lthough young adults are a relatively small proportion of those having acute myocardial infarction (AMI), they are an important group to examine with regard to risk factor modification and secondary prevention. Previous studies have indicated that patients less than 40 years old comprise between 2% and 6% of all AMIs 1-3 and that AMI in young patients has different characteristics from that in older patients. Young AMI patients are characterized by a relatively high incidence of normal coronary arteries, non-obstructive stenosis, or single-vessel disease, 1,4,5 and high prevalence of current smoking, hyperlipidemia, and family history. 6,7 In addition, non-classical risk factors, such as vasospastic tendency, thrombophilic conditions, and past history of Kawasaki disease, have also been proposed as the cause of AMI in young patients. [8][9][10][11][12] Recently we demonstrated that young Japanese patients with AMI are usually male and have a high prevalence of cigarette smoking, hypercholesterolemia, and family history, a higher frequency of single-vessel disease, and a lower frequency of left circumflex coronary artery as the culprit lesion. 13 As to the short-and long-term prognosis, most previous reports have shown a favorable prognosis after discharge in young AMI patients, 1,14,15 and we have already shown that initial results of primary percutaneous coronary intervention (PCI) and in-hospital outcome in young patients with AMI are comparable to those in non-young patients with AMI in Japan. 13 However, the data on the medium-and long-term prognosis of young Japanese patients with AMI, aged <40 years, are still lacking. The AMI-Kyoto MultiCenter Risk Study, a large multicenter observational study in which 15 collaborating hospitals in Kyoto Prefecture have collected demographic, procedural, and outcome data on AMI patients, was established in 2000 in order to analyze these data and establish an emergency-hospital network for heart disease in Kyoto. The purpose of the present study is therefore to examine retrospectively the medium-term outcome in young adults with AMI in Japan.
Methods
Patient PopulationFrom January 2000 to Background Data on the medium-and long-term prognosis of young Japanese patients with acute myocardial infarction (AMI) are still lacking.
Methods and ResultsIn the present study, 1,458 AMI patients were enrolled in the AMI-Kyoto Multi-Center Risk Study between January 2000 and December 2003. Of these, clinical characteristics and medium-term prognosis were retrospectively compared in 21 young patients <40 years (young group), and 190 non-young patients 60-70 years old (non-young group) who could be followed after hospital discharge. The young group was all male and had higher prevalence of current smoking and greater body mass index, but previous myocardial infarction (MI) and hypertension were more prevalent in the non-young group. The young group had a higher prevalence of single-vessel disease and a lesser incidence of left circumflex coronary artery as the culprit lesion. The acquis...