Use Extra Caution in Interpreting ECG Findings in the Acute Chest Pain Setting
To the Editor: I read with great interest the ECG Rounds article by Drs Reddy and McKiernan (November/December 2006). This case highlights a relatively common finding on diagnostic electrocardiograms (ECG) of early repolarization. As the authors point out, an elevated J point associated with an upwardly concave ST morphology is often associated with normal variant early repolarization. However, in the setting of acute chest pain in the emergency department, we must be cautious in reaching the diagnosis of normal variant early repolarization based on these ECG findings. This issue has long been a source of difficulty for the emergency department physician, and has often resulted in litigation. A minority of patients with ST-elevation myocardial infarction (MI) will present with a mildly elevated ST segment with concave morphology, which has often led to discrepancies in ECG interpretation and misdiagnosis.

One study found this to occur more often in inferior wall infarctions.¹ An upwardly concave ST segment is also a common finding in anterior MI.² A recent retrospective study demonstrated that of 37 consecutive patients who presented to the emergency department with proven left anterior descending occlusion, 16 (43%) had an initial ECG showing upwardly concave morphology involving leads V₂ through V₆.³ Those patients with concave morphology also had a shorter duration of symptoms than would normally be seen in classic ST elevation presentation (P <.05), which should make us even more cautious when dealing with patients who present early in their course of symptoms.

Therefore, I would like to emphasize the need to exercise caution in a patient with acute chest pain and an ECG showing the characteristics of non–acute MI etiologies of ST elevation, in particular, normal variant early repolarization. Many studies have demonstrated that the characteristics used to identify early repolarization can often be found on an ECG of a patient who is having an acute MI.

Shane Dieckman, DO
Emergency Department Staff Physician
Bitburg Annex Hospital, Spangdahlem Air Base, Germany
United States Air Force

1. Erling BF, Perron AD, Brady WJ. Disagreement in the interpretation of electrocardiographic ST segment elevation: a source of error for emergency physicians? Am J Emerg Med. 2004; 22:65-70.

2. Smith SW, Whitwam W. Acute coronary syndromes. Emerg Med Clin North Am. 2006; 24: 53-89, vi.

3. Smith SW. Upwardly concave ST segment morphology is common in acute left anterior descending coronary occlusion. J Emerg Med. 2006; 31:69-77.

The Author Replies: The point made by Dr Dieckman should be emphasized and reiterated. ST-segment elevation on an electrocardiogram (ECG) in the setting of acute chest pain should be reviewed with caution. The ECG is not a perfect test, and many subtle differences are often unrecognized by even the most experienced clinician. ST elevation must be appropriately diagnosed, because the implications of withholding treatment (or providing the wrong treatment) can lead to considerable morbidity and mortality. This highlights the importance of integrating all available data, such as old ECGs, serial enzymes, echocardiogram, or stress testing, to ensure accurate diagnosis and avoid unnecessary, costly, and potentially harmful tests. In addition to the early repolarization variant seen on his ECG, our patient had negative serial enzymes and a normal bedside echocardiograph before discharge.

Proddutur Reddy, MD
Loyola University