Clinical Characteristics and Outcomes in Young Patients With ST-Segment Elevation Myocardial Infarction After Primary Percutaneous Coronary Intervention.

Background: There are few published studies of ST-segment elevation myocardial infarction (STEMI) in younger individuals. The differences between these "younger" and "older" individuals may not be fully appreciated by clinicians. The aim of this study was to determine the reasons for the earlier presentation and help to identify strategies for prevention of recurrent myocardial infarction (MI) in younger patients. Methods: The study population was a cohort of 2,419 consecutive STEMI patients who were treated with primary percutaneous coronary intervention. The median follow-up time of this retrospective study was 2.2 years. Results: The all-cause mortality rates in patients <= 45 years of age at 30 days, 1 and 2 years were 1.7%, 2.0% and 2.2%, respectively. These rates were lower compared with their older matched counterparts whose all-cause mortality rates were 3.3%, 4.2% and 5.5%, respectively (P = 0.010). The incidence of recurrent MI was 4.0% for all age groups combined, 5.4% for younger patients and 3.8% for older patients. The number of stents showed association with recurrent MI in older patients with a first infarction, whereas only composition factor 1 with significantly higher non high-density lipoprotein and low-density lipoprotein values was significantly associated with recurrent MI in the younger patients. Conclusions: STEMI patients <= 45 years of age more often had lower rates of all-cause mortality, but the risk of recurrent MI was similar to that of older patients. Regardless of triglyceride level, neither non high-density lipoprotein nor low-density lipoprotein were independent predictors for recurrent MI during the long-term follow-up in younger patients.