Background: Acute myocardial infarction is a major problem of public healthcare in Thailand. In the emergency room, patients who present chest pain are at low risk for myocardial infarction and short term risk of adverse cardiac events. In the present study, the incidence of major adverse cardiac events among low risk chest pain patients who presented at the emergency room of Rajavithi Hospital was investigated to improve treatment in the future.
Objective: To evaluate incidence of major adverse cardiac events within 30 days among patients with low risk chest pain for myocardial infarction admitted to the emergency room at Rajavithi Hospital.
Material and Method: This prospective observational study was undertaken at emergency the room of Rajavithi Hospital. Low risk chest pain patients, classified by normal ECG, normal Troponin T level and Thrombolysis in Myocardial Infarction (TIMI) score less than 2, suspected of acute myocardial infarction, were included from October 1, 2012 to October 31, 2013. Primary endpoint was major adverse cardiac event (MACE) within 30 days after initial presentation.
Results: In all, 209 patients were enrolled in this study comprising females, 51.7% and mean age 54.84+16.44 years. A total of 84 patients had TIMI score 1 (40.2%), 67 patients had TIMI score 2 (32.1%) and 58 patients had TIMI score 0 (27.7%). At 30 days after presenting, two patients had a major adverse cardiac event (0.9%), both of them had TIMI score 2. No significant difference was observed between TIMI score 2 and other groups of TIMI score for major adverse cardiac adverse event (p-value = 0.075). The most common of TIMI risk factor was chest pain >2 episodes within 24 hours (86 patients, 41.2%). The most common underlying disease or previous history was congestive heart failure (33 patients 15.8%) but no factors had statistical significance for major adverse cardiac events among low risk chest pain patients.
Conclusion: Incidence of a major adverse cardiac event within 30 days among low risk chest pain patients was low. No significant difference was observed between each group of TIMI score 0-2 for major adverse cardiac event and no significant risk factor was found for major adverse cardiac events in low risk chest pain patients.

Keywords: Thrombolysis in myocardial infarction score (TIMI score), Major adverse cardiac event (MACE), Electrocardiography (ECG)