Cardiac arrest is a life-threatening emergency that requires immediate and competent response from healthcare professionals. In South Korea, heart disease ranks among the top three causes of death and in-hospital cardiac arrest (IHCA) survival rates remain low, with favorable neurological outcomes reported in fewer than 15 % of cases (Wiberg et al., 2020). Timely and accurate implementation of advanced life support (ALS) during IHCA is essential for improving patient outcomes. Among healthcare providers, nurses are often the first responders due to their continuous presence at the bedside, which underscores the importance of maintaining ALS competency in nursing education and practice (Guetterman et al., 2019).

The Korean Advanced Life Support (KALS) program, developed by the Korean Association of Cardiopulmonary Resuscitation (KACPR, 2017), provides structured training in ALS knowledge and skills, including defibrillation, rhythm recognition, airway management and team-based decision-making (KACPR, 2021). However, nursing students and newly graduated nurses exhibit a marked decline in ALS knowledge and skill retention within 3–6 months after initial training (Anderson et al., 2019). Given this rapid skill decay, current AHA guidelines recommending retraining every two years (Cheng et al., 2020) may be too long to ensure clinical readiness—particularly for novice practitioners.

To address this challenge of skill decay, several educational frameworks have been proposed. Mastery learning focuses on enabling all learners to reach a high level of competence through structured feedback, formative assessment and repeated practice until mastery is demonstrated (Bloom, 1973, McGaghie et al., 2011). Complementing this approach, deliberate practice emphasizes goal-oriented repetition and immediate feedback to promote skills acquisition and performance refinement (Ericsson, 2008, Ericsson et al., 1993). Recognizing the value of these frameworks, the 2025 American Heart Association Guidelines emphasize the use of deliberate practice, including rapid-cycle deliberate practice and mastery learning principles in cardiopulmonary resuscitation (CPR) retraining to promote achievement of predefined performance standards, enhance skills retention and minimize skills decay over time (Donoghue et al., 2025). Together, these models provide a robust theoretical foundation for designing effective booster training programs in healthcare education.

Despite the theoretical support for these educational frameworks, significant gaps remain in the empirical evidence. Recent studies confirm that high-fidelity simulation effectively enhances CPR competecy; however, most research has examined only immediate training outcomes rather than long-term competency retention (Herrero-Izquierdo et al., 2025). Although booster training has been shown to improve skills retention (Au et al., 2019, Gugelmin-Almeida et al., 2022, Oermann et al., 2020), evidence regarding its effects on knowledge retention (Jeong and Moon, 2024) and teamwork (Bender et al., 2014) is limited and some studies report no significant outcome differences regardless of booster training (Bender et al., 2014, Waldolf et al., 2023). Research on ALS booster training for nursing students is particularly scarce and there is no consensus on optimal timing or format for booster CPR training (Gugelmin-Almeida et al., 2022), underscoring the need for rigorously designed, theory-informed studies to sustain competencies and mitigate skills decay.

To address these gaps, this study aimed to evaluate the effects of a short, theory-based KALS booster training program—structured around mastery learning and deliberate practice—on the six-month retention of ALS-related knowledge, skills performance and teamwork among senior nursing students. We hypothesized that students who received booster training three months after the initial KALS course would demonstrate superior retention of ALS competencies at six months compared with those who did not receive retraining.