Percutaneous coronary intervention (PCI) has become one of the main treatments for rapid recovery of revascularization in patients with coronary heart disease (CHD). PCI has some advantages, such as easy operation, small trauma and rapid recovery. It can significantly improve myocardial ischemic symptom and reduce the incidence of cardiovascular adverse events in CHD patients. However, many studies have found that the incidence of PCI-related myocardial injury is relatively high, and affect the efficacy of PCI and prognosis in patients with unstable angina pectoris (UAP). A meta-analysis of a total of 7578 patients with UAP from 15 studies who underwent PCI was found to have a 28.7% increase in myocardial biomarkers after PCI. The objective of this randomized control trial is to gain a clinical insight on the use of low temperature contrast for the treatment of PCI-related myocardial injury in UAP patients. The primary objective is assess efficacy and safety of low temperature contrast for the treatment of PCI-related myocardial injury in UAP patients.

The current study is designed as a multicenter, randomized and prospective study aiming to compare the change in levels of myocardial injury biomarkers (such as TNI and CK-MB) between low temperature contrast group and room temperature contrast group. Based on previous study, the incidence rate of PCI-related myocardial injury is 28.7% in UAP patients undergoing PCI. And in our study the expected incidence rate of PCI-related myocardial injury is up to 14.3% in UAP patients undergoing PCI after treatment with low temperature contrast. Moreover, the investigators estimated 10% loss follow-up of these patients in each arm. As a result, a total of 440 UAP patients were required, and with 220 patients per group as a ratio of 1:1 randomization.

Inclusion Criteria:

• De novo lesions
• Those who meet the diagnostic criteria of unstable angina pectoris
• New generation drug eluting stent implantation
• Only single coronary artery treated at this time

Exclusion Criteria:

• Those who meet the diagnostic criteria of acute myocardial infarction
• Those who meet the diagnostic criteria of stable angina pectoris
• Patients with cardio-genic shock
• Patients with multiple organ failure
• Patients allergic to contrast
• Patients who can not tolerate dual antiplatelet therapy
• Patients who can't tolerate anticoagulation
• Recently infected patients
• Patients with hepatorenal dysfunction
• Thrombotic lesion of coronary artery
• Chronic total coronary occlusion lesion
• Patients with complex coronary bifurcation requiring two stent strategy
• Severe coronary calcified lesion
• Patients with percutaneous coronary angioplasty
• Patients with directional coronary atherectomy or rotational atherectomy
• Patients with drug coated balloon treatment
• Patients with bioabsorbable vascular scaffold implantation
• Previous percutaneous coronary intervention or coronary artery bypass graft
• Patients with active stage of autoimmune disease