(Circulation. 1998;97:2274-2275.)
© 1998 American Heart Association, Inc.
Images in Cardiovascular Medicine |
Electrocardiographic Diagnosis of Acute Myocardial Infarction During Ventricular Pacing
Roland R. Brandt, MD;
Stephen C. Hammill, MD;
; Stuart T. Higano, MD
From the Division of Cardiovascular Diseases and Internal Medicine, Mayo
Clinic and Foundation, Rochester, Minn.
Correspondence to Stuart T. Higano, MD, Mayo Clinic and Foundation, Division of Cardiovascular Diseases, 200 First St SW, Rochester, MN 55905. E-mail higano{at}mayo.edu
A 51-year-old man
presented to the emergency room with a 30-minute history of
sudden, severe, crushing retrosternal chest discomfort with radiation
to both shoulders. Cardiac risk factors included a history of tobacco
abuse and a family history of premature coronary
atherosclerosis. A single-chamber pacemaker programmed
to the VVI mode had been implanted 12 years earlier for a
bradycardia-tachycardia syndrome, and the patient was
considered pacemaker dependent. Physical examination was unremarkable.
A previous baseline ECG (Figure 1
) was
compared with the ECG on admission (Figure 2) that
showed significant ST-T–segment changes in the interim. The patient
underwent emergency coronary angiography that revealed an
occluded proximal left circumflex coronary artery with minimal
other disease (Figure 3). Primary
percutaneous coronary angioplasty was
performed, and the remainder of the hospital course was uneventful.
View larger version (76K):
[in this window]
[in a new window]
|
Figure 1. Baseline ECG showing ventricular
pacing at 69 pulses per minute, with typical repolarization
abnormalities and underlying atrial fibrillation.
|
|
View larger version (91K):
[in this window]
[in a new window]
|
Figure 2. ECG during acute myocardial infarction, showing
ventricular pacing at 69 pulses per minute and underlying
atrial fibrillation with new ST-T–wave changes compared with baseline
ECG (Figure 1 ). ST-segment depression of 2 mm in leads
V2 and V3 and ST-segment elevation of 1 mm
in leads V5 and V6 are now present.
ST-T–segment changes are concordant (in same direction) with QRS
complex, a finding atypical for pacing-induced repolarization.
|
|
View larger version (133K):
[in this window]
[in a new window]
|
Figure 3. Coronary angiography (right anterior
oblique view with caudal angulation) during acute myocardial infarction
showing total occlusion of proximal left circumflex
artery.
|
|
The ECG is the most important source for the early diagnosis of an
acute myocardial infarction. This information will influence the
decision to restore coronary blood flow with
thrombolytic agents or direct angioplasty.
Pacing-induced repolarization changes may mask acute myocardial injury.
Various ECG criteria have been proposed in the past as indicators for
myocardial infarction during ventricular
pacing.1 The QRS complex during transvenous right
ventricular apical pacing resembles that of spontaneously
occurring left bundle-branch block, and the ST-T–segment
changes are usually discordant from the QRS complex. From the
GUSTO-1 trial experience of 131 patients with acute myocardial
infarction in the presence of left bundle-branch
block,2 three ECG criteria were found to have
independent value in the diagnosis of acute myocardial infarction:
ST-segment elevation of 
1 mm in the presence of a positive QRS
complex; ST-segment depression of 1 mm in lead
V1, V2, or
V3; and ST-segment elevation of 5 mm in
the presence of a negative QRS complex. Although the first two criteria
were present in our patient, the sensitivity and specificity of
these criteria in the diagnosis of acute myocardial infarction during
ventricular pacing are unknown. However, despite the
presence of ventricular pacing, the ECG findings with
concordant ST-T–segment changes were highly suggestive of myocardial
injury.
Footnotes
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke's Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke's Episcopal Hospital and Texas Heart Institute, 6720 Bertner Ave, MC1–267, Houston, TX 77030.
References
-
Barold SS, Falkoff MD, Ong LS, Heinle
RA. Electrocardiographic diagnosis of myocardial infarction during
ventricular pacing. Cardiol Clin. 1987;5:403–417.[Medline]
[Order article via Infotrieve]
-
Sgarbossa EB, Pinski SL, Barbagelata A,
Underwood DA, Gates KB, Topol EJ, Califf RM, Wagner GS, for the GUSTO-1
investigators. Electrocardiographic diagnosis of evolving acute
myocardial infarction in the presence of left bundle-branch block.
N Engl J Med. 1996;334:481–487.[Abstract/Free Full Text]
