no study has specifically evaluated appropriate heparin dosing in this clinical setting”. Therefore, the authors performed a retrospective review of consecutive patients who underwent transfemoral TAVI at their centre (San Raffaele Scientific Institute) between November 2007 and June 2012 to compare heparin administration based on the patient’s baseline ACT values (and weight) vs. a heparin administration based on the patient’s weight alone. The primary outcome was the rate of 30-day major bleeding, with secondary outcomes including life-threatening bleeding, minor bleeding, and any bleeding.


Of 326 patients in the study, 174 received ACT-guided heparin administration and 188 received non-ACT-guided heparin administration. Overall, baseline ACT values were 159.1±28.3s with 30.4% of patients having a baseline ACT of ≥175s.


Bernelli et al report: “Notably, in the ACT-guided group, a lower dose of total heparin (4,000 international units [IU] vs. 6,000 UI for the non-ACT-guided group; p<0.001) was administered. In addition, in this group, a lower weight-adjusted heparin dose (58 IU/kg vs. 81.7IU/kg; p<0.001) was given.” Furthermore, the ACT-guided group had a significantly lower rate of major bleeding (7.5% vs. 33.5%; p<0.001) and life-threatening bleeding (12.1% vs. 20.2; p=0.04) compared with the non-ACT-guided group. The authors add: “After adjustment for baseline cofounders, the absence of baseline ACT guidance (p<0.001) and baseline estimated glomerular filtration rate (p=0.04) were the only predictors of 30-day major bleeding. Importantly, irrespective of the time the procedure was performed, the ACT-guided strategy was associated with a significantly lower occurrence of major bleeding.”


According to the authors, “simple” weight-adjusted heparin administration does not take into account several factors that may affect a patient’s response to heparin and, therefore, risks potential “overdosing in these particularly frail patients”. They explain: “The elderly TAVI study group is generally more vulnerable to the adverse effect of antithrombotic drugs, particularly bleeding. Factors that may affect therapeutic agents (eg. renal function) as well as factors more specific to haemostasis (eg. platelet dysfunction) may partially account for such higher vulnerability to the side-effects of antithrombotic medications.”


Concluding, they say that baseline ACT values may be an “effective tool in guiding heparin administration during transfemoral TAVI. Further randomised studies are warranted to determine whether heparin should be given according to baseline ACT guidance and to confirm the usefulness of this strategy in reducing bleeding.”