In a preplanned secondary analysis of the AMCPR trial, Kim et al. evaluated whether invasively measured diastolic blood pressure (DBP) and end-tidal CO2 (ETCO2) during adult out-of-hospital cardiac arrest predict sustained return of spontaneous circulation (ROSC). The cohort comprised 264 patients (median age 74 years; 69.3% male). DBP was recorded at arterial-line placement (within ~5 minutes) and again at a follow-up time point (~10 minutes); delta DBP defined as follow-up minus initial. ETCO2 was measured after intubation. The primary outcome was sustained ROSC (≥20 minutes of palpable pulse). Of the 264 patients, 101 (38.3%) achieved sustained ROSC, 24 (9.1%) survived to hospital discharge, and 5 (2.0%) had good neurological recovery. Compared with no-ROSC, the ROSC group had a higher follow-up DBP (34 vs 17 mmHg), whereas follow- up ETCO2 was only modestly higher (16 vs 14 mmHg). Follow-up DBP showed the best discrimination for ROSC (AUROC 0.83), followed by delta DBP (AUROC 0.75). Pragmatic cut points derived by Youden index: follow-up DBP >27 mmHg (sensitivity 73.5%, specificity 83.8%) and delta DBP ≥7 mmHg (specificity 85.2%)—outperformed ETCO₂-based thresholds. A DBP increase ≥7 mmHg provided additional prognostic value with higher specificity (85.2%). In multivariable models, follow-up DBP >26.5 mmHg (adjusted OR 10.03; 95% CI 3.64–27.66) and delta DBP >6.5 mmHg (adjusted OR 4.83; 95% CI 1.90–12.26) independently predicted ROSC, underscoring DBP as the more informative physiologic marker during CPR. Follow-up and increase in DBP during CPR were statistically significant independent predictors of sustained ROSC, whereas ETCO₂ provided only modest, non-significant additional discrimination. In busy adult resuscitations, early invasive DBP monitoring was feasible and clinically informative in this study. These findings support larger multicenter trials to test DBP-guided protocols, refine target ranges, and integrate DBP with vasopressor titration and ETCO2 for outcome-focused CPR.