Background:Acute coronary syndrome (ACS) can be divided into subgroups of ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI), and unstable angina. ACS carries significant morbidity and mortality and prompt diagnosis.Thrombus encountered in the setting of acute coronary syndromes has been correlated with acute complications during the percutaneous coronary intervention (PCI) such as no-reflow, acute coronary occlusion, and long-term complicationsthat occurs later such as stent thrombus. Aim:To identify the electrocardiographic changes and the possible complications associated with thrombus formation in patients with Non-ST Segment Elevation Myocardial Infarction Methods:In this sample, 66 patients were enrolled in 2 groups; Group I (n = 33) represented the low level of thrombus; Group II (n = 33) represented the high level of thrombus. The degree of stenosis and coronary flux by thrombolysis in myocardial infarction (TIMI), grade, was assessed in all patients to assess the associated high thrombus plaque disruption or formation. Results:Class I and II have a mean age respectively 62.21±9.51 and a mean age of 66.67±9.14. The global systolic average LV (AGS) in Group I and II relative to Group III was slightly lower. Regarding the Killip class, the main difference between the groups was statistically significantwith a P-value of 0.001, regarding ECG Changes (ST depression and t wave inversion), the main difference between the groups was statistically non-significant with p values 0.726 and 0.403 respectively. ConclusionThe quantity of the intracoronary thrombus burden is associated with a poor prognosis in patients with the acute coronary syndrome.intracoronary thrombus plaque disruption occurs as a complication in non-ST segment elevation myocardial infarction patients undergoing primary PCI.