Modify the trial design and construct a new larger trial.

The goal of this clinical trial is to to evaluate the effect of oral isosorbide mononitrate plus amlodipine antispasm therapy on outcomes of radial artery grafts in patients underwent primary isolated CABG.

The main question it aims to answer is:

Whether the oral isosorbide mononitrate plus amlodipine antispasm therapy could reduce the failure outcome of radial artery grafts after CABG .

Researchers will compare isosorbide mononitrate plus amlodipine to none to see if isosorbide mononitrate plus amlodipine works.

Participants will

1. Take oral isosorbide mononitrate (20-40mg daily) plus amlodipine (2.5-5mg daily) therapy for 24 weeks after CABG.
2. Clinical follow-up at Week 1, 4, 12, and 24 after CABG.
3. Protocol-driven CCTA at Week 24 after CABG.

Inclusion Criteria:

• Age≥18 years old，
• Any sex，
• Signed informed consent，
• Within 3 days after primary isolated CABG using RA graft

Exclusion Criteria:

1. Allergy to isosorbide mononitrate or amlodipine.
2. Hypotension (systolic BP <90 mmHg or diastolic BP <60 mmHg)
3. Acute myocardial infarction or cardiogenic shock
4. Contraindications for CCTA examination (eg., iodine allergy)