The clinical benefits of percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) is still controversial. The purpose of this study is to assess the quantitative therapeutic benefits of successful PCI for CTO from the clinical data acquired by myocardial perfusion imaging (MPI). Consecutive 42 patients, who were successfully revascularized of CTO between August 2013 and March 2018, were examined. A stress MPI was performed before CTO PCI and at follow-up, and the changes in quantitative gated and perfusion single photon emission computed tomography parameters were examined. The follow-up interval was 18 ± 9 (median 14) months, during which 36 patients were maintained patency (patent CTO), while 6 were re-occluded (R/O CTO). The reduction in the % myocardial ischemia and the improvement in the ejection fraction were significantly higher in the patent CTO group than those in the R/O CTO group (67.5 ± 37.0% vs. − 56.4 ± 84.9%, p < 0.0001, 20.7 ± 49.8% vs. − 9.2 ± 20.6%, p = 0.0247, respectively). Interestingly, the improvements we observed were predominantly in the patients with LAD CTO rather than those with RCA or LCx CTO. Successful CTO PCI was able to reduce myocardial ischemia and improve the cardiac function when the patency after CTO PCI was maintained, with the most notable significance in the patients with LAD CTO.