A 63-year-old woman with labile hypertension presented to the emergency department (ED) with new onset chest discomfort and an initial blood pressure of 210/100 mm/Hg. Her electrocardiogram (ECG) was unchanged from previous studies and her symptoms resolved with treatment of the hypertension. She was admitted overnight with orders for a morning ECG and serial troponin (ST) levels, the first of which was normal. At 6:00 AM, a nursing assistant obtained the ordered ECG and placed it in the patient's bedside chart without notifying a nurse or physician.
When the team was rounding 2 hours later, they reviewed the ECG, which was notable for new ST elevations inferiorly and laterally. The computer readout of the ECG stated, "****ACUTE MI****" and cited the ST elevations. On questioning the patient, she did report intermittent chest pressure overnight that was less severe than it was when she presented. Her morning troponin level also returned elevated, which was consistent with an acute myocardial infarction (MI). After urgent evaluation, she underwent successful coronary angiography and placement of two stents. She was discharged home without complications and on appropriate medical therapy.
The case raised concerns about the review of ECGs routinely performed in the hospital setting and often by those without the skills to interpret them. In this case, the nursing assistant later reported that she wasn't sure that "MI" meant "heart attack," but she also said that she doesn't routinely look at the computer interpretations. It was unclear whether the delay of 2 hours influenced the patient's outcome, but it could have.
1. Wright RS, Anderson JL, Adams CD, et al; American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. 2011 ACCF/AHA focused update incorporated into the ACC/AHA 2007 Guidelines for the Management of Patients with Unstable Angina/Non-ST-Elevation Myocardial Infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines developed in collaboration with the American Academy of Family Physicians, Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons. J Am Coll Cardiol. 2011;57:e215-e367. [go to PubMed]
2. Alpert JS. Can you trust a computer to read your electrocardiogram? Am J Med. 2012;125:525-526. [go to PubMed]
Table. Common ECG pitfalls in diagnosing myocardial infarction
False positives |
• Early repolarization |
• Left bundle branch block (LBBB) |
• Pre-excitation |
• J point elevation syndromes (e.g., Brugada syndrome) |
• Pericarditis/myocarditis |
• Pulmonary embolism |
• Subarachnoid hemorrhage |
• Metabolic disturbances, such as hyperkalemia |
• Cardiomyopathy |
• Lead transposition |
• Cholecystitis |
• Persistent juvenile pattern |
• Malposition of precordial ECG electrodes |
• Tricyclic antidepressants or phenothiazines |
False negatives |
• Prior myocardial infarction with Q-waves and/or persistent ST elevation |
• Right ventricular pacing |
• LBBB |