Backgrounds Assessment of left ventricular filling pressure (LVFP) is of clinical importance in patients with ST elevation myocardial infarction (STEMI). Although several echocardiographic parameters are recommended for the assessment of LVFP, validation of these parameters in patients with STEMI is missing. We aimed to investigate the clinical utility of these parameters in acute settings. Methods: We prospectively included consecutive patients with STEMI. LV end-diastolic pressure (LVEDP) was measured following primary PCI and echocardiographic examination was performed within 24 hours. Mean left atrial pressure (mLAP) was calculated both invasively using Yamamoto's formula and non-invasively using Naugeh's formula. Mean LAP was considered increased when exceeded 18 mmHg. Results: Patients were grouped according to LVEDP, group 1(41 patients) and group 2(114 patients).There was no significant difference between groups in terms of comorbidities. NT pro-BNP levels (p < 0.001) and peak level of Hs-TnT (p-value: 0.002) were significantly higher in group 2. Average E/e ' ratio was significantly higher in group 2 (10.19 +/- 3.15 vs. 12.04 +/- 4.83, p: 0.046). Isovolumetric relaxation time was longer in group 2 (p < 0.001) and left atrial volume index (LAVI) was also significantly higher in group 2 (p < 0.001). Regression analyses revealed that septal, lateral and average E/e ' ratio, tricuspid regurgitation velocity, LAVI and left ventricular volume are correlated with mLAP. Among group 2 patients only 14 Patients fulfilled the increased LVFP criteria suggested by current guidelines. Conclusions Echocardiographic parameters indicating increased LVFP require validation and may need to be modified in patients with STEMI. Moreover, current algorithms underestimate the actual number of patients with increased LVFP.