This study is limited by its observational nature and lack of randomization. Surprisingly, more individuals were intubated in the MICR groups. For hospitalists, the results could have a dramatic affect on cardiac arrest survival and lead to future changes to CPR/ACLS protocols.
Bottom line: MICR has a significant impact on survival in out-of-hospital cardiac arrest as compared with traditional CPR and ACLS.
Citation: Bobrow B, Clark L, Ewy G, et al. Minimally interrupted cardiac resuscitation by emergency medical services for out-of-hospital cardiac arrest. JAMA. 2008;299(10):1158-1165.
Does Lower aPTT Increase Future VTE Independent of Other Pro-coagulant Factors?
Background: Certain factors, such as obesity, D-dimer levels, and factor V Leiden gene mutations, increase the risk of future venous thromboembolism (VTE) events. This study sought to determine whether lower baseline levels of activated partial thromboplastin time aPTT also increase this risk.
Study design: Prospective multicenter cohort study.
Setting: Longitudinal Investigation of Thromboembolism Etiology research study (Atherosclerosis Risk in Communities portion) in four U.S. communities.
Synopsis: 13,880 individuals with baseline aPTT measurements were followed for 13 years for future VTE events. Of those, 260 developed a VTE of which 111 were described as idiopathic. Individuals in the lowest two quartiles of aPTT compared with the highest fourth quartile had a 2.4-fold and 1.9-fold increase in the risk of VTE, respectively. A lower aPTT further increased the risk of VTE when associated with obesity, elevated D-dimer level, and particularly factor V Leiden.
This study was limited by the relatively small number of VTE events. It also did not clarify whether aPTT measurements in high-risk groups such as those with positive family history of VTE were useful for predicting risk of future VTE. For hospitalists, patients with a lower initial aPTT may warrant more aggressive inpatient DVT prophylaxis.
Bottom line: aPTT below the median level increases the risk of future VTE events, especially if associated with obesity, elevated D-dimer levels, and/or factor V Leiden.
Citation: Zakai NA, Ohira T, White R, Folsom A, Cushman M. Activated partial thromboplastin time and risk of future venous thromboembolism. Am J of Med. 2008;121:231-238.
What Bleeding Outcomes are Associated with Using Warfarin with Antiplatelet Agents?
Background: Despite a high prevalence of combining antiplatelet and warfarin therapy, the timing, safety, and efficacy of this strategy remain controversial.
Study design: Retrospective cohort study.
Setting: Kaiser Permanente Colorado.
Synopsis: Using a pharmacy database, the authors identified 2,560 patients receiving warfarin alone (monotherapy cohort) and 1,623 patients receiving warfarin combined with antiplatelet agents (combination therapy cohort).
In the combination therapy cohort, aspirin was the most common antiplatelet agent (37%) followed by clopidogrel (13%) and dipyridamole (2%). During a six-month period, the combination therapy cohort had a 4.2% risk of hemorrhage and a 2.0% risk of major hemorrhage. Warfarin monotherapy was associated with a 2% risk of hemorrhage and 0.9% risk of major hemorrhage.
At baseline, the combination therapy patients were twice as likely to have diabetes or congestive heart failure and four times as likely to have coronary artery disease. In both cohorts, the most common reason for warfarin therapy was atrial fibrillation.
Since this was a retrospective investigation, hospitalists should be careful about drawing conclusions from this study alone, but are reminded to discuss risks carefully and engage in shared decision-making with patients when using combined warfarin and antiplatelet therapy.
Bottom line: Warfarin use in combination with antiplatelet therapy is associated with more than double the risk of bleeding compared with warfarin monotherapy.
Citation: Johnson SG, Rogers K, Delate T, Witt DM. Outcomes associated with combined antiplatelet and anticoagulant therapy. Chest. 2008;133:948-954.