Efficacy of an Embolic Protection Stent as a Function of Delay to Reperfusion in ST-Segment Elevation Myocardial Infarction (from the MASTER Trial)

• We performed a prespecified analysis of the MASTER trial (patients with ST-segment elevation myocardial infarction, primary percutaneous coronary intervention [PCI]).
• We evaluated the impact of delay to primary PCI according to the type of stent placed.
• We compared the MGuard embolic protection stent and conventional stents (drug-eluting stent and bare-metal stent).
• Complete ST resolution after PCI was more frequent in patients with shorter delay to PCI.
• The MGuard stent tended to be particularly beneficial in patients with delay to PCI >3 hours.

The ability of stent implantation to improve indexes of reperfusion may depend on the time to reperfusion in acute ST-segment elevation myocardial infarction (STEMI) and may also vary with stent type. The purpose of this prespecified analysis from the randomized MGUARD for Acute ST Elevation Reperfusion trial was to evaluate the impact of delay to reperfusion on outcomes in patients with STEMI undergoing primary percutaneous coronary intervention with the MGuard embolic protection stent or standard metallic stents. A total of 431 patients were divided according to symptom-onset-to-balloon time (SBT) into 2 groups: SBT ≤3 hours (167 patients; 39%) and SBT >3 hours (264 patients; 61%). Complete ST-segment resolution (STR) after percutaneous coronary intervention was more often achieved in patients with shorter SBT (58.6% vs 47%, p = 0.02). At 1 year, the all-cause mortality rate was lower in patients with shorter SBT (0% vs 3.5%, p = 0.02). STR was achieved in 58% of MGuard patients and in 45% of the control stent patients (p = 0.008). STR was 57% in the MGuard group versus 38% in the control group (p = 0.002 for SBT >3 hours) and 60% versus 57% (p = 0.72), respectively, for SBT ≤3 hours (p for interaction = 0.11). In conclusion, longer delay to mechanical reperfusion remains an important factor negatively influencing outcomes in patients with STEMI. Use of the MGuard embolic protection stent compared with conventional metallic stents resulted in superior rates of complete STR, even in patients with longer delays to reperfusion.