Download Comparison of Late Potentials for 24 Hours Between Brugada

Comparison of Late Potentials for 24 Hours Between
Brugada Syndrome and Arrhythmogenic Right Ventricular
Cardiomyopathy Using a Novel Signal-Averaging System
Based on Holter ECG
Atsuko Abe, MD; Kenzaburo Kobayashi, MD; Hitomi Yuzawa, MD; Hideyuki Sato, MD;
Shunji Fukunaga, MD; Tadashi Fujino, MD; Yoshifumi Okano, MD; Junichi Yamazaki, MD;
Yosuke Miwa, MD; Hideaki Yoshino, MD; Takanori Ikeda, MD
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Background—Late potentials (LP) detected with signal-averaged ECGs are known to be useful in identifying patients at risk
of Brugada syndrome (BS) and arrhythmogenic right ventricular cardiomyopathy (ARVC). Because the pathophysiology
is clearly different between these disorders, we clarified the LP characteristics of these disorders.
Methods and Results—This study included 15 BS and 12 ARVC patients and 20 healthy controls. All BS patients had
characteristic ECG changes and symptomatic episodes. All ARVC patients had findings that were consistent with recent
criteria. Three LP parameters (filtered QRS duration, root mean square voltage of the terminal 40 ms of the filtered QRS
complex, and duration of low-amplitude signals [<40 μV] in the terminal, filtered QRS complex) were continuously
measured for 24 hours using a novel Holter-based signal-averaged ECG system. The incidences of LP determination
in BS (80%) and ARVC (91%) patients were higher than in healthy controls (5%; P<0.0001 in both) but did not differ
between BS and ARVC patients. In BS patients, the dynamic changes of all LP parameters were observed, and they were
pronounced at nighttime. On the contrary, these findings were not observed in ARVC patients. When the SD values of the
3 LP parameters (filtered QRS duration, root mean square voltage of the terminal 40 ms of the filtered QRS complex, and
duration of low-amplitude signals [<40 μV] in the terminal, filtered QRS complex) over 24 hours were compared for the
2 patient groups, those values in BS patients were significantly greater than those in ARVC patients (P<0.0001 in all).
Conclusions—LP characteristics detected by the Holter-based signal-averaged ECG system over 24 hours differ between
BS and ARVC patients. Dynamic daily variations of LPs were seen only in BS patients. This may imply that mechanisms
of lethal ventricular arrhythmia in BS may be more correlated with autonomic abnormality than that of ARVC. (Circ Arrhythm Electrophysiol. 2012;5:789-795.)
Key Words: Brugada syndrome ■ arrhythmogenic right ventricular cardiomyopathy ■ late potentials
■ signal-averaged electrocardiogram ■ Holter monitoring
T
he Brugada syndrome (BS),1–3 which is characterized by
a pattern of right bundle branch blocks and ST-segment
elevations in leads V1 and V2 on an ECG, is considered to be a
primary electric disease of the heart caused by a defect in the
ion channel gene, resulting in abnormal electrophysiological
activity in the right ventricle and a propensity to malignant ventricular arrhythmias. On the other hand, arrhythmogenic right
ventricular cardiomyopathy (ARVC)4,5 is a primary myocardial
disease, often familial, that is characterized histologically by
structural abnormalities of the right ventricle because of replacement by fibrous and fatty tissue. The clinical manifestation of
this disease is lethal ventricular arrhythmias, which occasionally cause sudden cardiac death because of a degenerated myocardium. With both disorders, although their pathophysiology
is clearly distinct, it has been reported that a conduction delay
in the right ventricle plays an important role in arrhythmogenesis.4–6 Several studies7–10 have reported an overlap between the
characteristics of BS and ARVC, such as ECGs similar to those
with BS for ARVC patients with a sodium channel blocker7 and
fibrofatty replacement similar to that for ARVC found in right
ventricular biopsies in BS patients.8,9
Clinical Perspective on p 795
Late potentials (LPs) detected by signal-averaged ECGs
(SAECGs), which reflect a conduction delay, have been
widely used to detect high-risk individuals among patients
with cardiac disorders, such as myocardial infarctions, BS,11,12
and ARVC.13–15 At present, it is possible to monitor LPs continuously for 24 hours using a newly developed SAECG system that is applied to Holter ECG recordings.16
Received December 13, 2011; accepted May 9, 2012.
From the Department of Cardiovascular Medicine, Toho University Faculty of Medicine, Tokyo, Japan (A.A., K.K., H. Yuzawa, H.S., S.F., T.F., Y.O.,
J.Y., T.I.); and Second Department of Internal Medicine, Kyorin University School of Medicine, Tokyo, Japan (Y.M., H. Yoshino).
Correspondence to Takanori Ikeda, MD, PhD, Department of Cardiovascular Medicine, Toho University Faculty of Medicine, 6-11-1 Omori-nishi,
Ota-ku, Tokyo 143-8541, Japan. E-mail [email protected]
© 2012 American Heart Association, Inc.
Circ Arrhythm Electrophysiol is available at http://circep.ahajournals.org
789
DOI: 10.1161/CIRCEP.111.969865
790 Circ Arrhythm Electrophysiol August 2012
In the present study, we assessed the value of monitoring
LPs continuously for 24 hours using the developed signalaveraging system to compare daily varying LP characteristics
and to investigate the clinical differentiation of arrhythmogenesis for BS and ARVC.
Methods
Patient Enrollment
BS Patients
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Fifteen patients (13 men and 2 women; mean age, 42±12 years)
who were referred to our medical centers between 2005 and 2011
were enrolled. All the patients showed typical Brugada-type ECGs
(ie, a coved pattern of ST-segment elevations in the V1 and V2
leads), including transiently spontaneous changes during the sinus
rhythm on 12-lead ECGs. In other words, patients who only had the
saddle-back pattern were excluded from the study. In addition, all
BS patients had a history of syncope or life-threatening arrhythmic
events. Before diagnosing BS, we excluded patients who had evidence of organic heart disease, including ARVC, myocardial ischemia of the right ventricle, and other infiltrative cardiomyopathies.
These diagnoses were based on the Report of the Second Consensus
Conference in 20053 using echocardiography, coronary angiography with acetylcholine, other diagnostic techniques, such as scintigraphy, helical computed tomography scanning, and magnetic
resonance imaging, and endomyocardial biopsies in some cases. As
a result, all BS patients studied were believed to have structurally
normal hearts.
ARVC Patients
During the same period, we enrolled 12 patients (9 men and 3 women;
mean age, 33±12 years), who had right ventricular dilation determined using imaging modalities and diagnosed with ARVC as their
clinical findings fulfilled the Task Force Criteria of 2010.6 All patients
underwent 12-lead ECGs, echocardiography, other diagnostic techniques, such as scintigraphy, helical computed tomography scanning,
and magnetic resonance imaging, as well as those for BS. The dilation and reduced wall motion in the right ventricle were observed in
all ARVC patients. In addition, all ARVC patients underwent endomyocardial biopsies for diagnosis and to rule out ARVC phenocopies,
such as cardiac sarcoidosis. We excluded patients who did not have
either documented ventricular arrhythmias or syncopal episodes.
Before enrollment of patients with both cardiac disorders, informed
consent was obtained from each patient. The study was approved
by the ethics committees of Kyorin University Hospital and Toho
University Medical Center.
Controls
Twenty healthy controls (16 men and 4 women; mean age, 40 ± 11
years), who had routine healthcare examinations at the healthcare
department of our institutes between 2006 and 2008, were included
in the study. They are matched for age and sex to BS patients. All controls underwent a 24-hour Holter ECG to measure LPs for 24 hours
similar to the 2 patient populations.
Measurements
Detection of Continuous LPs by the Signal-Averaging System
In this study, LPs were analyzed for 24 hours using a newly developed signal-averaging system (SCM-6600; Fukuda Denshi Co, Ltd,
Tokyo, Japan), which is capable of analyzing LPs automatically every
30 minutes using data from a digital Holter ECG recorder (FM-180;
Fukuda Denshi Co. Ltd).16 This system was developed using the same
algorithm as is applied in FDX-650011 from Fukuda Denshi Co, Ltd,
and is now commercially available in Japan.
This analysis is based on the quantitative time-domain measurements of the filtered vector magnitude of the orthogonal X, Y, and Z
leads. The QRS complexes (>200 beats) were amplified, digitized,
averaged, and filtered with a high-pass filter (40 Hz). Three parameters
were assessed using a computer algorithm: the filtered QRS duration
(fQRS), the root mean square voltage of the terminal 40 ms of the
­filtered QRS complex (RMS40), and the duration of low-amplitude
signals (<40 μV) in the terminal, filtered QRS complex (LAS40).
These 3 parameters were assessed using a computer algorithm, every
30 minutes for 24 hours, and the values for the parameters were presented on a trend graph covering the 24 hours.
Before the present study, we did a preliminary study to assess the
correlation between the Holter-based SAECG (SCM-6600) and standard SAECG (FDX-6500), which used the same method. Twenty
subjects, including both 10 patients (3 with dilated cardiomyopathy, 5
with coronary artery disease, and 2 with BS) and 10 healthy controls,
were measured using the 2 SAECG manufactures simultaneously.
No subjects demonstrated ventricular conduction disturbance, such
as bundle branch block and persistent atrial tachyarrhythmias, on the
12-lead ECGs. First, all 20 subjects had the Holter-based SAECG
examination for 24 hours and then underwent the standard SAECG
examination in the supine position on the same day. Three parameters (fQRS, RMS40, and LAS40) for LP determination were measured
and compared between the 2 manufactures in the same time period
by Pearson product-moment correlation coefficient as statistical
analysis. The correlation coefficient for fQRS, RMS40, and LAS40
­between the 2 measurements in all subjects was 0.98 (P<0.0001),
0.97 (P<0.0001), and 0.95 (P<0.0001), respectively. Consequently,
we concluded that there is correlation of 3 LP parameters between the
standard SAECG and Holter-based SAECG. Kelen et al17 supported
the results of our preliminary study.
Through the use of this system, we assessed daily variations in LP
parameters in 15 BS patients and 12 ARVC patients. All LP acquisitions were performed without the use of antiarrhythmic drugs. The
LPs were considered positive when 1 of the 3 criteria (fQRS>135 ms,
RMS40<15 μV, and LAS40>39 ms)16,18,19 was met, with maximum values over 24 hours.
Statistical Analysis
Data of age in each group are expressed as mean±SD. Data of LP
parameters are presented as the median with first and third quartiles
(25%–75%). Differences among the BS patients, ARVC patients, and
controls were examined using an extension of a Fisher exact probability test for a 3 × 2 table for categorical data (ie, the incidence of
LPs) and a Kruskal-Wallis test as the nonparametric analysis for continuous data (ie, numerical values of fQRS, RMS40, and LAS40). If the
global test is significant among the 3 groups, we conduct pair-wise
comparisons using the Bonferroni procedure that adjusts for multiple
comparisons. P<0.05 was considered statistically significant. All statistical analyses were performed using a statistical software, SPSS
version 15.0 for Windows (SPSS Inc, Chicago, Ill).
Results
Characteristics of BS and ARVC Patients
The characteristics of 15 BS and 12 ARVC patients are summarized in Table 1. With regard to the features of 12-lead
ECGs, a coved pattern of ST-segment elevations was demonstrated in all BS patients. An epsilon wave was documented in
4 ARVC patients.
All patients in both groups had a history of at least 1 event,
which was defined as either a ventricular arrhythmia (8 in BS
patients and in all ARVC patients) or a syncopal episode (11
in BS patients and 10 in ARVC patients). In 8 BS patients
with ventricular arrhythmias, ventricular fibrillation or polymorphic ventricular tachycardia (VT) was documented, but
sustained monomorphic VT was not. On the contrary, in 10
of 12 ARVC patients with ventricular arrhythmias, sustained
monomorphic VT was documented by ambulatory monitoring ECGs or 12-lead ECGs, and the remaining 2 patients had
either ventricular fibrillation or polymorphic VT.
Abe et al Comparison of LPs for Brugada Syndrome and ARVC 791
Table 1. Characteristics of BS and ARVC Patients Enrolled in
This Study
BS Patients
(n=15)
ARVC Patients
(n=12)
Age (mean±SD), yr
42 ± 12
33 ± 12
Sex, male (%)
13 (87)
9 (75)
3 (20)
4 (33)
Variables
Family history of SCD (%)
ECG features (%)
Coven pattern ST elevation
Epsilon wave
15 (100)
…
…
4 (33)
History of events (%)
Syncope
11 (74)
10 (83)
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Aborted sudden death
4 (27)
2 (17)
Document of ventricular arrhythmias
8 (53)
12 (100)
VF and polymorphic VT
8 (53)
2 (17)
Sustained VT
0 (0)
10 (83)
Daytime
4 (27)
12 (100)
Nighttime
11 (73)
0 (0)
Time of events (%)
BS indicates Brugada syndrome; ARVC, arrhythmogenic right ventricular
cardiomyopathy; SCD, sudden cardiac death; VF, ventricular fibrillation; VT,
ventricular tachycardia.
In consideration of the time of events, 11 (73%) BS patients
had events at night or in the early morning (22:00 to 08:00
hours). No life-threatening events occurred during exercise in
the BS patients. Conversely, all 12 ARVC patients had events
during the day (08:00 to 22:00 hours). The events occurred
during physical exercise in 6 (50%) ARVC patients.
Comparisons of LP Parameters
The test results of LP parameters in 15 BS and 12 ARVC
patients and controls are shown in Table 2. For BS patients,
LPs were determined in 12 (80%) patients. For ARVC patients,
LPs were identified in 11 (91%) patients. In healthy controls,
LPs were identified in only 1 (5%) subject. The incidences
of LP determination were significantly different among the 3
groups. Subsequently, pair-wise comparisons between BS and
ARVC patients and controls were performed. The incidences
of LP determination in BS and ARVC patients were higher
than that in healthy controls (P<0.0001 in both) but did not
differ significantly for both BS and ARVC patients.
The numerical values of fQRS, RMS40, and LAS40 for
LP determination were significantly different among the 3
groups. Subsequently, pair-wise comparisons between BS and
ARVC patients and controls were performed. The numerical
value of fQRS in BS patients was significantly lower than that
in ARVC patients (P=0.0004), but the values of RMS40 and
LAS40 did not differ between both patients. When compared
between BS patients and controls, the values of fQRS, RMS40,
and LAS40 in BS patients were significantly greater than those
in healthy controls (P<0.0001 in all).
Daily Variation of LP Parameters
In all BS patients, dynamic daily variations of LP parameters
were observed. Figure 1 shows a representative example of the
trend graphs of each LP parameter (fQRS, RMS40, LAS40) in a
BS patient. All parameters fluctuated over 24 hours, and measured values of LP parameters increased at night and decreased
during the day. In this patient, the maximum LP values were
recorded from 03:00 to 05:00 hours (middle of the night) and
the minimum values from 12:00 to 14:00 hours (afternoon).
In 11 (73%) of the 15 BS patients, similar trend graphs were
recorded. LPs were identified, and events occurred at night
in these 11 patients. In contrast, the dynamic daily changes
of LP parameters were not observed in any ARVC patient
(Figure 2), whereas LPs were identified in most (91%) of the
ARVC patients.
Because LP parameters showed dynamic change in BS
patients, we calculated the SD of the continuous values of
QRS, RMS40, and LAS40 from each patient over 24 hours (ie,
daily variation of the parameters) and compared these values
for the 3 groups (Table 2). The SD of a patient’s observations
over 24 hours of each LP parameter was significantly different
among the 3 groups. We did pair-wise comparisons between
BS and ARVC patients and controls. All SD values of BS
patients were significantly higher than those of ARVC patients
(P<0.0001 in all). We also compared each value between BS
Table 2. Comparisons of LP Parameters for BS and ARVC Patients and Controls
BS Patients (n=15)
Determinate LP (%)
fQRS, ms
ARVC Patients (n=12)
Controls (n=20)
P Value
12/15 (80)*
11/12 (91)*
1/20 (5)
0.003
147 (139–150)†‡
160 (156–163)†
122 (118–125)
<0.0001
RMS40, µV
10.8 (8.2–16.8)†
11.5 (10.4–12.9)†
26.5 (18.2–32.2)
<0.0001
LAS40, ms
47.0 (42.5–50.5)†
47.3 (44.0–54.0)†
35.3 (30.0–36.8)
<0.0001
SD over 24 hours of fQRS, ms
4.52 (3.41–5.72)†§
1.26 (0.89–1.68)
1.73 (1.50–2.44)
<0.0001
SD over 24 hours of RMS40, µV
2.81 (2.44–4.05)†§
0.89 (0.83–1.02)
1.22 (0.98–1.41)
<0.0001
SD over 24 hours of LAS40, ms
4.50 (4.14–4.96)†§
1.37 (1.37–1.97)
1.39 (1.20–1.59)
<0.0001
LP indicates late potentials; BS, Brugada syndrome; ARVC, arrhythmogenic right ventricular cardiomyopathy; fQRS, filtered QRS duration; RMS40, root mean square
voltage of the terminal 40 ms of the filtered QRS complex; LAS40, duration of low-amplitude signals (<40 μV) in the terminal, filtered QRS complex.
LP parameters are shown as medians with 25%–75% values. P values are attained by a single test that compares 3 groups simultaneously. These were done using
an extension of a Fisher exact test for a 3 × 2 table for categorical data and a Kruskal-Wallis test for continuous data.
*P<0.0001 by a Fisher exact test comparing controls.
†P<0.0001 by the Bonferroni procedure as pair-wise comparisons comparing controls.
‡P=0.0004 and §P<0.0001 by the Bonferroni procedure as pair-wise comparisons comparing ARVC patients.
792 Circ Arrhythm Electrophysiol August 2012
A
D
B
E
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C
Figure 1. Dynamic change of late potential (LP) parameters used for LP determination of a Brugada syndrome patient. A, Filtered QRS
duration (fQRS), (B) root mean square voltage of the terminal 40 ms of the filtered QRS complex (RMS40), (C) duration of low-amplitude
signals (<40 μV) in the terminal, filtered QRS complex (LAS40), (D) filtered QRS complex at time of minimum value of fQRS, and (E) filtered
QRS complex at time of maximum value of fQRS. The arrows on A, B, and C indicate maximum and minimum values of each parameter.
The 3 parameters dynamically change, and the maximum values are recorded at night.
patients and controls. Similarly, all SD values of BS patients
are significantly higher than controls (P<0.0001 in all).
Discussion
The major finding of the present study was to document the
different dynamics of LPs detected by SAECG over 24 hours,
for both BS and ARVC. Although the incidences of LPs that
reflect depolarization abnormalities or conduction delays
were high for both disorders, BS patients had daily variations
of LPs with nighttime ascendancy, but ARVC patients did not.
This finding may reveal that the pathophysiology of lethal
ventricular arrhythmias differs for both BS and ARVC. The
pathophysiological mechanism of LPs in BS patients with a
structurally normal heart may be closely associated with both
depolarization abnormality and autonomic modulation.
The characteristic 12-lead ECG features of BS are dynamic
and often concealed.20 Modulation abnormalities of the
autonomic system may directly affect the ECG properties
and increase vulnerability to fatal arrhythmias.21,22 Several
reports23–26 showed, for BS patients, that ST-segment elevations on 12-lead ECGs have diurnal and daily variations;
therefore, it is considered that the occurrence of events may
also have circadian and daily variations. Matsuo et al26 analyzed the circadian pattern of 30 ventricular fibrillation
episodes in 12 BS patients who underwent an implantable
cardioverter-defibrillator treatment and reported that ventricular fibrillation occurred more frequently at night (93%) than
during the day (7%). In this study, 73% of episodes of BS
patients occurred at night or in the early morning. The remaining 27% of episodes occurred during the daytime. Of note,
no patients had life-threatening events during exercise. The
circadian pattern of the events in our population was similar to
those of previous studies.26
In contrast, islands of fibrofatty tissues generate the
arrhythmogenic substrate and form an electric reentrant circuit for malignant ventricular arrhythmias responsible for
serial events in ARVC patients. These arrhythmias are typically induced by adrenergic stimulation, such as a catecholamine infusion or physical exercise. It has been shown that
physical exercise is a precipitating factor for lethal ventricular
arrhythmias in patients with ARVC.5 Corrado et al27 reported
that sudden cardiac death occurred among young ARVC
patients, and Leclercq et al28 documented VT on a 24-hour
Holter ECG after an autonomic imbalance of increasing sympathetic tone in ARVC patients. Furthermore, it has been
reported that adrenergic stimulation, an isoproterenol infusion mimicking the catecholamine effect, induced VT with
ARVC.29 Succinctly, VT with ARVC is the result of sympathetic stimulation but not vagal tone. In this study, the events
during the day, when physical activity is high, occurred in all
ARVC patients. Conversely, none of the patients had an event
Abe et al Comparison of LPs for Brugada Syndrome and ARVC 793
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Figure 2. No dynamic change of late potential (LP) parameters used for LP determination of an arrhythmogenic right ventricular cardiomyopathy patient. A, Filtered QRS duration (fQRS), (B) root mean square voltage of the terminal 40 ms of the filtered QRS complex (RMS40),
(C) duration of low-amplitude signals (<40 μV) in the terminal, filtered QRS complex (LAS40), (D) filtered QRS complex at time of minimum
value of fQRS, and (E) filtered QRS complex at time of maximum value of fQRS. The 3 parameters are almost fixed throughout the 24 hrs.
at night. The events occurred during physical exercise in 50%
of the ARVC patients.
The presence of LPs is an established marker that is useful
for risk stratification in patients with structurally abnormal
hearts, for example, patients having had a myocardial infarction.30,31 Several clinical studies support that LPs are a strong
predictor for risk stratification of malignant arrhythmias with
BS as well.11,12,25 However, with ARVC, the clinical values
are still controversial as to whether they are markers of the
pathophysiological substrate, namely fibrofatty substrate, or
the index of vulnerability to ventricular arrhythmias.15 The
relationship between the features of ECGs (epsilon wave
and inverted T wave in leads V1 and V2) and LPs is still
unknown.
By assessing LPs by SAECGs over 24 hours for BS
patients who have been identified as having a high risk for
lethal ventricular arrhythmias, a dynamic manner of changes
for LP parameters were found during this study. These
dynamic changes were accentuated at night, and all the LP
parameters at night were greater than during the day. In contrast, all the values of LP parameters for ARVC over 24 hours
did not fluctuate as largely as they did in BS patients. The
SD values of the LP parameters over 24 hours for the ARVC
patients were significantly less than those for BS patients.
ARVC patients who were identified as being at high risk for
ventricular arrhythmias were considered as being less likely
to be influenced by autonomic balance in comparison with
BS patients, because no clear peak for either night or day was
observed. Therefore, the role of LPs in ARVC may be as a
pathophysiological substrate rather than electric instability.
The analysis of LPs over 24 hours may play an important role
as a noninvasive technique for diagnosing both disorders in
their early stages.
Clinical Implications
In identifying patients with BS and ARVC at high risk for serious arrhythmic events, noninvasive methods are more desirable than invasive or genetic methods. Our study shows that,
for asymptomatic BS patients, the detection of LPs using the
SAECG system with a 24-hour Holter ECG could be a useful
technique for identifying the subgroup at high risk for arrhythmic events. If such patients have dynamic changes of LPs over
24 hours, with night ascendancy, they could be considered
candidates for an implantable defibrillator.
One application of the information from this study would
be to consider doing SAECG using commercial non-Holter–
based SAECG 2×: (one in the middle of the night and the other
in the afternoon). These are the times reported at maximum
daily changes of LPs in this study. However, the Holter-based
SAECG would be necessary when we assess daily variations
of LPs in BS patients because BS patients are awake (not
794 Circ Arrhythm Electrophysiol August 2012
sleeping) to undergo the standard SAECG and have the same
situation as daytime.
Study Limitations
In this study, we only analyzed LPs as a tool to determine
electrophysiological abnormalities and did not realize the
value of other markers, such as electrophysiological testing,
drug infusion tests, and genetic analysis, which were assessed
in previous studies.
Because we have not investigated daily variations of LPs
in terms of arrhythmic event, an additional or follow-up study
will be necessary to determine the prognostic significance of
LP variability for stratifying patients at risk of BS.
Conclusions
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The LP characteristics detected using SAECG over 24 hours
differ between BS and ARVC patients. LPs in BS patients
dynamically change during the day, whereas this is not the
case for ARVC patients. It may imply that the mechanisms of
lethal ventricular arrhythmias in BS patients are more correlated to autonomic abnormalities than ARVC patients.
Acknowledgment
We thank Takahito Kaji for help with statistical analysis of this study.
Sources of Funding
This work was supported, in part, by Grants-in-Aid (21590909,
21500420, 22136011, and 24591074) for Scientific Research from
the Ministry of Education, Culture, Sports, Science and Technology
of Japan and by the Research Promotion Grant from Toho University
Graduate School of Medicine (No. 12-01 to T.I.).
Disclosures
None.
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CLINICAL PERSPECTIVE
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Late potentials (LP) detected with signal-averaged ECGs are useful for identifying patients at risk of Brugada syndrome (BS)
and arrhythmogenic right ventricular cardiomyopathy (ARVC). Because the pathophysiology is clearly different between
these disorders, we clarified the LP characteristics of these disorders. This study included BS and ARVC patients and healthy
controls. All BS and ARVC patients had clinical findings that were consistent with recent guidelines. Three LP parameters
(filtered QRS duration, root mean square voltage of the terminal 40 ms of the filtered QRS complex, and duration of lowamplitude signals [<40 μV] in the terminal, filtered QRS complex) were continuously measured for 24 hours using a novel
Holter-based signal-averaged ECG system. The incidences of LP determination in BS and ARVC patients were higher than
in healthy controls but did not differ between BS and ARVC patients. In BS patients, dynamic changes of all LP parameters
were observed, and they were pronounced at nighttime. On the contrary, these findings were not observed in ARVC patients.
When the SD values of 3 LP parameters over 24 hours were compared for the 2 patient groups, those values in BS patients
were significantly greater than those in ARVC patients. LP characteristics detected by the Holter-based signal-averaged ECG
system over 24 hours differ between BS and ARVC patients. Dynamic daily variations of LPs were seen only in BS patients.
We presume that mechanisms of lethal ventricular arrhythmias in BS are more correlated with autonomic abnormalities than
those in ARVC.
Downloaded from http://circep.ahajournals.org/ by guest on May 12, 2017
Comparison of Late Potentials for 24 Hours Between Brugada Syndrome and
Arrhythmogenic Right Ventricular Cardiomyopathy Using a Novel Signal-Averaging
System Based on Holter ECG
Atsuko Abe, Kenzaburo Kobayashi, Hitomi Yuzawa, Hideyuki Sato, Shunji Fukunaga, Tadashi
Fujino, Yoshifumi Okano, Junichi Yamazaki, Yosuke Miwa, Hideaki Yoshino and Takanori
Ikeda
Circ Arrhythm Electrophysiol. 2012;5:789-795; originally published online June 4, 2012;
doi: 10.1161/CIRCEP.111.969865
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