Background/Aims: Pulmonary hypertension (PH) in patients with heart failure contributes to a poor prognosis. However, the role of PH in the long-term clinical outcome is unclear in those with acute myocardial infarction (AMI). The clinical significance of elevated right ventricular systolic pressure (RVSP) on routine echocardiography is underestimated. Methods: This study enrolled 2,526 AMI patients (65.1 ± 12.7 years; 1,757 males [69.6%]) from the Korean AMI registry who underwent successful percutaneous coronary intervention and pre-discharge transthoracic echocardiography (TTE). The patients were divided into four groups according to the RVSP on TTE: normal RVSP (RVSP < 35 mmHg, n = 1,695), mild PH (35 ≤ RVSP < 45 mmHg, n = 601), moderate PH (45 ≤ RVSP < 70 mmHg, n = 211), and severe PH (RVSP ≥ 70 mmHg, n = 19). Major adverse cardiac events (MACE) were compared among the four groups. Results: During the 3-year clinical follow-up period, MACE occurred in 562 patients (22.2%), including 321 (18.9%), 145 (24.1%), 83 (39.3%), and 13 patients (68.4%) in the normal RVSP and mild, moderate, and severe PH groups, respectively. On multivariate analysis, independent factors for MACE were moderate or severe PH, age ≥ 65 years, Killip class ≥ III, left ventricular ejection frac...