Differential Culprit Plaque Morphology in Acute Coronary Syndrome: A Comparison Between Very Young Patients (<=35 Years) and Older Counterparts Using Optical Coherence Tomography

Abstract

Abstract Background Underlying mechanisms responsible for acute coronary syndrome (ACS) in young patients compared to older counterparts are yet to be explored with optical coherence tomography (OCT). Objective To explore underlying mechanisms of ACS in ≤35 (very young) and >35-year-old (older counterparts) ACS patients using OCT. Methods This was a prospective, single-center, investigational study. Patients were divided into groups according to age (≤35 and >35 years) and further subdivided according to the underlying mechanism i.e. plaque rupture (PR) and plaque erosion (PE). Results A total of 93 patients were analyzed. Thin cap fibroatheroma (TCFA) was significantly higher among older counterparts than very young patients for both PR (80.0% vs. 31.8%, p=0.002) and PE (66.7% vs. 6.3%, p<0.001) groups. Micro-channels were also significantly more prevalent among older than very young patients for both PR (65.0% vs. 18.2%, p=0.004) and PE groups (55.6% vs.12.5%, p=0.013). Macrophages were significantly higher in older than very young patients for both PR (25.0% vs. 0%, p=0.018) and PE (44.4% vs. 0%, p=0.003) groups. In contrast, fibrous cap thickness was greater in very young than older patients for both PR (105.71±48.02 µm vs. 58.00±15.76 µm, p<0.001) and PE (126.67±48.22 µm vs. 54.38±24.21 µm, p<0.001) groups. Intimal thickness was greater in older than very young patients for both PR (728.00±313.92 µm vs. 342.27±142.02 µm, p<0.001) and PE (672.78±334.57 µm vs. 295.00±99.60 µm, p<0.001) groups. Conclusion Frequency of TCFA, micro-channels, macrophages, and intimal thickness was significantly higher in older ACS patients compared to very young patients. However, fibrous cap thickness was significantly greater in very young ACS patients compared to older patients.