Percutaneous coronary intervention (PCI) remains the major revascularization strategy for patients with obstructive coronary artery disease (CAD).However,in a substantial number of PCI cases for acute coronary syndrome (ACS) and chronic coronary syndrome (CCS),periprocedural myocardial injury or myocardial infarction (MI) occurs,both these PCI-related complications may be associated with an increased risk of future major adverse cardiovascular events (such as death, re-infarction, and revascularization).The incidence of periprocedural myocardial injury varies according to the different definition and cardiac biomarker .For 4th UDMI criteria with hs-cTn, 78% to 85% patients who undergoing elective PCI may suffer from periprocedural myocardial injury.

Experimental and clinical evidence highlight the abnormalities of the coronary microcirculation is one of the causes of myocardial ischemia.Coronary microvascular disturbances (CMD) have been associated with early stages of atherosclerosis even prior to any angiographic evidence of epicardial coronary stenosis, as well as to other cardiac pathologies such as myocardial hypertrophy and heart failure.

In this study, we try to conduct a double blinded, randomized, placebo-controlled trial，the aim of our trial is: (1) to observe whether the prophylactically intracoronary administration of nicorandil and verapamil could reduce the occurrence of periprocedural myocardial injury and infarction in CAD patients undergoing elective PCI.;(2) to observe whether the prophylactically intracoronary administration of nicorandil and verapamil has protective effect on coronary microcirculation after elective PCI.

Simple randomization in a 1:1 ratio will be made in blocks of variable size according to a random numbers generated by Excel 2019 to divide the patients to treatment group (Nicorandil and verapamil) and control group (Saline). The primary end points are the incidence of periprocedural myocardial injury and 4a MI and the level of the IMR,secondary end points include levels of hs-cTnI, CK-MB ,NT-proBNP and hs-CRP before, and 24 hours following PCI, and major adverse cardiovascular events at day 30. SPSS 26.0 will be used, and P-value < .05 will be considered statistically signifificant.

Inclusion Criteria:

• 1.diagnosis of CHD with FFR<0.8;2.elective PCI;

Exclusion Criteria:

• Patients with AMI, lesion at the opening of the main coronary artery，kidney dysfunction, Liver dysfunction，blood coagulation disorder ,NYHA III-IV,Degree II-III atrioventricular block,and restenosis after PCI，CABG will be excluded.