Background Prior studies have demonstrated that the achievement of faster coronary artery flow following reperfusion therapies is associated with improved outcomes among ST-elevation myocardial infarction (STEMI) patients. The association of patient age with angiographic characteristics of flow and perfusion after rescue/adjunctive percutaneous coronary intervention (PCI) following the administration of fibrinolytic therapy has not been previously investigated. Objectives and Methods We examined the association between age (≥ 70 years or ＜ 70years)and clinical and angiographic outcomes in 1472 STEMI patients who underwent rescue/adjunctive PCI following fibrinolytic therapy in 7 TIMI trials. We hypothesized that elderly patients would have slower post-PCI epicardial flow and worsened outcomes compared to younger patients. Results The 218 patients aged ≥ 70 years (14.8%) had more comorbidities than younger patients. Although these patients had significant angiographic improvement in TIMI frame counts and rates of TIMI Grade 3 flow following rescue/adjunctive PCI, elderly patients had higher (slower)post-PCI TIMI frame counts compared to the younger cohort (25 vs 22 frames, P = 0.039), and less often achieved post-PCI TIMI Grade 3 flow (80.1 vs 86.4%, P = 0.017). The association between age ( ≥70 years) and slower post-PCI flow was independent of gender, time to treatment, left anterior descending (LAD) lesion location, and pulse and blood pressure on admission. Elderly patients also had 4-fold higher mortality at 30 days (12.0 vs 2.7%,P = 0. 001 ). Conclusions This study suggests one possible mechanism underlying worsened outcomes among elderly STEMI patients insofar as advanced chronological age was associated with higher TIMI frame counts and less frequent TIMI Grade 3 flow after rescue/adjunctive PCI.