Michelle Christina Johansen, MD
Pennlert J, Asplund K, Carlberg B, Wiklund PG, Wisten A, Åsberg S, and Marie Eriksson M. Antithrombotic Treatment Following Intracerebral Hemorrhage in Patients With and Without Atrial Fibrillation. Stroke. 2015
Pennlert et al. conducted an observational study using the Swedish Stroke Register 2005-2012 with the aim of determining the extent and predictors of initiation of antithrombotic treatment following ICH.
A total of 20,768 patients with a first registered ICH were identified using ICD-10 codes. After excluding for prior ICH diagnosis, death prior to discharge or lack of follow-up 14,045 patients were identified and followed for prescription of antithrombotic therapy. The definition for anticoagulation or antiplatelet therapy was having a dispensed prescription of the medication from a Swedish pharmacy after discharge. Additional demographic data (ICD 10) included hypertension, atrial fibrillation (AF), diabetes and prior ischemic stroke. ICD 10 codes were also used when calculating CHA2DS2-VASc and HAS-BLED scores. Notably congestive heart failure was given points only when the patient had been hospitalized due to a primary diagnosis of heart failure. Due to inability to confirm a labile INR, the HAS-BLED score was modified in consideration of this limitation.
The investigators found that at the time of the ICH, 1454 patients (10.4%) were on anticoagulants, 4018 patients (28.6%) were on antiplatelet drugs, and 132 patients (0.9%) were on both drugs. In the AF population, 1055 patients (43.6%) were dispensed an antiplatelet agent and 258 (11.1%) an anticoagulant by one year after ICH. When comparing this to the population at six months, the numbers were lower with 8.5% on anticoagulants and 36.6% on antiplatelet therapy.
What influenced physicians in prescribing patients with AF anticoagulation? Less severe ICH, younger age, previous anticoagulation, valvular disease, and prior ischemic stroke was significantly associated with anticoagulation. High CHA2DS2-VASc scores did not correlate with anticoagulant treatment but there was an interaction between CHA2DS2-VASc scores and HAS-BLED. When looking at resumption of anticoagulation, patients with concurrent AF were less likely to be restarted on drug than those without AF.
How should the results of this study influence the practicing neurologist? It is clear that there is no consensus when prescribing anticoagulation in patients with AF and that physician tend to shy away from use especially in the first six months. Is this the appropriate response? We know that anticoagulation for AF decreases risk of stroke with CHA2DS2-VASc suggesting 3% risk at 1 year if greater than 1, yet providers appear not to be using this tool to guide decision making. Is this presumed fear of hurting patients warranted? A recent cohort study in Canada did not show an increased mortality or bleeding events after ICH with reinitiating of Warfarin and Majeed et al. in Stroke 2010 suggested that optimal timing for Warfarin after ICH was 10-30 weeks, less than the 6 month data point captured in this trial. While it is important to recognize the limitations of this study (observational, adjusted risk scores etc.), the results should nevertheless refocus the neurologist on the importance of appropriate initiation of anticoagulation in the AF population, even after ICH. Future randomized studies are warranted to enable us to further investigate this complex relationship.