Electrocardiogram Differentiation of Benign Early Re Polarization Versus Acute Myocardial Infarction by Emergency Physicians and Cardiologists

8/3/2019 Electrocardiogram Differentiation of Benign Early Re Polarization Versus Acute Myocardial Infarction by Emergency P…

http://slidepdf.com/reader/full/electrocardiogram-differentiation-of-benign-early-re-polarization-versus-acute 1/6

Electrocardiogram Differentiation of BenignEarly Repolarization Versus Acute MyocardialInfarction by Emergency Physicians and

CardiologistsSamuel D. Turnipseed, MD, Aaron E. Bair, MD, J. Douglas Kirk, MD, Deborah B. Diercks, MD,

Poroshat Tabar, DO, Ezra A. Amsterdam, MD

Abstract

Objectives: ST-segment elevation (STE) related to benign early repolarization (BER), a common normal

variant, can be difficult to distinguish from acute myocardial infarction (AMI). The authors compared the

electrocardiogram (ECG) interpretations of these two entities by emergency physicians (EPs) and cardiol-

ogists.

Methods: Twenty-five cases (13 BER, 12 AMI) of patients presenting to the emergency department with

chest pain were identified. Criteria for BER required four of the following: 1) widespread STE (precordialgreater than limb leads), 2) J-point elevation, 3) concavity of initial up-sloping portion of ST segment, 4)

notching or irregular contour of J point, and 5) prominent, concordant T waves. Additional BER criteria

were 1) stable ECG pattern, 2) negative cardiac injury markers, and 3) normal cardiac stress test or angi-

ography. AMI criteria were 1) regional STE, 2) positive cardiac injury markers, and 3) identification of cul-

prit coronary artery by angiography in less than eight hours of presentation. The 25 ECGs were distributed

to 12 EPs and 12 cardiologists (four in academic medicine, four in community practice, and four in commu-

nity academics [health maintenance organization] in each physician group). The physicians were informed

of the patients’ age, gender, and race, and they then interpreted the ECGs as BER or AMI. Undercalls (AMI

misdiagnosed as BER) and overcalls (BER misdiagnosed as AMI) were calculated for each physician group.

Results: Cardiologists correctly interpreted 90% of ECGs, and EPs correctly interpreted 81% of ECGs. The

proportion of undercalls (missed AMI/total AMI) was 2.8% for cardiologists (95% confidence interval [CI] =

0.09% to 5.5%) compared with 9.7% for EPs (95% CI = 4.8% to 14.6%) (p = 0.02). The proportion of overcalls

(missed BER/total BER) was 17.3% for cardiologists (95% CI = 11.4% to 23.3%) versus 27.6% for EPs (95%

CI = 20.6% to 34.6%) (p = 0.03). The mean number of years in practice was 19.8 for cardiologists (95% CI =19 to 20.5) and 11 years for EPs (95% CI = 10.5 to 12.0) (p < 0.001).

Conclusions: Although correct interpretation was high in both groups, cardiologists, who had significantly

more years of practice, had fewer misinterpretations than EPs in distinguishing BER from AMI electrocar-

diographically.

ACADEMIC EMERGENCY MEDICINE 2006; 13:961–967 ª 2006 by the Society for Academic Emergency

Medicine

Keywords: benign early repolarization, acute myocardial infarction, electrocardiogram

The proven benefit of urgent coronary reperfusion

for patients with acute myocardial infarction (AMI)

necessitates rapid recognition of ST-segment ele-

vation myocardial infarction (STEMI) by emergency phy-

sicians (EP). However, AMI is the etiology of ST-segment

elevation (STE) in a minority of patients presenting with

chest pain.1,2 Among the multiple causes of noninfarc-

tion electrocardiographic (ECG) patterns that may mimic

STEMI are benign early repolarization (BER), left bun-

dle branch block, left ventricular aneurysm, left ven-

tricular hypertrophy, paced ventricular rhythms, and

From the Department of Emergency Medicine (SDT, AEB, JDK,

DBD, PT) and Department of Internal Medicine, Division of Car-

diovascular Medicine (EAA), University of California, Davis,

Medical Center, Sacramento, CA.

Received November 3, 2005; revisions received January 24, 2006,

and March 4, 2006; accepted April 8, 2006.

Address for correspondence and reprints: Samuel D. Turnip-

seed, MD, Department of Emergency Medicine, University of

California, Davis, Medical Center, 4150 V Street, Suite 2100, Sac-

ramento, CA 95817. Fax: 916-734-7950; e-mail: sdturnipseed@

ucdavis.edu.

ª 2006 by the Society for Academic Emergency Medicine ISSN 1069-6563

doi: 10.1197/j.aem.2006.04.014 PII ISSN 1069-6563583 961

mailto:[email protected]







pericarditis. The potential for these conditions to be con-

fused with STEMI is reflected in the report of Sharkey

et al., in which 11% of patients receiving a thrombolytic

agent were subsequently found not to have AMI.3

Benign early repolarization, a normal variant, is a rela-

tively frequent ECG finding and can be particularly diffi-

cult to distinguish from AMI in patients presenting to the

emergency department (ED) with chest pain. It is foundin approximately 1% of the population; the majority of

these individuals are younger than 50 years of age and

are rarely older than 70 years.4 African American men

between the ages of 20 and 40 years comprise a large

proportion of this group.5,6 In patients presenting to

the ED with STE, Brady et al. found that BER was almost

as common as AMI (15% vs. 13%).1 In the report by Shar-

key et al. citing an 11% frequency of erroneous adminis-

tration of a thrombolytic agent, almost one third of

patients without AMI had BER.3

It is essential to recognize BER to avoid subjecting pa-

tients to unnecessary medications or procedures. The

risks of thrombolytic therapy include an 8% rate of major

bleeding, of which 1%–2% are intracerebral hemor-

rhages usually resulting in devastating stroke.7 Unneces-

sary emergency percutaneous coronary intervention is

also associated with an unfavorable risk/benefit profile.

On the other hand, misinterpretation of AMI as BER de-

prives patients of potential lifesaving therapy. Because of

the continuing challenge of distinguishing BER from

STEMI, we compared the ECG interpretations of these

two entities by EPs and cardiologists.

METHODS

Study Design

This was a retrospective study that compared ECG inter-

pretations by EPs and cardiologists in terms of AMI vs.

BER. The study was approved by our institutional review

board.

Study Setting and Population

The initial ECGs of each patient were distributed to 12

EPs and 12 cardiologists who were blinded to the final

diagnosis. To achieve diversity among the ECG readers,

we chose physicians from three unique practice environ-

ments. Of these 12 physicians in each of the two groups,

four in each group practiced at our academic training

center, four practiced at a large local health maintenance

organization (teaching) community hospital, and four

were in community practice. All cardiologists involved

in the study routinely evaluated and admitted patients

from the ED. The number of years practiced after com-

pletion of training was recorded for each physician.

Study Protocol

We selected 25 ECGs of patients who had presented to

the ED with the chief complaint of chest pain and who

had complete cardiac evaluations. The ECGs included

13 with BER and 12 with STEMI. BER ECGs were chosen

from our Chest Pain Evaluation Unit database under the

heading ‘‘ECG Interpretation: BER.’’ Criteria for BER

have been previously established8 and are listed in Table

1. In our study, the diagnosis of BER required four of the

five criteria (Figure 1). Additional criteria of BER used in

this study included the following: 1) ECGs demonstrated

a stable pattern, 2) patients had at least three consecutivenegative cardiac injury markers (creatine phosphoki-

nase-MB and/or troponin I), and 3) patients had a normal

noninvasive cardiac stress test or normal coronary angi-

ography. STEMI ECGs were chosen from a computer-

generated list using the International Classification of

Disease billing code for AMI. The criteria for AMI were

Table 1

Benign Early Repolarization Criteria

At least four of the following:

1. Widespread ST-segment elevation (precordial greater than

limb leads)

2. J-point elevation

3. Concavity of initial up-sloping portion of ST segment

4. Notching or irregular contour of J point5. Prominent, concordant T waves (large amplitude)

Adapted from Brady and Chan.8

Figure 1. Typical example of an electrocardiogram demonstrating benign early repolarization in a 43-year-old African Amer-

ican man. All five criteria for benign early repolarization (Table 1) are present.

962 Turnipseed et al. BENIGN EARLY REPOLARIZATION VS AMI



as follows: 1) regional STE, 2) positive serial cardiac in-

jury markers, and 3) coronary angiography within eight

hours of the patient’s arrival in the ED that identified

the culprit vessel.

Chest pain was the chief complaint in all 25 cases. ECG

readers were informed of the age, gender, and race of the

patient for each ECG. No other clinical data were pro-

vided.Readers were askedto interpret each ECG as eitherBER or AMI. It was also clearly stated that if STEMI was

selected, the reader should assume the patient would

receive thrombolytic therapy, not intervention in a cathe-

terization laboratory. ECG interpretations were then col-

lected by a single researcher. Physician interpretations

were classified as correct, undercall, and overcall. Under-

calls were defined as AMI misdiagnosed as BER, and

overcalls were defined as BER misdiagnosed as AMI.

Data Analysis

Physician groups’ continuous data were expressed us-

ing mean or median and then were compared using

Student’s t-test where appropriate. Proportion and

frequency data related to ECG interpretations were

compared using Fisher’s exact test. To account for clus-

tering of repeated measures, a generalized linear model

was used for linear regression analysis. When appropri-

ate, 95% confidence intervals (CIs) are presented. All

tests were based on two-tailed alternatives. We per-

formed the statistical analyses using Stata 7.0 (Stata

Corp., College Station, TX) for Windows (Microsoft

Corp., Redmond, WA).

RESULTS

The number of interpretations for each specialty group

was calculated by multiplying the number of physiciansin each group ( n = 12) by the number of ECGs ( n = 25),

yielding a total of 300 interpretations for each group.

The cardiologists correctly interpreted 90% (269/300;

95% CI = 86% to 93%) of the ECGs, and the EPs’ inter-

pretations were correct in 81% (243/300; 95% CI = 76%

to 85%) of cases (Table 2). The average number of correct

interpretations for the individual cardiologists was 22

(range, 20–24) and for each EP was 20 (range, 15–23).

The proportion of undercalls (AMI misdiagnosed as

BER) was different between specialty groups. Overall,

the proportion of undercalls (missed AMI/total AMI)

was 2.8% for cardiologists (95% CI = 0.09% to 5.5%)

compared with 9.7% for EPs (95% CI = 4.8% to 14.6%)

(p = 0.02). The proportion of overcalls (BER misdiag-

nosed as AMI) was also different between specialty

groups. The proportion of overcalls (missed BER/total

BER) was 17.3% for cardiologists (95% CI = 11.4% to

23.3%) versus 27.6% for EPs (95% CI = 20.6% to 34.6%)

(p = 0.03). The percentage of correct ECG interpretations

by specialty and type of ECG is shown in Table 3. A com-

monly missed BER ECG is shown in Figure 2, and a

commonly missed AMI ECG is shown in Figure 3.There was a disparity of years in practice between spe-

cialty groups. Among the cardiology group, the mean

number of years in practice was 19.8 (95% CI = 19 to

Table 2

Cardiologist and Emergency Physician Interpretations

Cardiologists

Emergency

Physicians

p-

value

Total correct ECGs 90% (269/300) 81% (243/300)

Average no. correct

ECGs per physician

22 20

Proportion undercalls 2.8% (4/144) 9.7% (14/144) 0.02Proportion overcalls 17.3% (27/156) 27.6% (43/156) 0.03

Average years

practiced

19.8 11.0 <0.001

Undercalls = acute myocardial infarction misdiagnosed as benign early

repolarization; overcalls = benign early repolarization misdiagnosed as

acute myocardial infarction.

Table 3

Percentage of Correct ECG Interpretations by Physician Specialty and Type of ECG

Condition ECG No.

Patient

Age (yr)

Patient

Gender

Patient

Race

% Emergency Physicians

Correct (n = 12)

% Cardiologists

Correct (n = 12)

BER 1 54 Male African American 58 92


BER 5 56 Female African American 66 75

BER 6 60 Male African American 75 58BER 12 41 Male White 75 50




BER 22 57 Male White 66 92



AMI 4 52 Male White 92 100


AMI 8 55 Male Hispanic 83 92

AMI 13 52 Male Hispanic 92 100




All ECGs that were correctly interpreted by all physicians of both groups were excluded from the table.

BER = benign early repolarization; AMI = acute myocardial infarction.

ACAD EMERG MED September 2006, Vol. 13, No. 9 www.aemj.org 963



20.5). The EPs, however, had only been in practice for a

mean of 11 years (95% CI = 10.5 to 12.0) (p < 0.001).

ECG misdiagnoses (both overcalls and undercalls) corre-

lated inversely with years in practice for all 24 physicians

considered as a single group (Figure 4). Among misdiag-

nosed ECGs (overcalls and undercalls in both physician

groups), the mean number of years in practice was 13

(95% CI = 12 to 15). In contrast, the mean number of years

of practice reported among those who correctly

diagnosed the ECGswas16 (95%CI = 15to 16.5) (p= 0.001).

After adjusting for covariates (specialty training, years

in practice, practice location, and diagnosis) and cluster-

ing of physician responses, the most significant variable

contributing to a correct diagnosis was the presence of AMI (b coefficient, 0.16; 95% CI = 0.08 to 0.24; p < 0.001).

DISCUSSION

Our study demonstrates the difficulty in differentiating

BER from STEMI. The range of correct answers for the

25 ECGs among the cardiologists and EPs was 15–24.

The cardiologists had fewer undercalls and overcalls

compared with the EPs. However, the cardiologists had

also practiced significantly longer than the EPs. It is note-

worthy that after adjusting for covariates (specialty train-

ing, years in practice, practice location, and diagnosis)

and clustering of physician responses, the most signifi-

cant variable associated with a correct diagnosis was

the presence of AMI. This finding suggests that BER

and STEMI can be distinguished electrocardiographi-

cally in a majority of patients by experienced clinicians

but that frequent errors of overcalls and undercalls will

still unavoidably exist.

Benign early repolarization is a ‘‘pseudoinfarction’’ECG pattern frequently encountered in the ED. Of 171

patients presenting to an ED with STE, Brady et al. found

that BER was the cause in 12%.9 This finding has been as-

sociated with inappropriate administration of fibrinolytic

therapy to patients with BER.3 In patients admitted to the

hospital with ECG findings of STE, Brady et al. compared

Figure 2. A commonly misdiagnosed electrocardiogram with benign early repolarization. The incorrect diagnosis of acute

myocardial infarction was made by 38% of all physician readers in the study.

Figure 3. A commonly misdiagnosed electrocardiogram with acute myocardial infarction. The incorrect diagnosis of benign

early repolarization was made by 17% of all physician readers in the study.




the interpretation of STE by EPs with the cardiologists’

final interpretation that was supported by clinical test-

ing. The rate of ECG STE misinterpretation was 6% by

the EPs.10 A survey involving hypothetical patients with

chest pain and ECGs that demonstrated different etiolo-

gies of STE such as AMI, left ventricular hypertrophy,

and BER was administered to 458 attending and resi-

dent physicians. These physicians were asked to decide

whether fibrinolytic therapy should be given (assumingno contraindications), and it was selected appropriately

in 83% (1,525/1,832) of cases. BER was the diagnosis in

23% of cases in which fibrinolytic therapy was given

inappropriately.11

Despite the clinical importance of differentiating BER

from STEMI, the literature pertaining to this problem is

limited. Regional STE defines STEMI in a patient with

compatible symptoms until proven otherwise and recip-

rocal ST depression further supports the diagnosis.12

Although both AMI and non-AMI causes of STE may

demonstrate a similar number of leads with STE,2 STE

in BER is less likely to be isolated to one ECG region

than is AMI.

13

Additionally, the use of current computer-ized ECG retrieval allows the clinician to readily access

previous ECGs in cases where they are in fact available.

Comparative ECGs are invaluable in distinguishing

BER from AMI.

Patients whose ECGs demonstrate BER should be

encouraged to carry a wallet-sized ECG.14 However,

when only the ED ECG is available, a number of steps

in interpretation are helpful in arriving at the correct di-

agnosis. Serial ECGs that show no change suggest BER.

In a report by Sharkey et al. of patients presenting with

AMI, 16% did not exhibit STE until the second or third

ECG.3 In addition, the presence of at least four of the

five criteria in Table 1 supports BER. It should be noted,

however, that although a notch in the J point (usually in

the precordial leads) has been considered indicative of

BER, this finding has not been systematically studied.15

The value of upward concavity of elevated ST segments

was assessed by Brady et al. In their study, nonconcave

ST elevation had a sensitivity and specificity for AMI of

77% and 97%, respectively, and a positive and negativ e

predictive value for AMI of 94% and 88%, respectively.9

If these steps are performed and the diagnosis remains

unclear, a review of the ECG, faxed to the on-call cardi-ologist, may be of benefit.

Immediate coronary angiography affords a definitive

diagnosis in patients with chest pain and STE of uncer-

tain etiology. In the absence of a cardiac catheterization

laboratory, echocardiography may be helpful in detect-

ing wall motion abnormalities in patients presenting

with AMI. However, emergency echocardiography is

limited by its inability to define the age of a wall motion

abnormality. When the diagnosis remains unclear and

neither angiography nor echocardiography is available,

consideration can be given to transfer a stable patient

to an institution with these capabilities. While several di-

agnostic tools may be available to distinguish the etiol-

ogy of STE, ECG interpretation remains fundamental.

This study demonstrates that both cardiologists and

EPs have difficulty differentiating BER from AMI elec-

trocardiographically. As shown in Table 3, only seven

ECGs were correctly diagnosed by all physicians in

both groups. Thus, physicians must have heightened

awareness that one of these entities may ‘‘masquerade’’

as the other and thus attempt to optimize the use of avail-

able resources to establish the correct diagnosis.

LIMITATIONS

A limitation of our study was the use of a hypothetical sit-

uation wherein the ECG reader did not have the advan-tage of a history and examination of the patient, serial

or previous ECGs, or the ability to obtain consultation.

However, it was our specific purpose to isolate and eval-

uate the success rate of the ECG interpretation among

groups of experienced clinicians. It is clear from prior lit-

erature that the miss rate of AMI is lower when the over-

all clinical picture is available.16 A further limitation is

the relatively small number of readers. However, to our

knowledge, this is the first study to compare ECG inter-

pretation of STE between physicians of different special-

ties in different practice settings. Finally, our findings

may not apply to other institutions.

CONCLUSIONS

In conclusion, 1) BER, a common ECG finding, can be

difficult to distinguish from AMI, 2) cardiologists who

had significantly more years of clinical practice had

fewer undercalls and overcalls than EPs in distinguishing

BER from AMI electrocardiographically, and 3) clinical

experience may be an important factor in differentiating

BER from AMI on ECG.

References

1. Brady WJ, Perron AD, Martin ML, Beagle C, Aufder-

heide TP. Cause of ST segment abnormality in ED

chest pain patients. Am J Emerg Med. 2001; 19:25–8.

Figure 4. Physician years of experience versus number of

missed diagnoses (benign early repolarization + acute myo-

cardial infarction) of the 25 study electrocardiograms.

ACAD EMERG MED September 2006, Vol. 13, No. 9 www.aemj.org 965



2. Brady WJ, Perron AD, Ullman EA, et al. Electrocar-

diographic ST segment elevation: a comparison of

AMI and non-AMI ECG syndromes. Am J Emerg

Med. 2002; 20:609–12.

3. Sharkey SW, Berger CR, Brunette DD, Henry TD.

Impact of the electrocardiogram on the delivery of

thrombolytic therapy for acute myocardial infarction.

Am J Cardiol. 1994; 73:550–3.4. Mehta MC, Jain AC. Early repolarization on scalar

electrocardiogram. Am J Med Sci. 1995; 309:

305–11.

5. Thomas J, Harris E, Lassiter G. Observations on the

T wave and S-T segment changes in the precordial

electrocardiogram of 320 young Negro adults. Am J

Cardiol. 1960; 5:468–74.

6. Klatsky AL, Oehm R, Cooper RA, Udaltsova N, Arm-

strong MA. The early repolarization normal variant

electrocardiogram: correlates and consequences.

Am J Med. 2003; 115:171–7.

7. Weaver WD, Simes RJ, Betriu A, et al. Comparison of

primary coronary angioplasty and intravenous throm-

bolytic therapy for acute myocardial infarction. JAMA.

1997; 278:2093–8.

8. Brady WJ, Chan TC. Electrocardiographic manifes-

tations: benign early repolarization. J Emerg Med.

1999; 17:473–8.

9. Brady WJ, Syverud SA, Beagle C, et al. Electrocardio-

graphic ST-segment elevation: the diagnosis of acute

myocardial infarction by morphologic analysis of the

ST segment. Acad Emerg Med. 2001; 8:961–7.

10. Brady WJ, Perron A, Ullman E. Errors in emergency

physician interpretation of ST-segment elevation in

emergency department chest pain patients. Acad

Emerg Med. 2000; 7:1256–60.

11. Brady WJ, Perron AD, Chan T. Electrocardiographic

ST-segment elevation: correct identification of acutemyocardial infarction (AMI) and non-AMI syndromes

by emergency physicians. Acad Emerg Med. 2001; 8:

349–60.

12. Brady WJ, Peron AD, Syverud SA, et al. Reciprocal

ST segment depression: impact on the electrocardio-

graphic diagnosis of ST segment elevation acute my-

ocardial infarction. Am J Emerg Med. 2002; 20:35–8.

13. Brady WJ. Benign early repolarization: electrocardio-

graphic manifestations and differentiation from other

ST segment elevation syndromes. Am J Emerg Med.

1998; 16:592–7.

14. Smith SW. ST-elevation acute myocardial infarction:

a critical but difficult electrocardiographic diagnosis.

Acad Emerg Med. 2001; 8:382–5.

15. Mehta M, Jain AC, Mehta A. Early repolarization.

Clin Cardiol Rev. 1999; 22(2):59–65.

16. McCarthy BD, Beshansky JR, D’Agostino RB, Selker

HP. Missed diagnoses of acute myocardial infarction

in the emergency department: results from a multi-

center study. Ann Emerg Med. 1993; 22:579–82.

Please see accompanying video Data Supplement available at www.aemj.org .

Colles Fracture Reduction Using Ultrasound

Case: A 28-year-old intoxicated woman presented to the emer-

gency department with right wrist pain and deformity after a

fall during an altercation. We confirmed a Colles fracture with

x-rays (Figure 1). The fracture was also visualized using a 7.5-

MHz ultrasound probe (Figure 2). After adequate sedation, the

fracture was reduced and visualized at the bedside using ultra-

sound, which revealed persistent, slight malalignment (Figure 3).

Further reduction and utilization of repeat ultrasound visuali-zation efficiently achieved optimal alignment (Figure 4), which

was confirmed by standard post-reduction x-rays (Figure 5).

The four-minute video available as a Data Supplement ( http://

www.aemj.org/cgi/content/full/j.aem.2006.07.013/DC1) explains

in detail the use of ultrasound during Colles fracture reduction.

Nate Unkefer, MD

Scott Joing, MD

Rob Reardon, MD

Hennepin County Medical Center

Minneapolis, MN

Figure 1. X-ray showing the initial diagnosis of the Colles

fracture.


http://www.aemj.org/

http://-/?-

http://-/?-

http://www.aemj.org/

Documents

Electrocardiogram Differentiation of Benign Early Re Polarization Versus Acute Myocardial Infarction by Emergency Physicians and Cardiologists