EXECUTIVE SUMMARY: Evaluations of improvements in long chronic-patient pathways must include both short- and long-term effects on patients; that is, effects on the full patient pathway. Otherwise, costs might be cut without considering the long-term effects and, consequently, the overall cost of the pathway could increase. Unfortunately, current methods of evaluation present several issues: (1) they do not provide valid insights regarding the effects of a given improvement effort until several years later, (2) they provide imprecise and biased results, and (3) the aggregated results are not useful for identifying and disseminating the best practices that lead to an improvement. In this article, the accelerated longitudinal design with decomposition of total costs (ALDD) method is applied to evaluate the effects of improvement efforts on inpatient utilization for long cardiac pathways at a Danish hospital. The results show that the ALDD method can deliver valid results much faster than traditional methods and can uncover hidden improvements in the local work processes of clinical teams. Application of the ALDD method at a hospital in Denmark identified a significant reduction (15.4%) in the mean total bed utilization per cardiac pathway and revealed that this reduction was caused by improvements in the work processes.