Pharmacist involvement in clinical assessment and laboratory testing for heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a rare adverse drug reaction. The anti-PF4 antibody assay (ELISA) is utilized to assist in the clinical evaluation of HIT due to its high negative predictability and wide-spread availability. However, it also associated with false positive results. The 4T score can assist in predicting an individual's risk for HIT and the need for further laboratory testing. This was a single-center prospective observational cohort study. Orders for HIT testing were sent via page to a clinical pharmacist to calculate a 4T score. If low risk, the pharmacist contacted the ordering prescriber to recommend discontinuation of laboratory testing. During the study, a clinical support tool was implemented to assist prescribers with ordering HIT tests. The study was divided into a pharmacist intervention group and a control group. A total of 303 pages were received. One hundred nine were missed due to unavailability of the pharmacist at time of page. A pharmacist reviewed 194 pages and intervened on 132. One hundred seven were scored as low risk, 70 as intermediate risk and 9 as high risk. Pharmacist intervention resulted in discontinuing 64 ELISA and 11 serotonin release assay tests. The clinical support tool resulted in a yearly decrease of HIT testing by 27%. Laboratory cost savings totaled $11,000 but did not include avoidance of laboratory technician or drug cost. Pharmacist involvement in the clinical assessment of HIT and the use of a support tool resulted in the reduction of HIT tests in low risk patients.

Analysis of anticoagulant prescribing in non-valvular atrial fibrillation and development of a clinical tool for guiding anticoagulant selection.

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the United States. Traditionally, warfarin has been used to prevent the occurrence of stroke in intermediate-to-high risk patients. Target-specific oral anticoagulants (TSOACs) have become a favorable alternative; however, recommendations for differentiating between the available TSOACs were lacking within the 2012 CHEST guidelines. The objective of this retrospective, observational study was to identify current anticoagulation prescribing habits in patients admitted with new-onset AF, and evaluate the appropriateness of discharge therapy based on national guidelines. Additionally, a practice guideline was created for use at our institution to stratify appropriate use of TSOACs. Patients were included if they were at least 18 years old and were admitted with a primary diagnosis of new-onset, non-valvular AF between July 1, 2012 and June 30, 2013. CHADS2, CHA2DS2VASc, and HAS-BLED scores were calculated based on patient data. Between July 2012 and June 2013, 143 patients were included in the study. The average CHADS2 score was 1.7, the average CHA2DS2VASc score was 3.0, and the average HAS-BLED score was 2.4. The use of no antithrombotics decreased as the CHA2DS2VASc score increased, aspirin use stayed consistent across risk groups, warfarin use increased as the CHA2DS2VASc score increased, and TSOAC use decreased with increasing CHA2DS2VASc score. A total of 34 % of study patients were prescribed inappropriate treatment upon discharge, based on national guidelines. This study demonstrated that patients admitted to our hospital were prescribed appropriate therapy the majority of the time; however, 34 % were prescribed inadequate antithrombotic therapy compared to current practice guidelines given their CHA2DS2VASc score. The development of an institution-specific guideline stratifying appropriate use of anticoagulation in this population may increase adherence to national guideline recommendations.

Antithrombotic selection in patients undergoing transcatheter aortic valve replacement.

PURPOSE: Clinical controversy regarding the most appropriate antithrombotic regimen after transcatheter aortic valve replacement remains. Current evidence, guidelines, and recommendations are discussed. SUMMARY: Antithrombotic selection following transcatheter aortic valve replacement depends on a variety of patient-specific factors. For patients without a preexisting indication for anticoagulation, initial trials employed dual antiplatelet therapy as the postprocedural therapy of choice. Newer studies in this patient population, however, suggest single antiplatelet therapy reduces bleeding events without sacrificing ischemic protection. In patients with a preexisting indication for anticoagulation, warfarin plus single antiplatelet therapy, as opposed to triple antithrombotic therapy, offered similar ischemic protection while reducing clinically significant bleeding. Warfarin monotherapy was associated with a further reduction in bleeding events. One trial demonstrated the safety and efficacy of using apixaban in patients with concomitant atrial fibrillation; however, routine use of rivaroxaban increased adverse cardiac and bleeding events, leaving the utility of direct-acting oral anticoagulants in question. CONCLUSION: Available evidence and current guidelines point to a lack of consensus regarding antithrombotic selection after transcatheter aortic valve replacement. Patient-specific factors and comorbidities must be considered when tailoring therapy, with an emphasis on balancing thrombotic and bleeding risks.

Successful use of fondaparinux early after mechanical aortic valve replacement in a patient with a history of heparin-induced thrombocytopenia.

Thromboembolic complications such as systemic embolization and valve thrombosis are a major concern early after mechanical valve replacement; however, the benefit of anticoagulation must be weighed against the risk of early postoperative bleeding complications. Thromboembolic risk is also higher in the early postoperative period (less than 6 mo) compared with the risk in the late postoperative period. Current evidence supports the use of unfractionated heparin or low-molecular-weight heparin early after valve replacement to prevent valve thrombosis or systemic embolization but provides no recommendations for the management of patients with a history of heparin-induced thrombocytopenia (HIT), in which heparin products are contraindicated. We describe the use of fondaparinux early after aortic mechanical valve replacement in a 63-year-old, 95-kg woman with a history of HIT. Fondaparinux was initiated on postoperative day 2 at a prophylactic dose of 2.5 mg subcutaneously daily; the dose was increased to a therapeutic weight-based dose of 7.5 mg subcutaneously daily on postoperative day 3. Warfarin was initiated on postoperative day 1, and fondaparinux was continued until a therapeutic international normalized ratio was achieved. The patient was discharged from the hospital receiving warfarin alone on postoperative day 6. No signs or symptoms of thrombosis or bleeding were noted during or after fondaparinux therapy or at hospital follow-up visits. To our knowledge, this is the first case report to describe the use of fondaparinux within the first 48 hours after mechanical valve replacement in a patient with a history of HIT. This case suggests that fondaparinux may be a safe and effective option to prevent thromboembolic complications early after mechanical valve replacement when heparin products are contraindicated.