Wellens syndrome is an electrocardiogram (ECG) pattern seen in high-risk patients with unstable angina pectoris. It is characterized by inverted or biphasic T-waves that change into positive or pseudo-normalized waves at precordial leads when the patient experiences an angina attack; however, the mechanism for this condition remains unclear.A 47-year-old male patient experienced repeated, unprovoked episodes of chest pain for > 20 d, with worsening during the previous day. On the day of admission, he experienced episodes of paroxysmal chest pain lasting more than 30 min, in addition to radiating pain to the left arm and exertional dyspnea. The patient presented to the emergency department with no chest pain or other discomfort at that time. ECG at presentation showed sinus tachycardia and T-wave changes, which were identified as Wellens syndrome when combined with previous ECG findings. ECGs and myocardial enzymology examinations were normal when angina was present, but the ECG showed inverted or biphasic T-waves when angina was absent. After percutaneous coronary intervention, the ECGs demonstrated inverted or biphasic T-waves in the anterior precordial leads on days 0, 1, and 2, but normal T-waves on day 3. The ECGs showed no subsequent ischemic ST-T-wave changes.The Wellens syndrome pseudo-normalized T-waves likely reflect development of unstable angina pectoris into the hyperacute phase of ST-segment elevation myocardial infarction.©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.