The activated partial thromboplastin time in early diagnosis of myocardialinfarction

Intracoronary thrombosis is fundamental to the pathogenesis of acute myocar dial infarction (MI), yet few studies have examined the diagnostic value of routine coagulability markers, such as the activated partial thromboplasti n time (aPTT), in patients with chest pain. We hypothesized that the initia tion of thrombosis early in MI would shorten the aPTT, and conducted a retr ospective cohort study of patients admitted with a diagnosis of chest pain through the emergency department of one community hospital between 1 Januar y and 30 August 1998. Patients were diagnosed as MI positive or negative ba sed on World Health Organization (WHO) criteria. The aPTT obtained on arriv al (prior to anticoagulation therapy) was retrieved from the electronic med ical record. Of 120 eligible patients (49% female, mean age 63.7 years), 27 (23%) were diagnosed with MI. Patients with an aPTT less than or equal to control (n=73, 61%) were significantly more likely to be diagnosed with MI than those with an aPTT > control (RR=2.83, 95% confidence interval 1.15 to 6.96, P=0.013). A shortened aPTT (control) on presentation in patients wit h chest pain is associated with increased risk of acute MI. This informatio n is available before other serum markers of MI, and may facilitate early t reatment decisions. Further study is warranted. (C) 2001 Lippincott William s & Wilkins.