FPIN's Help Desk Answers
Predictors of Acute Myocardial Infarction
Am Fam Physician. 2017 Sep 1;96(5):328.
What elements of a patient's chest pain history are the best predictors for ruling in/out acute myocardial infarction (MI)?
The most useful element for ruling in acute MI is chest pain with radiation to both arms, followed by radiation to the right arm. The most useful elements for ruling out acute MI are pleuritic chest pain, sharp pain, and pain reproduced by palpation. (Strength of Recommendation = A, based on two systematic reviews and one cohort study.)
A systematic review of 64 published studies and one unpublished study (N not reported) reviewed bedside diagnosis of MI in adults presenting to the emergency department with chest pain unrelated to trauma and unexplained by radiography.1 The diagnosis of acute MI was determined by elevated cardiac isoenzymes and electrocardiography (ECG) changes. Factors that most reliably predicted acute MI were pain radiation to the right arm or shoulder (sensitivity = 15% to 41%; specificity = 94% to 95%; positive likelihood ratio [LR+] = 4.7; 95% confidence interval [CI], 1.9 to 12) and radiation to the left arm (sensitivity = 34% to 55%; specificity = 76%; LR+ = 1.8; 95% CI, 1.1 to 2.8). Factors associated with a decreased likelihood included pleuritic pain (sensitivity = 3% to 6%; specificity = 74% to 82%; LR+ = 0.2; 95% CI, 0.2 to 0.3), sharp pain (sensitivity = 8% to 16%; specificity = 59% to 70%; LR+ = 0.3; 95% CI, 0.2 to 0.5), and positional pain (sensitivity = 3% to 11%; specificity = 75% to 87%; LR+ = 0.3; 95% CI, 0.2 to 0.5).
A systematic review of 14 studies (N = 32,241) compared elements of acute chest pain in patients presenting to the emergency department or admitted to the hospital for suspected MI.2 The diagnosis was determined by cardiac enzymes, ECG changes, or discharge diagnosis. Characteristics that most reliably predicted acute MI were pain radiation to both arms (LR+ = 7.1; 95% CI, 3.6 to 14), radiation to the right shoulder (LR+ = 2.9; 95% CI, 1.4 to 6.0), pain in
1. Chun AA, et al. Bedside diagnosis of coronary artery disease: a systematic review. Am J Med. 2004;117(5):334–343.
2. Panju AA, et al. Is this patient having a myocardial infarction? JAMA. 1998;280(14):1256–1263.
3. Goodacre S, et al. How useful are clinical features in the diagnosis of acute, undifferentiated chest pain? Acad Emerg Med. 2002;9(3):203–208.
Help Desk Answers provides answers to questions submitted by practicing family physicians to the Family Physicians Inquiries Network (FPIN). Members of the network select questions based on their relevance to family medicine. Answers are drawn from an approved set of evidence-based resources and undergo peer review. The strength of recommendations and the level of evidence for individual studies are rated using criteria developed by the Evidence-Based Medicine Working Group (http://www.cebm.net/?o=1025).
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This series is coordinated by John E. Delzell Jr., MD, MSPH, Assistant Medical Editor.
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