〔Abstract〕 Objective To investigate the improvement of 12-lead ecg indexes such as T-wave amplitude, Tpeak-Tend(Tp-Te) in patients with chronic coronary total occlusion(CTO) of single-branch before and after percutaneous coronary intervention(PCI), and to compare the improvement of cardiac function(NYHA) grading in six months of follow-up. Methods 192 consecutive patients with single vessel CTO who underwent PCI were divided into two groups according to with or without old myocardial: CTO group with old myocardial infarction(MI CTO group,106 cases) and CTO group without old myocardial infarction( non MI CTO group,86 cases). The repolarization indexes before and after revascularization and NYHA grading after six months were compared. Results Among the ecg indexes of the two groups,the preoperative T-wave amplitude of the inferior wall leads,and the TpTe indexes of the inferior wall leads and the anterior wall leads were significantly different( P<0. 05). There was statistically significant difference in Tp-Te of lead Ⅰ and Ⅲ after revascularization( P<0. 05). In the MI CTO group,both the T-wave amplitude and Tp-Te,indexs of postoperative repolarization,showed statistically significant difference compared with the preoperation( P<0. 05). After revascultation in the non-MI CTO group,there were statistically significant differences in Tp-Te of the seven leads( Ⅰlead,Ⅲ lead,AVR lead,AVF lead,V4 lead,V5 lead and V6 lead)( P<0. 05). Follow-up for 6 months showed no statistically significant difference in NYHA grading between the groups,but there was statistically significant difference in NYHA grading within the groups( P<0. 05). Conclusion Both repolarization index and cardiac function are improved after revascularization. CTO patients without old myocardial infarction are caused by Tp-Te improvement,while CTO patients with old myocardial infarction are caused by improvement of T wave amplitude and Tp-Te.