Clinical Profile, Angiographic Findings, and Outcome of Isolated High Lateral ST-Elevation Myocardial Infarction; A Gender-Specific Longitudinal Study of A Rare Subtype of Myocardial Infarction
Authors: Mirhosseini Seyed Alireza , Azami Pouria , Hosseini Mehrasa , Akbari Mohammadreza , Khorshidi Soorena , Sadeghi Fatemeh , Pakmehr SeyedAbbas , Amanollahi Foad , Attar Armin 
Published: September 2024

Background
Isolated high lateral ST-Elevation Myocardial Infarction (STEMI) is a rare and insufficiently researched subtype of acute myocardial infarction, typically caused by atherosclerotic plaque formation and thrombosis in the diagonal and obtuse marginal branches of the coronary arteries. Although infrequent, it is essential to comprehend the clinical characteristics, angiographic findings, treatment approaches, and outcomes associated with this condition, particularly in the context of gender differences, to enhance patient care and outcomes.
Methods
This longitudinal study focused on patients diagnosed with isolated high lateral STEMI at a tertiary heart center. Diagnosis was based on electrocardiographic criteria, specifically ST-segment elevation of ≥ 0.1 mV in leads I and/or aVL, without corresponding ST-segment elevation in limb leads or ≥ 0.2 mV ST-elevation in precordial leads (except V5 or V6). The study collected data on patient demographics, comorbidities, angiographic findings, and treatment outcomes, with a median follow-up period of 32 months to evaluate major adverse cardiovascular events (MACE). Predictors of MACE within the study population were analyzed using Cox proportional hazards regression.
Results
Out of 7,944 STEMI patients screened over four years, 102 (1.28%) patients were diagnosed with isolated high lateral STEMI. The mean age was 55.42 years, with 67.65% of patients being male. Common comorbidities included hypertension (51.96%), diabetes mellitus (31.4%), and dyslipidemia (28.43%). Female patients often presented with diabetes mellitus, anemia, elevated platelet counts, and reduced estimated glomerular filtration rate (eGFR). In contrast, male patients, who generally exhibited more stable conditions at admission, had higher rates of previous coronary artery disease, smoking, and opium use. The diagonal artery was the most frequently identified culprit artery (37.25%), followed by the left anterior descending artery (12.74%) and obtuse marginal arteries (8.82%). Among patients for whom angiography did not detect an infarct-related artery, 38.46% had advanced three-vessel disease (A3VD), and 61.54% experienced MI without obvious coronary artery obstruction. MACE was observed in 26 patients during the total follow-up period, comprising 18 males and 8 females. Multivariable Cox regression analysis adjusted for age indicated that A3VD was associated with a fourfold increased risk of MACE (Hazard Ratio (HR): 4.08, p: 0.002). Excluding A3VD patients, who were predominantly females, the development of MACE was significantly associated with the left anterior descending artery (LAD) as the infarct-related artery (HR: 4.33, p: 0.019), presence of diabetes mellitus (HR: 4.28, p: 0.005), eGFR (HR: 0.65, p: 0.001), and male gender (HR: 9.91, p: 0.001). These findings suggest that although males have higher overall rates of MACE, females are more prone to experiencing the more severe, life-threatening aspects of MACE in this subtype of STEMI.
Conclusion
Isolated high lateral STEMI is a relatively uncommon but clinically important subset of STEMI, exhibiting distinct gender-related differences in both presentation and outcomes. Significant predictors of MACE include A3VD, LAD as infarct-related artery, diabetes mellitus, low GFR, and male gender. Interestingly, A3VD and LAD as infarct-related artery were more commonly observed in females, who also experienced more severe components of MACE. These findings emphasize the need for targeted management strategies tailored to this specific patient group.