Admission Clinical and
Electrocardiographic Characteristics
Predicting In-Hospital Development of
High-Degree Atrioventricular Block in
Inferior Wall Acute Myocardial Infarction
Yochai Birnbaum,
MD
, Samuel Sclarovsky,
MD
, Izhak Herz,
MD
,
Bruria Zlotikamien,
MD
, Angela Chetrit,
MSc
, Liraz Olmer,
BSc
, and
Gabriel I. Barbash,
MD
,
MPH
This study assessed the ability of simple clinical and
electrocardiographic variables routinely obtained on
admission to identify patients who are at high risk of
developing high-degree atrioventricular (AV) block dur-
ing hospitalization in 1,336 patients with inferior wall
acute myocardial infarction (AMI). Patients were classi-
fied into 2 initial electrocardiographic patterns based on
the J-point to R-wave amplitude ratio: pattern 1: those
with J point/R wave <0.5 and pattern 2: patients with J
point/R wave >0.5 in >2 leads of the inferior leads II,
III, and aVF. High-degree AV block was found in 6.7% of
patients (41 of 615) with pattern 1 versus 11.8% of the
patients (85 of 721) with pattern 2 on admission elec-
trocardiogram (p ؍ 0.0008). Multivariate logistic re-
gression analysis revealed that the only variables found
to be independently associated with high-degree AV
block were female gender (odds ratio [OR] 1.48; 95%
confidence interval [CI] 0.98 to 2.23; p ؍ 0.06); Killip
class on admission >2 (OR 2.24; CI 1.43 to 3.51; p ؍
0.0004); initial electrocardiographic pattern 2 versus
pattern 1 (OR 1.82; CI 1.22 to 2.21; p ؍ 0.003); and
absence of abnormal Q waves on admission (OR yes vs
no 0.68; CI 0.44 to 1.05; p ؍ 0.08). A simple electro-
cardiographic sign (J point/R wave >0.5 in >2 leads) is
a reliable predictor of the development of advanced AV
block among patients receiving thrombolytic therapy for
inferior wall AMI. ᮊ1997 by Excerpta Medica, Inc.
(Am J Cardiol 1997;80:1134–1138)
A
pproximately 19% of patients with inferior wall
acute myocardial infarction (AMI) develop high-
degree (second or third degree) atrioventricular (AV)
block during hospitalization.
1–7
Most patients experi-
ence AV block within the first 24 hours of infarc-
tion.
2,7–9
Although it is usually transient, high-degree
AV block is associated with increased in-hospital
mortality.
2
In the prethrombolytic era, the average
in-hospital mortality for inferior wall AMI without
AV block was 9%, compared with 23% in patients
with high-degree AV block
2,3,5,7,9,10
and 29% in
patients with third-degree AV block.
2,11–14
High-de-
gree AV block is also associated with increased mor-
tality in patients treated with thrombolytic therapy.
Hospital mortality in the Thrombolysis and Angio-
plasty in Myocardial Infarction (TAMI)-1 trial was
20% versus 4% in patients with and without AV block
(p Ͻ0.001),
15
and 21-day mortality was 7.1% versus
2.7%, respectively, in the Thrombolysis in Myocardial
Infarction (TIMI) II trial (p ϭ 0.007).
16
Increased
mortality, higher rates of left ventricular failure, and
cardiogenic shock were especially associated with
presence of high-degree AV block early in AMI.
9
This
retrospective analysis assessed the prognostic signifi-
cance of simple clinical and electrocardiographic pa-
rameters, available to the clinician immediately upon
admission, to predict development of high-degree AV
block during the index hospitalization in patients with
inferior wall AMI treated with thrombolytic therapy.
METHODS
Patient group:
The study was comprised of patients
enrolled in 25 medical centers in Israel from Septem-
ber 1991 to February 1993. All patients were admitted
within 6 hours of onset of symptoms, had chest pain
lasting Ն20 minutes, had positive T waves, and Ն0.1
mV of ST-segment elevation in Ն2 limb leads II, III,
and aVF. Patients with concomitant anterior and infe-
rior wall AMI were excluded. Patients with additional
ST-segment elevation in the lateral leads V
4
to V
6
or
ST-segment depression in leads I, aVL, or V
1
to V
6
were included if they had ST elevation in leads II,
III, and aVF. Patients with left bundle branch block,
ventricular rhythm, ventricular pacing, or negative T
wave in the leads demonstrating ST-segment elevation
were excluded. Patients received streptokinase, front-
loaded tissue plasminogen activator (t-PA), or a com-
bination of streptokinase and t-PA according to the
Global Utilization of Streptokinase and TPA for Oc-
cluded Arteries (GUSTO)-I protocol.
17
All patients
received oral aspirin 160 to 325 mg/day and either
intravenous or subcutaneous heparin for at least 48
hours.
17
Clinical evaluation and end points:
Gender, age,
history of diabetes mellitus, systemic hypertension,
From the Beilinson Medical Center, Petah-Tiqva; the Sheba Medical
Center, Tel-Hashomer; and Tel Aviv Sourasky Medical Center, Sackler
Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Manuscript
received March 28, 1997; revised manuscript received and ac-
cepted June 26, 1997.
Address for reprints: Gabriel I. Barbash MD, MPH, Tel Aviv
Sourasky Medical Center, 6 Weizman St., Tel Aviv 64239, Israel.
1134
©1997 by Excerpta Medica, Inc. 0002-9149/97/$17.00
All rights reserved. PII S0002-9149(97)00628-0