Myocardial Injury Non-Related Atherosclerotic Plaque Disruption in Patients Younger than 40 Years Old

Backround: Myocardial infarction with coronary artery disease (MICAD) is the leading cause of myocardial injury. Myocardial injury non-related to atherosclerotic plaque disruption (non-MICAD) is a rare and heterogeneous diagnosis. Although MICAD is well studied, non-MICAD was not thoroughly identified in young patient population. We aimed to investigate the frequency, main etiologies, and five-year mortality of patients with non-MICAD younger than 40 years.

Methods: We retrospectively enrolled 292 patients with acute myocardial injury younger than 40 years between January 2010 and December 2014. Clinical, demographic, laboratory, angiographic features, and five-year all-cause mortality were compared between patients with non-MICAD (n=78) and MICAD (n=214).

Results: Median age of patients was 36. Non-MICAD group was younger than MICAD group [32 (28-37) vs 37 (34-39)]. The frequency of female patients with non-MICAD was higher than those with MICAD (24.4% vs 10.3%). Most of the patients with MICAD presented with STEMI (77.1%), while most of the patients with non-MICAD presented with non-STEMI (89.7%). Most common etiologies of non-MICAD in were myocarditis (32%) and vasospasm (9%). Age, female sex, no smoking and, absence of dyslipidemia were independent predictors for non-MICAD. Five-year all-cause mortality in non-MICAD group was significantly lower than MICAD group (2.6% vs 10.3%) (log-rank test p=0.04).

Conclusion: Non-MICAD represents a heterogeneous group of patients who had varying etiologies at different ages. Despite the lower mortality rate of non-MICAD group, different diagnostic and treatment strategies are required for management of patients with non-MICAD.