Background: Person-centred care has been shown to be cost-effective compared to usual care for several diseases, including acute coronary syndrome, in a short-term time perspective (< 2 years). The cost-effectiveness of person-centred care in a longer time perspective is largely unknown. Objectives: To estimate the mid-term cost-effectiveness of person-centred care compared to usual care for patients (< 65) with acute coronary syndrome, using a 2-year and a 5-year time perspective. Methods: The mid-term cost-effectiveness of person-centred care compared to usual care was estimated by projecting the outcomes observed in a randomized-controlled trial together with data from health registers and data from the scientific literature, 3 years beyond the 2-year follow-up, using the developed simulation model. Probabilistic sensitivity analyses were performed using Monte Carlo simulation. Results: Person-centred care entails lower costs and improved effectiveness as compared to usual care, for a 2-year time and a 5-year perspective. Monte Carlo simulations suggest that the likelihoods of the person-centred care being cost-effective compared to usual care were between 80 and 99% and between 75 and 90% for a 2-year and a 5-year time perspective (using a 500,000 SEK/QALY willingness-to-pay threshold). Conclusions: Person-centred care was less costly and more effective compared to usual care in a 2-year and a 5-year time perspective for patients with acute coronary syndrome under the age of 65.