Effectiveness of Cardiopulmonary Exercise Testing as an Incentive to Enhance Outpatient Cardiac Rehabilitation Participation in Acute Coronary Syndrome Survivors: A Study Protocol for a Randomized Controlled Trial with Determinant Analysis

Background: Despite clear evidence supporting the benefits of outpatient cardiac rehabilitation for acute coronary syndrome survivors, participation rates remain low. Many patients face person-level and system-level barriers for outpatient rehabilitation, and their motivation often wanes soon after discharge. Cardiopulmonary exercise testing provides individualized physiological information and may act as an external cue that enhances engagement, yet no randomized trial has evaluated whether announcing a scheduled test can influence rehabilitation attendance. Methods: This single-center, parallel-group, single-blind randomized controlled trial investigates whether informing patients during hospitalization that a cardiopulmonary exercise test will be conducted at their first rehabilitation visit increases early outpatient attendance. Patients with acute coronary syndrome are randomized 1:1 to receive either standard discharge education or the same education plus an exercise testing announcement. All other clinical care follows routine practice. The primary endpoint is completion of the first rehabilitation clinic visit within 30 days. Secondary outcomes include attending at least six rehabilitation sessions within 12 weeks, actual exercise testing completion, and any safety events. The analyses will follow the intention-to-treat principle and will use logistic regression and time-to-event models. The planned sample size is 200 participants.