ABSTRACT
<p><b>OBJECTIVE</b>To compare the differences on onset timing of acute ST segment elevation myocardial infarction (STEMI) in young and aged patients.</p><p><b>METHODS</b>The exact onset time of symptoms was obtained from 1024 consecutive patients with STEMI admitted to our hospital between January 2000 and May 2010. Patients were classified as the middle-aged group [< 65 years old, mean (52.2 ± 8.0) years, n = 536] and old group [≥ 65 years old, (72.2 ± 5.5) years, n = 488], the difference of the onset months, weeks, weekdays and hours between two groups was compared.</p><p><b>RESULTS</b>The high onset timing of STEMI in middle-aged group was October and February, Friday, Saturday and Wednesday, at 10 A.m. and 10 P.m. The high onset timing of STEMI in old group was October, January and March, Friday, Sunday and Monday, at 6 A.m. and 2 A.m. The incidences of STEMI in the old group were significant higher than in the middle-aged group in March (11.89%), on Sunday (15.97%) and Monday (17.42%), at 6 A.m. (6.35%) and 2 A.m. (5.74%) (all P < 0.05) while the onset rate was significant higher in February (9.89%), On Saturday (16.98%), At 8 P.m. (4.86%) and 10 P.m. (5.78%) in the middle-aged group than old group (all P < 0.05).</p><p><b>CONCLUSION</b>The onset timing of STEMI in old patients was significant different from the middle-aged patients suggesting the onset timing of STEMI changes with aging.</p>