In 1970, the first percutaneous balloon coronary angioplasty opened a new chapter of interventional therapy. However, the incidence of intracoronary restenosis was about 30%. Subsequently, bare metal stents and drug-eluting stents (DES) reduced the incidence of in-stent restenosis (ISR) to 5%-10% and it was still a bottleneck treated by percutaneous coronary intervention (PCI). Currently, ISR is mainly treated by balloon angioplasty, stent implantation and coronary artery bypass grafting.

In 2014, the guidelines of the European Society of Cardiology recommended that drug balloon therapy (DCB) and new generation DES should be the preferred strategies for ISR treatment. Compared with DES, DCB treatment can avoid the inflammation of intima caused by multi-layer stent strut, and reduce the risk of intimal hyperplasia and thrombosis in stent. However, DCB lacks sustained radial support. Even if the residual stenosis is less than 30% after sufficient pre-dilation, the elastic retraction of the intima still exists. In addition, the antiproliferative effect of paclitaxel is significantly worse than that of sirolimus and its derivatives, and there is a lack of long-term sustained release of anti-proliferative drugs. Compared with DCB, DES can obtain long-term stable radial support and long-term anti-proliferation effect, but stent struts exposed in the vascular lumen are at risk of stent thrombosis. The new generation of DES improves the design of stent platform, improves the polymer coating, and applies new anti-proliferative drugs. It effectively reduces the inflammation of vascular wall, speeds up the process of vascular re-endothelialization, promotes early vascular repair, and significantly reduces the incidence of stent thrombosis. Recent BIOLUXRCT, RESTORE and DARE studies provide more powerful evidence for the treatment of ISR by new generation DES.

Quantitative flow ratio (QFR) is the second generation FFR detectional method based on coronary contrast image. The latest FAVOR II results also confirm that QFR is more sensitive and specific than quantitative coronary analysis (QCA) in the diagnosis of myocardial ischemia caused by coronary artery stenosis. However, there is no report of ISR treated with DCB under the guidance of QFR. The aim of this study was to evaluate the safety and efficacy of DCB in the treatment of in-stent restenosis in patients with coronary heart disease (CHD) under the guidance of QFR compared with DES implantation.

The current study is designed as a multicenter, randomized and prospective study aiming to evaluate the safety and efficacy of drug balloon therapy for ISR in patients with CHD under the guidance of QFR compared with DES implantation. Based on previous study reported, the incidence rate of target lesion failure is about 3% in patients with ISR undergoing DES implantation. And the design of non-inferiority study was performed in our study. Moreover, the investigators estimated 10% loss follow-up of these patients in each arm. As a result, a total of 220 patients with ISR were required, and with 110 patients per group as a ratio of 1:1 randomization.

Inclusion Criteria:

● Meet the diagnostic criteria for patients with coronary in-stent restenosis and QFR<0.8 of target lesion in the coronary stent

Exclusion Criteria:

• QFR less than 0.8, dissection above type B and thrombosis formation after pre-dilation of ISR
• Severe congestive heart failure [LVEF <30% or NYHA( New York Heart Association) III/IV)]
• Severe valvular heart disease
• Life expectancy no more than 1 year or factors causing difficulties in clinical follow up
• Intolerance to aspirin and/or clopidogrel
• Known intolerance or allergy to heparin, contrast agents, paclitaxel, iopromide, rapamycin, polylactic acid-glycolic acid copolymer, Co-Cr alloy or platinum-chromium alloy
• Leukopenia or thrombopenia
• A history of peptic ulcer or GI bleeding in the previously
• Stroke within 6 months prior to the operation
• A history of severe hepatic or renal failure