Poorly managed anticoagulation may contribute to risk of dementia

Anna GarrettExcellent anticoagulation management appears to lower the risk of dementia over the long term in patients with atrial fibrillation (AF). A study of 2,605 patients tracked an average of four years found an inverse relationship between the percentage of time in the therapeutic range (TTR) of INR and long-term risk of a dementia diagnosis in AF patients.

Patients in the study were managed on warfarin with a target INR of 2 to 3. Their mean age was 74, and 54% were male; 30.5% had a CHADS₂ score of 0 or 1, and about 70% had a CHADS₂ score of 2 or 3.

Over a median of four years of follow-up, the percentage of TTR averaged 63.1%; mean time in INR <2 was 25.6% and mean time in INR >3 was 16.2%. The rate of a dementia diagnosis was 4.2%.

The risk of dementia went up 1.7% for each percentage-point increase in time with an INR <2, and by 1.8% for each percentage-point increase in time with an INR >3.

The authors suggested that these results may be due to the possibility that chronic overanticoagulation and underanticoagulation can produce repeated microemboli and microbleeds that may be below detection thresholds of standard brain imaging but eventually contribute to dementia.

Jacobs V, Woller SC, Stevens S, et al. Time outside of therapeutic range in atrial fibrillation patients is associated with long-term risk of dementia. Heart Rhythm 2014. Published online August 8, 2014. http://bit.ly/ttrAFdement.

Peri-op AF increases long-term risk of stroke

A new study suggests that new-onset perioperative atrial fibrillation during surgery is linked to an increased risk of stroke within a year. New-onset AF is estimated to occur in 1% to 40% of surgeries and is often considered to be a transient response to stress.

Perioperative AF during cardiac surgery has repeatedly been linked with an increased risk of perioperative stroke. However, the risk of ischemic stroke in the long term after new-onset AF during cardiac and noncardiac surgery is unclear.

Of the 1,729,360 eligible patients identified, 24,711 (1.43%) had new-onset perioperative AF during hospitalization and 13,952 (0.81%) experienced an ischemic stroke after discharge, during a mean follow-up of 2.1 years.

Perioperative AF during both cardiac and noncardiac surgery was associated with a greater long-term risk of stroke; however the association of perioperative AF with stroke was significantly stronger with noncardiac surgery.

Gialdini G, Nearing K, Bhave P, et al. Perioperative atrial fibrillation and the long-term risk of ischemic stroke. JAMA. 2014; 312(6):616-622. http://bit.ly/periopAF.

Discharge aspirin dosing does not match latest U.S. guidelines

American doctors may be putting their myocardial infarction (MI) patients at risk because they have not kept up with changes in practice guidelines pertaining to aspirin dose post-MI. Many U.S. patients who have an MI are discharged with high-dose aspirin, even though the latest evidence-based practice guidelines support the use of low-dose (81 mg) aspirin. Earlier U.S. guidelines recommended higher doses, but the 2012–2013 guidelines now advocate low-dose aspirin.

Researchers in this study identified 221,199 patients, 40% with STEMI and 60% with non-STEMI, who were seen in 525 centers from 2007 to 2011 and received aspirin on discharge. Most patients (60.9%) received high-dose aspirin; fewer (35.6%) received low-dose aspirin. Patients receiving doses other than 81 mg or 325 mg were excluded from analysis.

Patients undergoing PCI had the highest prevalence of high-dose aspirin at discharge (73%), followed by patients receiving PTCA alone (66%), CABG (48%), and medical management alone (44%). Post-CABG treatment is among the only cardiovascular situations where high-dose aspirin continues to be endorsed by guidelines (100–325 mg daily, class 1A).

Previous U.S. guidelines recommended high-dose aspirin at discharge for patients receiving intracoronary stents, based on protocols from early pivotal stent trials, and these were likely a major contributor to the practice pattern, the researchers said.

Hall HM, de Lemos JA, Enriquez JR, et al. Contemporary patterns of discharge aspirin dosing after acute myocardial infarction in the United States: Results From the National Cardiovascular Data Registry. Circulation: Cardiovascular Quality and Outcomes 2014. Published online before print August 12, 2014. http://www.ncbi.nlm.nih.gov/pubmed/25116897.