To investigate the relationship between the TyG index, coronary lesion complexity assessed by the SYNTAX score, and the development of the no-reflow phenomenon in STEMI patients with T2DM.

Successful restoration of epicardial coronary artery patency in acute myocardial infarction (AMI) does not always guarantee adequate myocardial tissue perfusion or effective salvage of ischemic myocardium. In a substantial proportion of patients, microvascular dysfunction persists despite successful recanalization after percutaneous coronary intervention (PCI), limiting the expected clinical benefit of reperfusion therapy. This condition, known as the no-reflow phenomenon, is characterized by inadequate myocardial perfusion in the absence of angiographic evidence of mechanical vessel obstruction. No-reflow occurs in 2-60% of patients with ST-segment elevation myocardial infarction (STEMI) and is strongly associated with adverse ventricular remodeling, malignant arrhythmias, heart failure, and increased short- and long-term mortality.

Distal embolization of thrombus and plaque debris during PCI is a major mechanism underlying microvascular obstruction and no-reflow, emphasizing the importance of identifying high-risk coronary lesions before intervention. The SYNTAX score, an angiographic tool reflecting coronary lesion complexity, has been shown to predict clinical outcomes and the occurrence of no-reflow in patients undergoing PCI. Patients with type 2 diabetes mellitus (T2DM) represent a particularly vulnerable group, as they frequently exhibit more complex coronary lesions and a higher incidence of no-reflow.

Insulin resistance (IR) plays a central role in endothelial dysfunction, vascular inflammation, and atherothrombosis. The triglyceride-glucose (TyG) index, a simple and reliable surrogate of IR, has been associated with adverse cardiovascular outcomes and has recently been shown to predict the occurrence of no-reflow in STEMI patients with T2DM undergoing PCI.

Inclusion Criteria:

1. Age ≥ 18 years
2. Type 2 Diabetes Mellitus patients .
3. Undergoing PCI for STEMI.
4. Written informed consent obtained.

Exclusion Criteria:

• 1. Individuals with a previous history of myocardial infarction (MI) or decompensated heart failure.

  2. Individuals with Cardiogenic shock. 3. Individuals with a history of PCI or coronary artery bypass grafting (CABG). 4.Previous familial mixed dyslipidemia / Hypertriglycerideemia (Homozygous or heterozygous).

  5.Patients with significant hepatic impairment (transaminase levels ≥ 2x normal value).

  6.Patients with renal impairment (GFR < 60 mL/min/1.73 m²). 7.Active infection or inflammatory disease. 8.Known autoimmune disease. 9.Malignancy. 10. Type 1 Diabetes Mellitus patients.

Clinical, Laboratory, Insulin Resistance, and Angiographic Assessment Eligible patients with type 2 diabetes mellitus presenting with STEMI and undergoing primary PCI were prospectively evaluated. Clinical data included age, sex, BMI, cardiovascular risk factors, diabetes duration, ischemic time, Killip class, and infarct location. Laboratory investigations included fasting plasma glucose, HbA1c, lipid profile, CBC, serum creatinine, cardiac biomarkers, and hs-CRP. Insulin resistance was assessed using the triglyceride-glucose (TyG) index: ln [fasting triglycerides × fasting plasma glucose ÷ 2]. Coronary angiography assessed the infarct-related artery, TIMI flow, thrombus grade, lesion characteristics, and SYNTAX score. The primary endpoint was the occurrence of the no-reflow phenomenon after primary PCI.