Abstract 14: Use of an Insertable Cardiac Monitor to Detect Atrial Fibrillation is Cost Effective in Patients with Cryptogenic Stroke

Abstract

Introduction: The cause of ischemic stroke remains uncertain (cryptogenic stroke) in 20-40% of cases despite conventional diagnostic tests. Documentation of atrial fibrillation (AF) is required to initiate anticoagulant therapy to reduce recurrent stroke risk, however, the paroxysmal and asymptomatic nature of AF means it is often not detected with traditional monitoring techniques. We assessed the hypothesis that detecting AF via continuous long-term monitoring with an insertable cardiac monitor (ICM) is cost effective for preventing recurrent stroke in cryptogenic stroke patients, in comparison to Standard of Care (SoC). Methods: A randomized controlled trial reported a nine-fold increase in AF detection with an ICM (Reveal XT, Medtronic) compared to SoC over 3 years follow-up, after exclusion of patients with evidence of AF from initial tests. A lifetime Markov model was developed which uses trial data to estimate cost effectiveness of ICM from a U.K. NHS perspective. The CRYSTAL AF study provided AF detection rates, ICM implant complications, resource use and baseline quality of life. Safety and efficacy data for specific non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin were sourced from literature to estimate stroke and bleeding risks. Other quality of life and cost data were sourced mainly from the UK OXVASC study. All costs and benefits were discounted at 3.5% and scenario analyses (CHADS2 score) and probabilistic sensitivity analyses (PSA) were conducted. Results: ICM was associated with fewer recurrent strokes and increased Quality Adjusted Life Years (QALYs) compared to SoC. Stroke-related costs were reduced in the ICM arm, however, overall costs did remain higher than SoC. The incremental cost-effectiveness ratio (ICER) was below a £30,000 per QALY gained willingness-to-pay threshold. Sensitivity analysis indicated that the ICER increased in patients with lower CHADS2 scores, however, it remained below the threshold. Conclusion: AF detection with ICM increases linearly over its 3 year life, identifying AF in nine-fold more patients than SoC. ICM appears to be a cost-effective diagnostic tool for the prevention of recurrent stroke in patients with cryptogenic stroke in the UK and countries with similar healthcare systems.