Can ischemic time predict the age of thrombus in ST elevation myocardial infarction?: an analysis from tertiary healthcare center in South India -

Background:  ST Elevation myocardial infarction (STEMI) is characterized by plaque disruption with superimposed thrombus formation. However, studies from western population have suggested a delay between plaque disruption and the onset of symptoms. There is a paucity of Indian data on the relationship between ischemic time and the age of thrombus. Hence, we decided to study the histopathological characteristics of thrombus aspirated during primary percutaneous coronary intervention (PPCI) in patients of STEMI and its relation with the ischemic time. Methods: 107 consecutive patients of STEMI undergoing PPCI with thrombus aspiration, mostly within 12 hours of symptom onset were included in this study. The aspirated thrombi were fixed in 10% formalin, processed and analysed by light microscopy. The thrombi were categorized as recent or lysed according to the histopathological characteristics. Results:  The mean age of the study population was 54.93 13.19 years. There were males 94 (87.85%) and 13(12.15%) were females. The culprit vessel was LAD in 36 (32.73%), RCA in 57 (51.82%) and LCX in 13 (11.82%). Left Main, Diagonal and OM were culprit vessels in one case (0.91%) each. Thrombus was identified in 102 (95.3%) out of 107 patients where as in five patients (4.7%) only plaque was seen. Histopathology revealed lysed thrombus in 68 (66.7%) of 102 patients, and recent thrombus in 34 (33.3%) patients. Conclusions:  In patients with STEMI, undergoing PPCI within 12 hours of symptom onset, majority of the thrombi were lysed indicative of a thrombus age of at least 24 hours. This suggests that plaque instability and thrombus formation frequently precedes the onset of symptoms. Hence, ischemic time cannot predict the age of thrombus in STEMI.