Delayed CPK peak after primary PCI in STEMI: marker of reperfusion quality and short-term outcomes

Time to peak creatine phosphokinase (CPK) has historically been used as a surrogate marker of reperfusion in ST-elevation myocardial infarction (STEMI), but its significance in the contemporary primary percutaneous coronary intervention (PCI) era remains uncertain. We retrospectively analyzed 239 consecutive STEMI patients who underwent primary PCI at Tsukazaki Hospital between January 2021 and December 2024. Patients were categorized according to final post-PCI TIMI flow: TIMI 3 (Group A, n = 194) and non-TIMI 3 (Group B, n = 45). The median time to peak CPK was significantly shorter in Group A compared with Group B (330 vs. 517 minutes, p < 0.001), whereas peak CPK levels did not differ significantly between the groups. At 30 days, the incidence of major adverse cardiovascular events plus congestive heart failure was significantly lower in Group A than in Group B (4.1% vs. 13.3%, log-rank p = 0.01). These findings suggest that optimal post-PCI TIMI 3 flow is associated with faster enzymatic washout and better short-term outcomes, and that time to peak CPK may serve as a simple and clinically useful adjunctive marker of reperfusion quality in STEMI patients.