CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 7, August 2013
AFRICA
283
The slurring pattern was more frequent in the lateral leads
(DI
=
12%, V6
=
6% and V5
=
4%). The notching pattern was
uniformly distributed in the limb and left precordial leads (DI
and DII
=
20%, VF
=
18%, VL
=
16%, V5 and V6
=
14%;
p
>
0.05).
The prevalence of negative T waves was 3.7% in this
population. In subjects with ER, seven (14%) displayed negative
T waves, whereas only two (1%) without ER had this abnormality
(
p
=
0.00025).
Subjects with ECGs displaying the ER pattern had a more
frequent past history of syncope (
p
=
0.00014). This association
was more pronounced in the subgroup of patients with the
notching variant of ER pattern (
p
=
0.0001), as shown in Table
3. However, we did not find any correlation between the
J-T-segment variations (ascending, descending or horizontal) of
ER and syncope. A family history of SUD was not more frequent
in subjects with ER features (
p
=
ns)
Discussion
In this study, we observed a high prevalence of ER in patients
with a high rate of cardiovascular morbidity. The frequency of
ER pattern found was higher than that reported in the general
population.
1,4
ER and syncope seemed to be linked, especially
the notching pattern. The higher rate of ER in this specific
population of subjects at risk for cardiac diseases could indicate
a possible risk marker, or an ‘innocent bystander’ of this ECG
pattern.
Patients with ER more frequently had negative T waves,
suggesting a select population with a poorer prognosis. This
finding in such a specific population with a poor prognosis
may indicate overlapping of an ER phenotype in cardiovascular
outcomes.
This study, as with several others, highlights the question
of the relationship between ER and syncope.
11,12
Most studies
reporting the clinical significance of ER dealt with the strongest
clinical outcome, which is sudden cardiac death due to ventricular
tachyarrhythmias. As syncope has a heterogeneity of mechanisms
and causes, it is difficult to evaluate its link with ER.
Not all syncopes (e.g. reflex syncope and cardiogenic syncope)
have the same explanation in terms of electrophysiological
properties of ion channel exchanges driving the formation of
J-point elevation (JPE).
13,14
We assumed that non-cardiogenic
syncope was not associated with the JPE pattern.
Some studies have described the variation in J-T-segment
characteristics after the ER waveforms, the so-called descending,
ascending and horizontal morphology, as having prognostic
significance.
15,16
Indeed, a horizontal/descending J-T segment
in the inferior leads was associated with a significant risk of
arrhythmic death, whereas the ascending morphology seemed
to have a benign outcome.
16
In our study, neither ascending nor
horizontal/descending patterns were associated with syncope.
One potential explanation could be the small sample size. We
also emphasise that the heterogeneity of syncope could be a
concern.
Arrhythmogenic syncope as a risk marker of SCD merits
a prospective investigation in subjects with ER pattern. Our
study attempted to put this issue into perspective and discuss the
current knowledge on the prevalence and significance of early
repolarisation.
ER and cardiovascular outcomes
ER seems to be associated with a high risk of cardiac arrest.
3,17-23
The present study was not designed to confirm this finding.
In the absence of other known causes of syncope, it is
difficult to confirm whether ER may be responsible for fainting.
Nevertheless, ER has been found in individuals suffering from
syncope.
11,12,24
Indeed, we previously reported the case of exertion
syncope with only ER in an apparently healthy young adult.
12
Maury
et al
.
24
documented a spontaneous VF by a loop recorder
in a patient with an ECG pattern of ER in the inferior leads, who
presented with syncope.
The current population was highly specific for being at
risk for cardiovascular morbidity, since we studied subjects
referred to a cardiac unit for cardiovascular risk factors such as
hypertension or diabetes as well as for cardiac-related symptoms
(e.g. loss of consciousness). For this reason, the high rate of
reported syncope may be explained by the pre-specified clinical
behaviour of the sample.
Several studies have reported the high prevalence of ER in
young individuals,
21
with disappearance of this pattern over
time (10 years) in 62% of individuals in the Veterans Affairs
Palo Alto cohort.
25
Our findings confirm this result, as the
group of subjects with ER was significantly younger than
those without ER. We hypothesise that ER pattern, which is
an electrocardiographic manifestation of mismatch between
outward and inward trans-membrane ionic currents, is a juvenile
phenotype, which progressively disappears with time.
It would be of interest to establish the distribution of
J-T-segment morphologies (ascending, horizontal/descending)
according to age group. This information may add data to aid
understanding of risk stratification of ER pattern, as the odds of
arrhythmic outcomes follows the life expectancy of each index
individual.
Prognostic markers of ER
Recent studies suggest that ER is not as benign as was earlier
believed. Therefore a careful evaluation of carriers, especially
in those with syncope or ventricular arrhythmias and/or a family
history of sudden cardiac death is justified.
14
Many studies have
attempted to identify markers of malignancy, helping to clarify
the clinical significance of this syndrome.
TABLE 3. COMPARISON BETWEEN SUBGROUPSACCORDING
TOTYPES OF EARLY REPOLARISATION
ER–
(
n
=
197)
ER+ t1
(
n
=
8)
ER+ t2
(
n
=
32)
ER+ t1t2
(
n
=
9)
p
-value
Age (years)
49
±
16 30
±
16 45
±
15 35
±
14 0.0031
Female,
n
(%)
107 (54)
4 (50)
14 (44)
3 (33)
ns
Palpitations,
n
(%) 65 (33)
3 (37)
10 (31)
6 (67)
ns
Syncope,
n
(%)
26 (13)
3 (37)
15 (47)
1 (11) 0.0001
Family SUD,
n
(%) 14 (7)
2 (25)
1 (3)
0
ns
T(–) wave,
n
(%)
2 (1)
1 (
<
1)
4 (2)
2 (1)
0.0004
Bonferroni correction was used to calculate the
p
-value.
ERV–
=
absence of early repolarisation; ERV+
=
presence of early repo-
larisation variant; t1
=
type 1 or slurring pattern; t2
=
type 2 or notching
pattern; t1t2
=
both patterns; T(–) wave
=
negative T wave; TLOC
=
tran-
sient loss of consciousness; SUD
=
sudden unexpected death.
