missed ACS


Missed ACS is a common source of medico-legal cases. In the Canadian Medical Protective Association’s 2010 article Delay in diagnosis of ACS, they identified 292 ACS related medico-legal cases in the previous decade, and identified common problems: “incomplete history, delay in testing, incomplete testing, and misinterpretation of diagnostic tests.


What’s the scale of the problem? In the New England Journal of Medicine’s 2000 study Missed diagnoses of Acute Cardiac Ischemia in the Emergency Department, the authors prospectively collected charts on 10,000 patients across 10 hospitals in the early 1990s, 17% of whom had AMI/UA. They found


  • 889 patients with AMI, 2.1% discharged with misdiagnosis of noncardiac chest pain, pulmonary condition, or stable angina; there was an 11% disagreement on STE on the ECG interpreted by blinded cardiologist.
  • 966 unstable angina, 2.3% discharged with misdiagnosis of stable angina, atypical chest pain.
  • Risk factors for misdiagnosis included: women less than 55, non-white, shortness of breath, nondiagnostic ECG.


There are also issues with suboptimal treatment, according to the American Heart Journal 2008 study Missed opportunities for reperfusion therapy for ST-segment elevation myocardial infarction: Results of the Emergency Department Quality in Myocardial Infarction (EDQMI) study. Looking at more than 2000 patients presenting to five Emergency Departments in the US in the early 2000s, 22% STEMI patients did not receive reperfusion. The reasons

  • STE not identified
  • LBBB not documented as new or old
  • withheld for inappropriate reason: intermittent/prolonged/resolved pain


Given that the ECG is central to the diagnosis of ACS and that it’s a skill subject to individual variation, it’s not surprising that (mis)reading ECG is a major factor in missed ACS. There are two issues here

  1. interpreting STE that exists, including its differential (eg BER, LVH, aneurysm, pericarditis)


The latter provides a thorough overview of high risk ischemic signs

  1. STD V1-4: posterior STEMI (LCX) –> 15 lead ECG
  2. prominent T waves: early subendocardial
  3. STD V1-4 + tall T (deWinter T): evolving STEMI
  4. V1-3 flip T: LAD subocclusion
  5. V1-4 deep T wave inversion (Wellens): LAD subocclusion
  6. STE aVL/I without STD V1-2: anteriolat STEMI
  7. STE aVL/I _ diffuse STD: left main/3VD occlusion


  1. consider ACS, including in young patients, with chest/arm pain, SOB, tired/weak, epigastric pain/dyspepsia
  2. carefully read the ECG, including 15 lead and serial ECG
  3. consider the differential for ST changes
    1. STE = ELEVATIONS: Electrolyte (hyperK), LBBB, Early repol, Ventricular hypertrophy, Aneurysm, Thrombus (MI), Inflammation (pericarditis), Osborne waves, Non-occlusive vasospasm, Sudden death (Brugada)
    2. STD = DEPRESSED: Dilated CMO, Enlarged ventricle, Potassium loss, Reciprocal change, Embolism, Subendocardial, Shock, Encephalon bleed, Digoxin
    3. Early R-wave = R-WAVED: RBBB, WPW, ACS (posterior), Ventricle hypert (RVH), Electrode, Dystrophy
    4. T wave inversion = FLIPPED: Fascicles (BBB), LVH, Ischemia, Pulmonary embolism, Pediatric, Encephalon bleed, Digoxin


You can use the HEARTS approach to ECG to look for signs of ischemia in every area:


One thought on “missed ACS

  1. Pingback: Medico-legal error in the Emergency Department |

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