Background In the TARGET I randomized controlled trial, the novel abluminal groove-filled biodegradable polymer sirolimus-eluting stent FIREHAWK proved non-inferior to the everolimus-eluting stent in nine-month in-stent late loss in single de novo coronary lesions. This study was aimed at evaluating clinical safety and effectiveness of FIREHAWK in a moderately complex population (including patients with small vessels, long lesions and multi-vessels), and at validating the ability of the SYNTAX score (SS) to predict clinical outcomes in patients treated with this latest generation drug-eluting stent. Methods TARGET II was a prospective, multicenter, single-arm study with primary outcome of 12-month target lesion failure (TLF), including cardiac death, target vessel myocardial infarction (TV-MI) and ischemia-driven target lesion revascularization (TLR). Stent thrombosis was defined according to the Academic Research Consortium (ARC) definition. Patients were grouped by tertiles of SS (<= 6, >6 to <= 12, and >12). All patients were exclusively treated with the FIREHAWK stent and were followed up at 1, 6, and 12 months, and annually thereafter up to five years. Results A total of 730 patients were included in this registry study. The 12-month incidence of TLF was 4.4% and the incidence of TLF components were, cardiac death 0.5%, TV-MI 3.2%, and TLR 2.2%. One definite/probable stent thrombosis was observed at 12-month follow-up. Mean SS was 10.87 +/- 6.87. Patients in the SS >12 tertile had significantly higher TLF (P=0.02) and TLR (P <0.01) rates than those in lower SS groups. In COX proportional-hazards regression analyses, TLF incidence was strongly related to lesion length (long lesion vs. non-long lesion patients; HR 3.416, 95% CI, 1.622-7.195), but unrelated to diabetic, small vessel, and multivessel subgroups. Conclusions The low TLF incidence in this study indicates that FIREHAWK is safe and effective in the treatment of moderately complex coronary disease. SS is also able to predict adverse clinical outcomes in FIREHAWK treated patients.