ABSTRACT OBJECTIVES The quality of prehospital resuscitation provided by emergency medical technicians (EMTs) is essential to ensure better outcomes following out-of-hospital cardiac arrests (OHCA). We assessed the quality of prehospital resuscitation by recording time to key prehospital interventions using EMT-worn video devices and investigated its association with outcomes of patients with OHCA. METHODS This retrospective, cross-sectional study included cases of non-traumatic OHCA in adults treated by EMS in Hsinchu City, Taiwan, during 2022 and 2023. We used data from high-resolution, chest-mounted wearable cameras to define and measure six Quality Indices (QIs) for prehospital resuscitation interventions (i.e., time spent recognizing OHCA). To evaluate the association between QI performance and sustained return of spontaneous circulation (ROSC), we used multivariable logistic regression. RESULTS Of 745 patients eligible for this study, 187 (25.1%) achieved sustained ROSC. Six core QIs were analyzed: recognition of OHCA (median time: 9.0 seconds), time from recognizing OHCA to initiating cardiopulmonary resuscitation (CPR; 9.0 seconds), automated external defibrillator setup (34.0 seconds), time from recognizing OHCA to beginning ventilation (160.0 seconds), advanced airway management (300 seconds), and deploying a mechanical CPR device (50 seconds). The performance of the six QIs were not associated with sustained ROSC (Adjusted odds ratio [95% confidence interval]: 1.00 [0.99-1.00], 0.99 [0.98-1.00], 1.00 [1.00-1.01], 1.00 [1.00-1.00], 1.00 [1.00-1.00] and 0.99 [0.99-1.00], respectively). CONCLUSIONS This study describes the rate of sustained ROSC and time to key interventions captured by EMT-worn video devices in non-traumatic OHCA patients. Although we found no direct link between QI performance and improved OHCA outcomes, this study highlights the potential of video-assisted QIs to enhance the documentation and understanding of prehospital resuscitation processes. These findings suggest that further refinement and application of these QIs could support more effective resuscitation strategies and training programs.