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Background Coronary vascular function of a chronic coronary total occlusion (CTO) immediately after recanalization is known to be poor and to be partially improved by pre-treatment with loading dose of ticagrelor vs. clopidogrel . It is unknown if this vascular dysfunction is maintained at long-term follow-up and may be improved by 1-year dual antiplatelet therapy (DAPT). Methods The TIGER is a prospective, open-label, two parallel-group controlled clinical trial , which 1:1 randomized 50 CTO patients to pre-PCI loading dose and subsequent 1-year DAPT with ticagrelor vs. clopidogrel. Coronary blood flow (CBF) under stepwise adenosine infusion was assessed after drug loading dose and at follow-up and compared between the two drug groups, adjusting for time of follow-up. Results Out of 50 patients with index CBF evaluation, 38 (76%) patients underwent angiographic follow-up (23 and 15 at 1 and 3-year, respectively) and Doppler data was available in 35 (70%). A high CBF area under the curve (AUC), already observed after loading dose in ticagrelor vs. clopidogrel group (p = 0.027), was maintained at follow-up (AUC 34815.22 ± 24,206.06 vs. AUC 22712.47 ± 13,768.95; p = 0.071). Specifically, whereas high ticagrelor loading dose-related CBF was sustained at follow-up (p = 0.933), clopidogrel loading dose-related CBF increased at follow-up (p = 0.039). Conclusion The TIGER trial showed that DAPT with ticagrelor maintained a non-significantly higher CBF in a recanalized CTO as compared to clopidogrel, whose treated patients exhibit a lower CBF immediately after PCI with a significant increase at follow-up. The clinical value of such sustained high coronary flow should be evaluated in a larger group of patients. Clinical trial registration https://clinicaltrials.gov/ct2/show/NCT02211066 (ClinicalTrials.gov number NCT02211066 ).