One-year outcomes of a single bolus r-SAK before primary PCI for STEMI: Follow-up of the OPTIMA-5 study

The OPTIMA-5 study demonstrated that a single bolus of half-dose recombinant staphylokinase (r-SAK) before primary percutaneous coronary intervention (PCI) significantly improved the patency of infarct related artery in patients with ST-elevation myocardial infarction (STEMI) expected to undergo PCI within 120 minutes. This study aimed to investigate the 1-year clinical outcome and the effect of the r-SAK antibody on a second r-SAK thrombolysis in OPTIMA-5 patients. The clinical outcome was major adverse cardiovascular events (MACE) within 360 days. Patients' r-SAK antibodies were determined on days 90 ± 7, 180 ± 7, and 360 ± 14 after thrombolysis, and <i>in-vitro</i> r-SAK antibody neutralization experiments were performed to explore an optimal interval for a second r-SAK thrombolysis. Results showed that the MACE incidence was numerically lower in r-SAK group compared with normal saline (NS) group (14.0% <i>vs</i>. 20.0%, HR 0.67, 95% CI: 0.34-1.32; log-rank <i>P</i>=0.245). The r-SAK antibody levels in r-SAK group decreased by time, but kept significantly higher than those in NS group on days 90 ± 7 (2.96 ± 0.68 <i>vs</i>. 0.22 ± 0.53, <i>P</i><0.001), 180 ± 7 (2.19 ± 0.74 <i>vs</i>. 0.44 ± 0.65, <i>P</i><0.001) and 360 ± 14 (1.73 ± 0.97 <i>vs</i>. 0.37 ± 0.71, <i>P</i><0.001). The <i>in-vitro</i> r-SAK antibody neutralization experiments illustrated that the thrombolysis rate decreased exponentially as the antibody titer increased from 1.90 to 2.20 (67.80 ± 14.19% <i>vs</i>. 44.32 ± 21.54%, <i>P</i>< 0.0001). Therefore, for STEMI patients expected to undergo PCI within 120 minutes, a single bolus of half-dose r-SAK before primary PCI may reduce 1-year MACE risk. The r-SAK antibody lasts over 1 year, and a second r-SAK thrombolysis may not be indicated until 1 year after the first r-SAK thrombolysis if necessary.