Assess the Efficacy and Safety of RESTORE Paclitaxel Eluting Balloon Versus RESOLUTE Zotarolimus Eluting Stent for the Treatment of Small Coronary Vessel Disease

Inclusion Criteria: Related to the patients: 1. Age ≥18 years old 2. Patients with stable or unstable angina pectoris, or recent myocardial infarction which has been stabilized (occurred over 7 days before enrollment, including non-st segment elevation myocardial infarction(NSTMI) and STMI), or proved asymptomatic regional myocardial ischemia 3. Patients in the small vessel cohort should be suitable for balloon dilation angioplasty or stent implantation, patients in the very small vessel cohort should be suitable for balloon dilation angioplasty. 4. Patients should have sufficient compliance and agree to receive follow-ups in month-1, 6, 9 and 12, and follow-up visit in year-2, 3, 4, and 5. It is required to perform angiography in month-9. 5. Patients should volunteer to participate in this study, and sign the written informed consent form, and understand all risks and benefits in the informed consent document. Related to the diseases: 6. Patients with de novo, in situ lesions of small coronary vessels, the length of the lesion should be ≤26mm according to visual inspection. In the small vessel cohort, the diameter of the target lesion should be ≥2.25mm and ≤2.75mm according to visual inspection, and in the very small vessel cohort, the diameter of the target lesion should be ≥2. 00mm and \<2.25mm according to visual inspection. 7. The diameter stenosis according to visual inspection before intervention treatment should be ≥70% or ≥50% with the evidence of ischemia. 8. Each patient is allowed to have only one lesion of the target small vessel (2 lesions with the distance ≤10mm and total length ≤26mm which could be treated with the same balloon or stent is considered as one lesion). Exclusion Criteria: Related to the patients: 1. Myocardial infarction occurred within 1 week before enrollment. 2. Patients with severe congestive heart failure or New York Heart Association (NYHA) grade IV heart failure 3. Left ventricular ejection fraction (LVEF) \<35% 4. Patients who had heart transplantation 5. Patients with severe valvular heart disease 6. The patients had cerebral stroke within 6 months before being included, or have a history of peptic ulcer or gastrointestinal bleeding in the past 6 months, or the patients have a bleeding tendency according to the investigator. 7. Patients with a history of leukopenia (white blood cell count \<3×109/L for more than 3 days) or neutropenia (ANC\<1000/mm3 for more than 3 days) or thrombocytopenia (platelet \<100,000/mm3) 8. Patients with renal insufficiency (eGFR\<30ml/min) 9. Patients who are forbidden to use anticoagulation agents or anti-platelet drugs, and unable to tolerate Aspirin or Clopidogrel 10. Patients who are known to be allergic to Paclitaxel or Zotarolimus 11. The patients have a life expectancy of less than 1 year, or it would be difficult to finish follow-ups within 1 year. 12. Pregnant or lactating women, or female patients at a child-bearing age who plan to get pregnant during the period of the study or could not take effective contraceptives 13. The patients are participating in any clinical trials of other drugs or devices before reaching the primary endpoints. 14. Patients who are unsuitable for the study according to the investigator due to other reasons Related to the diseases: 15. Patients with total occlusion of the target vessel 16. The patients have severe calcification of the target lesion, and therefore balloon pre-dilation could not be performed successfully. 17. The target lesions are bifurcation lesion with the diameter of the branch vessel \>2.00mm. 18. The target lesions are in-stent restenosis. 19. Angiography indicates thrombosis in the target vessel. 20. Complicated with lesions in left main(LM) requiring intervention treatment 21. There are more than 2 non-target lesions which require treatment, or could not be treated with intervention before the target lesion, or the treatment had failed.