PB0421 - Prevalence of Guideline Discordant Aspirin use and Associated Adverse Events in Patients on Warfarin for Mechanical Valve Replacement

Sunday, July 10, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Co-Author(s)

BH

Brian Haymart

Nurse and project leader
Michigan Medicine
Ann Arbor, Michigan, United States
XK

Xiaowen Kong

Statistician
Michigan Medicine
Ann Arbor, Michigan, United States
Geoffrey Barnes, MD, MSc

Cardiologist and Vascular Medicine Specialist
Michigan Medicine
Ann Arbor, Michigan, United States
JE

Josh Errickson

Statistician
University of Michigan
Ann Arbor, Michigan, United States
EK

Eva Kline-Rogers

Nurse Practitioner
University of Michigan Health
Ann Arbor, Michigan, United States
MA

Mona Ali

Pharmacist
Beaumont Hospital
Royal Oak, Michigan, United States
VS

Vinay Shah

Physician
Henry Ford Health System
Detroit, Michigan, United States
JF

James B Froehlich

Professor of Internal Medicine
University of Michigan Health
Ann Arbor, Michigan, United States

Presenting Author(s)

Scott Kaatz, DO, MSc

Hospitalist
Henry Ford Health
Detroit, Michigan, United States

Background: For patients on vitamin K antagonists for mechanical aortic or mitral valve replacements, the 2020 American College of Cardiology and American Heart Association Valvular Heart Disease Guidelines recommend only adding aspirin in patients with a specific indication for antiplatelet therapy. This is in contrast to prior guidelines which recommended concomitant aspirin therapy.

Aims: To assess the prevalence of guideline discordant aspirin use among patients with mechanical heart valves on warfarin and to compare adverse event rates among patients with and without concomitant aspirin.

Methods: Patients on warfarin for mechanical heart valve replacement were identified from the Michigan Anticoagulation Quality Improvement Initiative (MAQII) registry. Patients with an indication for antiplatelet therapy, including myocardial infarction, percutaneous coronary intervention, or coronary artery bypass within the past 12 months, were excluded. Aspirin and non-aspirin cohorts were formed based on aspirin use at enrollment. Demographics and co-morbidities were compared using t-test and chi-square test while bleeding and thrombotic rates were compared using Poisson regression model. HAS-BLED (bleeding risk) and CHA2DS2-VASc (ischemic stroke risk) scores were used to adjust event rates.

Results: A total of 182 patients met inclusion criteria, with 121 (66.5%) using aspirin (Table 1). The cohorts had similar demographics, time in therapeutic INR range, and HAS-BLED and CHA₂DS₂-VASc scores. The aspirin cohort had a significantly higher rate of bleeding (25 vs 12 per 100 patient-years, p< 0.001) and emergency department visits for bleeding (14.1 vs 3.6 per 100 patient-years, p< 0.001) compared to the non-aspirin cohort. There was no observed difference in rates of ischemic stroke between the cohorts (0.21 vs 0.40 per 100 patient-years, p=0.69).

Conclusion(s): A significant proportion of patients on warfarin for mechanical valve replacement are on guideline discordant aspirin therapy. Aspirin de-prescribing may safely reduce bleeding events and emergency department utilization.