Background: Elevated heart rate (HR) is associated with cardiovascular mortality and other events associated with acute myocardial infarction (AMI). The heart rate after discharge is likely superior to reflect the deteriorating heart function, which negatively responds to normal physical activity. This study aimed to explore the effect of HR at the first outpatient visit on clinical outcomes. Methods: We retrospectively identified 605 patients with AMI. HRs at admission, discharge, and first outpatient visits were measured. The primary endpoint was defined as major adverse cardiovascular events (MACEs), including cardiovascular (CV) death, readmission for worsening heart failure, recurrent nonfatal myocardial infarction (MI), repeated coronary revascularization, and ischemic stroke. Results: During the follow-up period, 145 cases of MACE occurred, including 34 CV deaths, 31 recurrent MI, 89 revascularizations, 41 heart failures, and 4 strokes. The event group displayed an elevated HR at the first outpatient visit compared to the event-free group (p 0.001). After adjustment for confounding risk factors, Cox models showed that the outpatient HR had the best correlation with MACE [Hazard ratio (HR) = 1.33, 95% confidence interval (CI) = 10.8–59.3, p 0.01 for increments of 1 standard deviation (SD) in the outpatient HR) and CV mortality (HR = 1.18, 95% CI = 1.052–1.325, p 0.01) compared with the other two HRs. The restricted spline model indicated that HR at the first post-discharge above 71 bpm was associated with CV mortality. Conclusions: Elevated HR at the first outpatient visit over a period of 2–4 weeks is related to the adverse outcomes of AMI and may identify AMI patients at higher risk of CV mortality.