Acute myocardial infarction without disrupted yellow plaque in young patients below 50 years old.

OBJECTIVE

Thrombosis caused by disrupted yellow plaque is regarded as a cause of acute myocardial infarction (MI). However, it has not been clarified if young patients have the same pathophysiology as older ones. Therefore, we elucidated clinical and angioscopic characteristics of young patients.

METHODS

Among a series of patients (n = 893) who received catheterization for acute MI, clinical characteristics were compared between patients <50 years (n = 66) and the rest of patients. Angioscopic appearance of culprit lesions was evaluated in 20 young patients in whom angioscopic examination was successfully performed. It was determined if culprit lesions had disrupted yellow plaque with thrombus (DYP&T).

RESULTS

Patients <50 years had higher prevalence of smoking (68% vs. 48%, P = 0.001), obesity (42% vs. 15%, P < 0.0001), and hypercholesterolemia (56% vs. 35%, P = 0.0005) than those >or=50 years. DYP&T was detected at culprit lesions in 14 (70%) patients. Prevalence of DYP&T was lower in patients <40 years (44% vs. 91%, P = 0.02) than those between 40 and 50 years. Patients <40 years had a trend for higher prevalence of smoking (88% vs. 62%, P = 0.05) than those between 40 and 50 years.

CONCLUSIONS

Patients with acute MI < 50 years, especially <40 years, had lower prevalence of DYP&T but higher prevalence of smoking, obesity, and hypercholesterolemia. Smoking may play an important role for thrombotic occlusion at lesions with relatively low thrombogenic potential.