Innovative Journal Innovative Journal of Medical and Health Science 2693-499X 1 2 2020 10 31 ST-segment elevation myocardial infarction mimic and Passing phenomenon or Yasser’s phenomenon with squaring sign; don’t hurry for an emergency management; A case report 1 Yasser Mohammed Hassanain Elsayed Critical Care Unit, Fraskour Central Hospital, Damietta Health Affairs, Egyptian Ministry of Health (MOH), Damietta, Egypt Journal Article Abstract Rationale: The ST-segment elevation myocardial infarction has been considered one of the most momentous cardiovascular disorders. Dynamic changes during an electrocardiographic registration are well-established alterations. There is wide-differentiation for ST-segment elevation. The new Passing phenomenon (Yasser’s phenomenon) is a group of fleeting electrocardiographic dynamic changes. These changes are extemporaneously reversed within a few seconds to a few minutes without any medical interventions. They were commonly reported initially as an abnormal diagnosis by cardiologists. The changes are unusual taking the opposite normal side. They may be passing as physiological or even transient changes. Patient concerns: A 48-year-old married, female, Egyptian teacher patient presented to the emergency department with palpitations and paroxysmal supraventricular tachycardia. Diagnosis: The ST-segment elevation myocardial infarction mimic and the Passing phenomenon (Yasser’s phenomenon) after paroxysmal supraventricular tachycardia. Interventions: Electrocardiogram, oxygenation, echocardiography, and verapamil intravenous injection. Outcomes: A spontaneously dramatic recovery of electrocardiographic changes without clinical impact. Lessons: Don’t hurry for the emergency management Passing phenomenon (Yasser’s phenomenon) which is associated with squaring sign until an accurate well-established evaluation. Differential diagnosis is very important. Reassurance and follow up is the keystone in the management. Vogel, B, Claessen, B E, Arnold, S V, ST-segment elevation myocardial infarction, 2019, https://doi.org/10.1038/s41572-019-0090-3 Vogel, B, Claessen, B E, Arnold, S V, ST-segment elevation myocardial infarction, 2019, https://doi.org/10.1038/s41572-019-0090-3 Wilson, P W, Established risk factors and coronary artery disease: the Framingham Study, Am J Hypertens, 1994, 7, 7 Akbar, H, Foth, C, Kahloon, R A, Mountfort, S, Acute ST Elevation Myocardial Infarction, 2020, https://www.ncbi.nlm.nih.gov/books/NBK532281/ Thygesen, K, Alpert, J S, Jaffe, A S, Simoons, M L, Chaitman, B R, White, H D, Joint ESC/ACCF/AHA/WHF Task Force for the Universal Definition of Myocardial Infarction, Circulation, 2012, 126, 16