Quality metrics for both laboratory and operator performance and considerations with regard to primary PCI at hospitals without on-site cardiac surgery are reviewed in the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coro- nary Intervention, Section 7.219 Table 2. Primary PCI in STEMI COR LOE References Ischemic symptoms <12 h and contraindications to fibrinolytic therapy irrespective of time delay from FMC Cardiogenic shock or acute severe HF irrespective of time delay from MI onset I B 212 215 Evidence of ongoing ischemia 12 to 24 h after symptom onset PCI of a noninfarct artery at the time of primary PCI in patients without hemodynamic compromise III: Harm B 216 218 COR indicates Class of Recommendation; FMC, first medical contact; HF, heart failure; LOE, Level of Evidence; MI, myocardial infarction; PCI, percutaneous coronary intervention; and STEMI, ST-elevation myocardial infarction. O Gara et al 2013 ACCF/AHA STEMI Guideline e375 Potential complications of primary PCI include problems with the arterial access site; adverse reactions to volume loading, contrast medium, and antithrombotic medications; technical complications; and reperfusion events. The no- reflow phenomenon refers to suboptimal myocardial perfu- sion despite restoration of epicardial flow in the infarct artery and has been attributed to the combined effects of inflam- mation, endothelial injury, edema, atheroembolization, vasospasm, and myocyte reperfusion injury.220 No-reflow is associated with a reduced survival rate. Treatment and prevention strategies have included use of the GP IIb/IIIa antagonist abciximab, vasodilators (nitroprusside, vera- pamil, adenosine), and inhibitors of various metabolic path- ways (nicorandil, pexelizumab), albeit without consistent effect. 