Full text of DOI:10.1002/clc.4960260405

Clin. Cardiol. 26, 173–176 (2003)
Diagnostic Yield of Automatic and Patient-Triggered Ambulatory Cardiac Event
Recording in the Evaluation of Patients with Palpitations, Dizziness, or Syncope
NICOLA BALMELLI, M.D., BARBARA NAEGELI, M.D., OSMUND BERTEL, M.D.
Division of Cardiology, Department of Internal Medicine, Triemli Hospital, Zurich, Switzerland.
Summary
Background: Recent studies have shown that patient-trig-
Key words: cardiac event recorders, dizziness, palpitation,
syncope, arrhythmias
gered cardiac event recorders (CER) have an increased diag-
nostic yield and are more cost effective than conventional 24-
h-Holter electrocardiograms (ECGs) for the evaluation of
sporadic, potentially arrhythmia-related symptoms.
Hypothesis: The aim of this study was to determine the di-
agnostic yield of a patient-triggered CER combined with con-
tinuous automatic arrhythmia detection in the evaluation of
sporadic dizziness/syncope or palpitations and its clinical rel-
evance in assessing the further management.
Methods: We investigated 101 consecutive outpatients (54
± 20 years, 40 women), referred for evaluation of sporadic
dizziness and syncope (36%) or palpitations (64%) of suspect-
ed rhythmogenic origin. All were monitored by patient-trig-
gered CER with continuous automatic arrhythmia detection.
Results: After a mean monitoring period of 103 ± 38 h, 83
patients registered symptoms and 57 patients had diagnostic
or therapeutic relevant arrhythmias (relA). A total of 196 epi-
sodes of relA were recorded; 31 (16%) episodes were patient-
triggered and 165 (84%) automatically recorded. Diagnostic
relevant episodes (relA and/or typical symptoms) occurred in
94 patients, in 54% after the first 24 h of monitoring. Accord-
ing to the results of the CER, 80 patients needed no further di-
agnostic evaluation; 20 had additional diagnostic tests.
Conclusions: Cardiac event recorders with a continuous au-
tomatic arrhythmia detection function are a well-tolerated de-
vice for sporadic, potentially arrhythmia-related symptoms.
The patient-triggered mode alone is not sufficiently reliable;
the automatic continuous arrhythmia detection function has
additional diagnostic and therapeutic consequences. In 54%
of all patients, the first diagnostic event would not have been
recorded with a single conventional 24-h-Holter ECG.
Introduction
Unexplained syncope, dizziness, and palpitations are
among the most common reasons that patients present to in-
ternists and cardiologists.1, 2 The diagnostic evaluation with a
conventional 24-h-Holter electrocardiogram (ECG) is some-
times unsatisfactory because of the sporadic and unpredictable
nature of these symptoms, possibly due to cardiac arrhyth-
mias. Therefore, cardiac event recorders (CER) offer an inter-
esting possibility for prolonging the cardiac rhythm monitor-
ing compared with standard Holter systems. According to the
recent literature, patient-triggered CERs seem to be a valid al-
ternative to 24-h-Holter ECGs, as they show an increased di-
agnostic yield and are more cost effective than conventional
24-h- or even 48-h-Holter ECGs.3–7 Until now, most of the
routinely used CERs are patient triggered only, allowing for
registration of an ECG during typical symptoms.3–7 In this
study, a recently released CER was evaluated in patients with
syncope, dizziness, and palpitations. This device features both
automatic and patient-triggered arrhythmia detection up to 7
days of monitoring. Only few data are available about its effi-
cacy and clinical relevance in unselected groups of ambulato-
ry patients.8, 9 The aim of this study was to determine the diag-
nostic yield of this CER, with an added automatic arrhythmia
detection function, in the ambulatory evaluation of sporadic
syncope, dizziness, and palpitations, and to demonstrate its
clinical relevance in assessing further patient management.
Methods
Patients
In all, 101 consecutive patients, referred to our cardiology
unit for evaluation of sporadic (less than one episode per day)
syncope, dizziness, and palpitations, were prospectively en-
rolled in this study. Patients who experienced symptoms daily
were excluded, as were patients in whom history and basic
cardiological workup (physical examination, resting ECG,
echocardiography) revealed the cause of their symptoms, that
is, aortic stenosis, cerebrovascular disease, or arrhythmias pre-
sent in the resting ECG. Baseline patient characteristics and in-
dications for monitoring are shown in Table I.
Address for reprints:
Barbara Naegeli, M.D.
Division of Cardiology, Department of Internal Medicine
Triemli Hospital, Birmensdorferstrasse 497
8063 Zurich, Switzerland
Received: May 18, 2001
Accepted with revision: April 5, 2002

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Clin. Cardiol. Vol. 26, April 2003
TABLE I Baseline charactersitics and indications for monitoring in
101 patients with cardiac event recordings
Results
The study sample consisted of 40 women and 61 men with
Age (years)
Men/women (n)
54 ± 20
61/40
a mean age of 54 ± 20 years. One patient was lost to follow-up.
Of the monitored patients, 36% complained of syncope or
dizziness and 64% of palpitations; 52% had known structural
heart disease. The frequency of symptoms before entering the
study was one to five episodes per week in 30% of the patients,
one to three episodes per month in 28%, less than one to three
episodes per month in 33%, and 9% of the patients had one
single symptomatic episode before referral only. The mean
monitored time period available for analysis was 103 ± 38 h
(equal to 4.3 days of 7 monitoring days).
Indications for monitoring
Palpitations (%)
Dizziness/syncope (%)
Known cardiovascular disease a (%)
Coronary artery disease (%)
Hypertension (%)
65 (64)
36 (36)
53 (52)
29 (29)
9 (9)
Valvular heart disease (%)
Cardiomyopathy (%)
Others (%)
19 (19)
4 (4)
6 (6)
Monitoring time (h)
103 ± 38
During the monitoring period, 83 patients registered symp-
toms (52 patients had palpitations, 29 dizziness, and 2 experi-
enced a syncope) and 57 had relevant arrhythmias (manually
or automatically triggered), as shown in Figure 1. Of the 83
symptomatic patients, 55% showed relevant arrhythmias, in
37% correlating with symptoms. A total of 196 relevant ar-
rhythmias were registered (1.94 arrhythmic episodes per pa-
tient): 8 episodes of ventricular tachycardia, 14 episodes of
ventricular bigeminus, 33 episodes of atrial fibrillation or flut-
ter, 92 episodes of supraventricular tachycardia, 42 bradycar-
dias, and 7 pauses. Thirty-one (16%) episodes were patient-
triggered and 165 (84%) automatically recorded (Fig. 1). Of
the 18 patients who were asymptomatic during the monitoring
period, 11 (61%) had relevant arrhythmias registered by the
automatic arrhythmia detection function only (18 episodes of
supraventricular tachycardia, 6 episodes of atrial fibrillation or
flutter, 6 episodes of ventricular bigeminus, and 1 pause).
According to the results of the CERs, 80 patients had no need
for further evaluation, 23 (29%) required therapy based on the
results, and 57 (71%) could be reassured because of the harm-
less nature of their symptoms (Table II). Twenty patients had
additional diagnostic tests, 6 patients as a direct consequence
of the CER findings (3 ventricular electrophysiologic studies,
2 laboratory tests, and 1 cardiac magnetic resonance imaging
for right ventricular dysplasia), and 14 needed further work-
up because of nonconclusive results (3 head-up tilt tests, 3
neurologic evaluations, 6 repeated R-Tests and 2 24-h-Holter
ECGs). Diagnostically relevant episodes, defined as relevant
arrhythmias and/or typical symptoms, occurred in 94 patients.
Only seven patients had no symptoms or relevant arrhythmias
during the monitoring period. In 54% of these 94 patients, the
first registered event was recorded after the first 24 h of moni-
toring and, therefore, would have been missed with a standard
24-h-Holter ECG. Of the 80 patients who had no need for fur-
ther investigations, 41 (51%) had their first diagnostic event
after the first 24 h of monitoring. Similarly, 12 (60%) of the 20
patients who needed further tests had their first diagnostic
event after the first 24 h. Of the 289 registered patient-trig-
gered ECG strips, 225 (78%) showed normal sinus rhythm,
28 (9%) sinus tachycardia, 31 (11%) relevant arrhythmias,
and only 5 (2%) episodes could not be interpreted because of
a poor recording quality.
a Defined as structural heart disease.
Data are presented as numbers (%) of patients or mean value (± stan-
dard deviation).
Cardiac Event Recorder and Monitoring Protocol
All patients were monitored with a commercially available
CER (R-Test™Evolution, Novacor, France). This new moni-
toring device has a continuous loop analysis of up to 7 days
and a 20-min solid-state memory. It combines patient-trig-
gered recordings with a continuous automatic arrhythmia de-
tection function and features additionally a continuous trend
of heart rate monitoring. Both of these monitoring capabil-
ities can be programmed separately for pre- and post-trigger-
ing delay. The most serious automatic and all patient-trig-
gered events are recorded in a user-defined manner on the
20-min solid-state memory. The R-Test Evolution is able to
register up to 10 categories of arrhythmic events, based on an
algorithm which analyzes QRS prematurity and width, and 1
category of ischemic events. In the current protocol the pre-
and post-triggering delay was programmed to 20 and 10 s, re-
spectively, in the patient-triggered and automatic mode. The
amount of solid-state memory available to each category of
events (automatic and patient triggered) was programmed as
follows: 8 min for pauses (16 events), 5 min for bradycardia
(10 events), 4 min for tachycardia (8 events), and 3 min for
patient-triggered events (6 events). Device setup, data recov-
ery, and data analysis took a total of no more than 45 min. To
obtain an optimal diagnostic yield, patients were asked to use
the device continuously for 7 days.
Data Collection and Data Analysis
The 101 CERs were collected after 7 days. The ECG stripes
of all patient-triggered and automatically recorded events
were analyzed independently by two cardiologists blinded to
the study. Relevant arrhythmias were defined as follows: ven-
tricular tachycardia (>100 beats/min and ≥3 beats), ventricu-
lar bigeminus, supraventricular tachycardia (> 100 beats/min
and ≥3 beats), atrial fibrillation or flutter, bradycardia (< 40
beats/min) and pauses (RR-interval ≥3 s).
Separate analysis for the groups with and without structural
heart disease (53 vs. 48 patients) showed a higher diagnostic

N. Balmelli et al.: Efficacy of cardiac event recorders with an automatic arrhythmia detection function
175
Patients
101
Relevant
arrhythmias
196
Symptomatic
83 (82% )
Asymptomatic
18 (18% )
Automatically triggered
165 (84% )
Patient triggered
31 (16% )
Without relA
37 (45% )
With relA
46 (55% )
Without relA With relA
7 (39% )
11 (61% )
Pts (n) Episodes (n)
Relevant arrhythmias
Episodes (n) Pts (n)
31
14
11
7
74
42
27
8
SVT
Bradycardia (<40 beats/min)
Atrial fibrillation or flutter
VT
18
0
9
0
3
0
4
1
6
0
Patient
triggered
Automatically
triggered
1
8
Ventricular bigeminus
Pause (≥ 3 s)
6
2
6
1
17 (37% )
29 (63% )
(A)
(B)
FIG. 1 (A) Flow diagram for symptomatic and asymptomatic patients during the monitoring period, showing positive and negative clinical cor-
relation between symptoms and registered relevant arrhythmias. Data are presented as numbers (%) of patients. (B) Registered relevant arrhyth-
mias sorted by the triggering mode and type of arrhythmia. Data are presented as numbers (%) of relevant arrhythmia episodes and numbers of
patients. SVT = supraventricular tachycardia, VT = ventricular tachycardia, relA = relevant arrhythmias, Pts = patients.
yield in the group with organic heart disease. In this group,
72% had relevant arrhythmias compared with 40% in the
group without structural heart disease. The number of patients
registering symptoms during the monitoring period was not
significantly different between these two groups: 81% (43/53)
compared with 83% (40/48) (Table III).
of routinely used CERs was the fact that all recordings used
the patient-triggered mode only. We tested a recently released
CER with an added automatic arrhythmia detection function
in the evaluation of sporadic and potentially rhythmogenic
symptoms. Very few data are available about the diagnostic
yield and clinical relevance of combined automatically and
patient-triggered registering devices. Until now, two studies
have evaluated the automatic arrhythmia detection function of
this CER in patients with simultaneously conventional Holter
recordings.8, 9 Simonetti et al., in a group of 31 patients with
syncope, dizziness, and palpitations, found that during a mon-
itoring period of 7 days all relevant arrhythmias registered by
the 24-h-Holter ECG were also recorded by the R-Test Evo-
lution.8 Roche et al., in 103 patients after myocardial infarc-
Discussion
Recent data have confirmed that the diagnosis of cardiac
arrhythmias in the clinical evaluation of syncope, dizziness,
and palpitations can be enhanced by CERs compared with
conventional 24-h-Holter ECGs.3–7 So far, the main limitation
TABLE II Diagnostic and clinical consequences
Further test a
Start therapy b
Reassurance
Unknown
Total
Symptomatic patients
Patient-triggered relA
Automatically triggered relA
No relA
1
6
8
11
7
3
5
16
25
0
0
1
17
29
37
Asymptomatic patients
With relA
Without relA
4
1
20
2
0
23
5
6
57
0
0
1
11
7
101
Total
Data are presented as numbers (n) of patients.
a Three ventricular electrophysiologic studies, two laboratory tests, one cardiac magnetic resonance imaging, three head-up tilt tests, three neuro-
logic evaluations, six repeated R-Tests, two 24-h Holter ECGs.
b Two pacemakers, one ICD, two radiofrequency ablations, 18 drug therapies.
Abbreviations: relA = relevant arrhythmias, ICD = implantable cardioverter defibrillator.

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Clin. Cardiol. Vol. 26, April 2003
TABLE III Analysis for patients with and without structural heart
disease
Limitations
A limitation of the current study is the relatively small sam-
ple of patients studied in a tertiary referral center. An important
issue is the lack of recording during hours when the CER was
not in place (i.e., during bathing), including the possibility of
missing relevant events. A third limitation of this study is that
52% of patients had known cardiovascular pathology and
were likely to have an arrhythmia within the week of monitor-
ing. Therefore, it is possible that such devices would yield the
most benefit in patients with a higher likelihood of having an
event within a week of monitoring, but may not be applicable
in those without structural heart disease who are likely to ex-
perience arrhythmic events much more rarely.
Structural heart disease
Yes
53
No
48
Symptomatic patients
Asymptomatic patients
Relevant arrhythmias
Patient triggered
43
10
38
10
35
40
8
17
7
Automatically triggered
17
Data are presented as numbers (n) of patients.
tion, found that the sensitivity of the R-Test Evolution, com-
pared with a conventional Holter ECG, was 100% in detecting
pauses, bradycardia, atrial fibrillation, and episodes of ven-
tricular bigeminus; 70 to 82% in detecting supraventricular
tachycardias; and 86% in detecting ventricular tachycardias.9
In the same study, while exclusively using the automatic mode
in 35 patients, 6 (17%) of these patients revealed abnormal
ECG findings that occurred beyond the first 24-h period. In
our study, 54% of the patients had their first diagnostic event
after the first 24 h of monitoring, which probably would not
have been recorded with a single 24-h-Holter ECG. Zimet-
baum et al. found that 80% of their patients examined for pal-
pitations had at least one diagnostic event during the first week
of monitoring.4 This result is comparable with the rate of 82%
we found in our cohort. In the same study, the average of 1.04
diagnostic rhythm strips per patient per week was also similar
to the average of 1.09 in our study.
Compared with other CERs, the most important feature of
this device is the added automatic arrhythmia detection func-
tion. This feature was helpful in detecting 84% of all relevant
arrhythmia episodes, and at least one episode of relevant ar-
rhythmia was registered in an additional 61% of our asymp-
tomatic patients. Of those who did not trigger the recording of
any relevant arrhythmia during their symptoms, 63% never-
theless showed relevant arrhythmias in the automatically reg-
istered ECG strips (Fig. 1). Thus, for the ambulatory workup
of suspected sporadic arrhythmias, the patient-triggered func-
tion alone is probably not sufficiently reliable.
Conclusion
Cardiac event recorders, with a continuous automatic
arrhythmia detection function combined with a patient-trig-
gered registering mode, are well tolerated devices for the am-
bulatory evaluation of sporadic, potentially arrhythmia-relat-
ed symptoms. The patient-triggered mode alone is not
sufficiently reliable; the automatic arrhythmia detection func-
tion has additional diagnostic and therapeutic consequences.
In 54% of the patients, the first diagnostic event (relevant ar-
rhythmia and/or typical symptom) occurred after the first 24 h
of monitoring and therefore would not have been recorded
with a single conventional 24-h-Holter ECG.
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Up to now, conventional 24-h-Holter ECGs represented the
standard of reference in the evaluation of potentially rhythmo-
genic symptoms; our data demonstrate the diagnostic yield
and usefulness of CERs as complementary instruments com-
pared with standard Holter technique. The CER was well tol-
erated. Setup, data recovery, and data analysis took no more
than 45 min, even less than for a conventional 24-h-Holter
ECG. The optimal monitoring time for cardiac event recorders
in the examination of sporadic palpitations was found to be 2
weeks. After this period, there is very little additional diagnos-
tic yield compared with rapidly rising costs.4