Deferred Versus Immediate Stent Implantation for Preventing Microvascular Dysfunction and Improving Clinical Outcomes in Patients With ST-Segment Elevation Myocardial Infarction (SALVAGE)

Brief Summary

Detailed Description

Methodology: A multicenter, prospective, randomized, controlled clinical study enroll patients with ST-segment elevation myocardial infarction (STEMI) intended for PCI with stenting implantation. Eligible patients are randomly assigned to the immediate stenting group or delayed stenting group in a 1:1 ratio when residual stenosis \>70% and TIMI grade 3 with angiography guidance. The index of microcirculation resistance (IMR) is quantitative analysis by an invasive approach for evaluating post-infarct myocardial microcirculatory perfusion. IMR correlates with the infarct size of patients with acute myocardial infarction and predicts the improvement in left ventricular ejection fraction. Studies have shown that acute myocardial infarction patients with IMR \>40 after primary PCI predict adverse long-term clinical outcomes with higher mortality and heart failure rehospitalization rates. According to therapeutic strategies and microvascular function detected by IMR, participants are classified into four groups: immediate stenting with IMR ≥ 40, immediate stenting with IMR \< 40, deferred stenting with IMR ≥ 40 and deferred stenting with IMR \< 40. All randomized patients will be followed by phone call or clinical visit at 12 months. Patient enrollment and procedure overview: Patients aged from 18 to 80 with STEMI\<12h in whom PCI is planned will be screened. Thrombectomy and balloon dilatation will be performed at the operator's discretion to restore an effective antegrade blood flow with TIMI flow grade 3. Patients with residual diameter stenosis \>70% visually and TIMI blood flow grade 3 are eligible for including in the study. All patients must provide written informed consent and patients will be randomized to immediate stenting group or deferred stenting group in a 1:1 ratio. All participants in immediate stenting group will be treated with stent implantation immediately. Those assigned to the deferred arm will undergo stenting after an interval of 7±2 days. This interval will be bridged with anti-coagulant and anti-platelet therapy to reduce thrombus burden. All patients in both groups are required to take dual antiplatelet treatment while the application of low molecular weight heparin and glycoprotein IIb/IIIa inhibitor are determined by the operators. All participants are required to perform IMR pre-stenting and post-stenting to evaluate microcirculation function. All randomized patients will be followed up to 12 months to evaluate the prevalence of heart failure, all-cause mortality, recurrent infarction or targeted vessel revascularization. Study follow-up: Clinical follow-up: Participants will be followed by phone calls or clinical visits by study coordinators at 1 month (+/-7 days), 3 months (+/-15 days), 6 months (+/-15 days), 9 months (+/-15 days) and 12 months (+/-30 days) after randomization. Major adverse cardiovascular events (MACEs) will be recorded throughout the study period until last patient has been followed for 12 months.

Primary Outcomes

Secondary Outcomes

• Peaks of CK, CK-MB, cTnI and area under CK curve(through hospitalization, an average of 7 days)
• Peri-procedural myocardial reperfusion reinjury(through hospitalization, an average of 7 days)
• Procedural success and clinical success(postprocedure and through hospitalization, an average of 7 days)
• ECG ST-segment resolution at 90 minutes after primary PCI(90 minutes postprocedure)
• LVEF detected by echocardiographic indices at 7 days after stenting, 1 month and 12 months after discharge(7 days, 1 month and 12months)
• Hospitalization due to heart failure(1 year)
• Contrast score index and myocardial blood flow detected by myocardial contrast echocardiography 7 days after stenting and 1 month after discharge(7 days and 1 month)