Background: Resolution of ST-segment (STR) and thrombolysis in myocardial infarction (TIMI) and frame count (TFC) are useful parameters to evaluate the reperfusion status following primary percutaneous coronary intervention (PPCI) in ST-elevation myocardial infarction (STEMI) patients. Objectives: Here, the association of ejection fraction (EF), as a parameter of systolic function, with TFC and STR was assessed in patients with STEMI who underwent PPCI. Methods: Ejection fraction was evaluated by transthoracic echocardiography using Simpson’s biplane method before PPCI in the first 24 hours after the admission of STEMI patients. Also, STR and TFC were assessed in all patients after PPCI. Then, the association of EF with STR and TFC was examined before and after the operation. Results: STEMI patients with STR less or greater than 50% were comparable in terms of clinical and demographic characteristics and laboratory indices. Our results showed a weak inverse correlation between EF before PPCI and TFC (r = -0.2336, P = 0.0002). However, there was a strong inverse correlation between EF after PPCI and TFC (P < 0.0001, r = -0.3137). The results of correlation analysis showed that the mean EF (pre- and post-PPCI) was significantly higher in patients with STR of ≥50% compared to those with STR < 50%. Conclusions: The results of this study showed that EF after PPCI, as an echocardiographic indicator, could reflect the status of cardiac and microvascular perfusion. We also found that cardiac status on ECG could better reflect EF.