From the Departments of Medicine (Drs Panju and Guyatt), Clinical Epidemiology and Biostatistics (Dr Guyatt), and McMaster Medical Programme (Dr Hemmelgarn), McMaster University, Hamilton, Ontario; and the Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, Duke University Medical Center, Durham, NC (Dr Simel). Dr Hemmelgarn is currently a resident in internal medicine at the University of Calgary, Alberta.
The Rational Clinical Examination section editors: David L. Simel,
MD, MHS, Durham Veterans Affairs Medical Center and Duke University Medical
Center, Durham, NC; Drummond Rennie, MD, Deputy Editor (West), JAMA.
When faced with a patient with acute chest pain, clinicians must distinguish
myocardial infarction (MI) from all other causes of acute chest pain. If MI
is suspected, current therapeutic practice includes deciding whether to administer
thrombolysis or primary percutaneous transluminal coronary angioplasty and
whether to admit patients to a coronary care unit. The former decision is
based on electrocardiographic (ECG) changes, including ST-segment elevation
or left bundle-branch block, the latter on the likelihood of the patient's
having unstable high-risk ischemia or MI without ECG changes. Despite advances
in investigative modalities, a focused history and physical examination followed
by an ECG remain the key tools for the diagnosis of MI. The most powerful
features that increase the probability of MI, and their associated likelihood
ratios (LRs), are new ST-segment elevation (LR range, 5.7-53.9); new Q wave
(LR range, 5.3-24.8); chest pain radiating to both the left and right arm
simultaneously (LR, 7.1); presence of a third heart sound (LR, 3.2); and hypotension
(LR, 3.1). The most powerful features that decrease the probability of MI
are a normal ECG result (LR range, 0.1-0.3), pleuritic chest pain (LR, 0.2),
chest pain reproduced by palpation (LR range, 0.2-0.4), sharp or stabbing
chest pain (LR, 0.3), and positional chest pain (LR, 0.3). Computer-derived
algorithms that depend on clinical examination and ECG findings might improve
the classification of patients according to the probability that an MI is
causing their chest pain.
Panju AA, Hemmelgarn BR, Guyatt GH, Simel DL. Is This Patient Having a Myocardial Infarction? JAMA. 1998;280(14):1256–1263. doi:10.1001/jama.280.14.1256
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