BACKGROUND: Patients with a left ventricular ejection fraction ≤ 35% are at increased risk of sudden cardiac death (SCD) within the first months after a myocardial infarction (MI). The wearable cardioverter defibrillator (WCD) is an established, safe and effective solution which can protect patients from SCD during the first months after an MI, when the risk of SCD is at its peak. This study aimed to evaluate the cost-effectiveness of WCD combined with guideline-directed medical therapy (GDMT) compared to GDMT alone, after MI in the English National Health Service (NHS). METHODS: A multi-state Markov model, with a hypothetical cohort of 1000 patients, was developed to evaluate WCD + GDMT compared with GDMT alone, over a lifetime time horizon. Model input parameters were obtained from the pivotal randomised controlled trial and literature. The outcomes were costs and quality-adjusted life-years (QALYs), discounted at 3.5% annually, with overall results presented as an incremental cost-effectiveness ratio (ICER). RESULTS: The cost-effectiveness analysis demonstrated that WCD + GDMT is potentially a cost-effective option with an ICER of £23,024 per QALY gained, which is in the acceptable willingness to pay threshold (WTP) range of £20,000-£30,000 set by the National Institute for Health and Care Excellence (NICE) in England. Results of probabilistic sensitivity analysis (PSA) indicated that WCD + GDMT has 89.3% and 23% probability of being cost-effective at WTP thresholds of £30,000 and £20,000, respectively. CONCLUSIONS: Implementation of WCD in patients post-MI is potentially a cost-effective use of resources for the NHS and improves clinical outcomes amongst adherent patients and in circumstances where implantable cardioverter defibrillators are not indicated by the guidelines.