Coronary artery disease (CAD) continues to be the foremost cause of cardiac mortality and morbidity, and causes a negative impact on the physical, psychological, social, and occupational functioning of patients. CAD affects around 126 million individuals (1,655 per 100,000), which is approximately 1.72% of the world’s population and around nine million deaths are caused by CAD globally. The global prevalence of CAD is rising. There are several factors associated with poor clinical outcomes in AMI, one important factor being chronic total occlusion (CTO) in non-infarct related artery (IRA). Coronary chronic total occlusions(CTOs) is defined as occluded coronary segment with thrombolysis in myocardial infarction (TIMI) flow 0 for ≥ 3 months duration. Approximately 18–33% of patients with significant coronary disease on coronary angiography have atleast one CTO.
Recent studies have shown that the predictive significance of Multi-vessel disease is primarily influenced by the existence of a chronic total occlusion (CTO) in a non-infarct-related artery (IRA). Chronic total occlusion (CTO) is associated with both cardiogenic shock upon admission and early mortality. The HORIZONS-AMI trial found that among patients with ST-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI), having multi-vessel disease (MVD) with a chronic total occlusion (CTO) in a non-infarct-related artery (IRA) is linked to worsened markers of reperfusion and higher mortality. In STEMI patients complicated by cardiogenic shock, CTO in non-IRA is associated with increased mortality.  A large retrospective study showed that the MACE, all-caused death and cardiac death is significantly higher in patients of CTO vs 90-99%  stenosis.

Presence of CTO in non-culprit artery is also associated with poor left ventricular ejection fraction (LVEF) and further deterioration of LVEF in follow-up. In patients of STEMI, a cardiac magnetic resonance study revealed that the existence of CTO increases myocardial injury and rates of major adverse cardiovascular events (MACE). In one trial, it had been showed that revascularisation for CTO with reduced EF would be associated with better prognosis than optimal medical therapy. Whereas the EXPLORE trial, which conducted a random assignment of STEMI patients with CTO into groups undergoing percutaneous coronary intervention (PCI) to CTO and those without PCI to CTO, did not observe a general advantage for PCI to CTO concerning left ventricular ejection fraction (LVEF) or left ventricular end-diastolic volume (LVEDV).  However, the success rate of PCI to CTO was not sufficiently high in this trial. However, these studies defined multi-vessel disease as lesions with a diameter stenosis of ≥50%. These studies included patients with single-vessel disease or intermediate stenosis as competitors to the CTO group.

Upto now most of the studies compared CTO to non-CTO and did not see the in-hospital outcome of non-culprit CTO to severe stenosis in non-IRA, therefore in this study we probe to see the in-hospital outcome of CTO vs severe stenosis in non-IRA to further prove the role of CTO itself  in patients of acute STEMI undergoing primary PCI