Circulation. 1997;96:3527-3533
(Circulation. 1997;96:3527-3533.)
© 1997 American Heart Association, Inc.
Evaluation of the Specificity of Morphological Electrocardiographic Criteria for the Differential Diagnosis of Wide QRS Complex Tachycardia in Patients With Intraventricular Conduction Defects
Teresa Alberca, MD;
Jesús Almendral, MD;
Petra Sanz, MD;
Aureliano Almazan, MD;
Jose Luis Cantalapiedra, MD;
;
Juan Luis Delcán, MD
From the Clinical Electrophysiology Laboratory, Departamento de
Cardiología, Hospital General Universitario Gregorio
Marañón, Madrid, Spain.
 |
Abstract
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Background Although several ECG criteria have been
described
for the differential diagnosis of tachycardias
with a wide QRS
complex, their applicability in patients with
preexisting intraventricular
conduction defects
(IVCDs) has been questioned. The specificity
of previously described
criteria in this context is unknown.
Methods and Results We analyzed prospectively the
specificity of the QRS morphological criteria previously described in
ECGs during sinus rhythm of 232 patients with IVCD. Only 5 of 12
analyzed criteria had a specificity 
0.90 among our patients:
(1) a triphasic configuration (Rsr'or Rr') QRS complex in
V1 in the presence of a right bundle-branch block
morphology (BBBM); (2) a QS, QR, or R QRS pattern in V6 in
the presence of a right BBBM; (3) any Q in V6 in the
presence of a left BBBM; (4) a concordant pattern in all precordial
leads; and (5) the absence of an RS complex in all precordial leads
(particularly useful for left BBBM). The following criteria—QRS
duration >140 ms; a left axis with right BBBM, right superior axis
with right BBBM, monophasic or biphasic R wave in V1 with
right BBBM, and a relation R/S <1 with right BBBM; an R >30 ms in
lead V1 or V2 with left BBBM, >60 ms from QRS
onset to S nadir with left BBBM, a notched downstroke S wave with left
BBBM, and an R-to-S interval >100 ms in one precordial lead—had a
specificity of 0.43, 0.54, 0.87, 0.80, 0.85, 0.78, 0.66, 0.69, and 0.63
(0.84 in right BBBM), respectively.
Conclusions Most of the previously described morphological
criteria favoring ventricular tachycardia are
present in a substantial percentage of patients with IVCD during
sinus rhythm. These findings suggest a limited applicability of these
criteria in this subset of patients.
Key Words: bundle-branch block • arrhythmia • diagnosis • electrocardiography • tachycardia
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Introduction
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Several
ECG criteria have been described for the differentiation
between (VT)
and SVT with a wide QRS complex.
1 2 3 Some of
these criteria
involve an analysis of the QRS morphology and
were developed by
comparing tracings of VT to a "control" group
of SVT with BBB. In
fact, in a recent study involving a step-by-step
ECG analysis,
the first two criteria were morphological.
3 One
of the
limitations of those studies is that the control group
involved mostly
patients in whom BBB was functional; patients
with organic BBB were
either excluded
1 2 or unlikely, because
the population was
selected on the basis of an indication for
an
electrophysiological study and such
patients infrequently
have organic BBB. The only study analyzing the
proposed morphological
criteria in patients with organic BBB involved a
small number
of patients and was published before the two new
morphological
criteria were described.
4 Thus, the
available information about
the applicability of the described
morphological criteria to
patients with organic BBB is limited.
To study the specificity of the previously published morphological
criteria in patients with organic BBB, we have prospectively
analyzed the tracings of 232 unselected consecutive patients
admitted to our institution who had IVCDs during sinus rhythm.
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Methods
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Study Design
The 12-lead ECGs performed at our institution from February
1992
to December 1994 were prospectively screened for the following
inclusion
criteria: (1) sinus rhythm, (2) a wide QRS
120-ms QRS
complex,
(3) a constant PR interval of a duration
140 ms, and (4)
admission
to the hospital at the time. Once an ECG meeting the
inclusion
criteria was identified, one of the investigators obtained
clinical
information about the patient by direct questioning and
reviewing
the medical records. The presence of structural heart
disease
was determined from the history and objective evidence on the
basis
of noninvasive and/or invasive diagnostic techniques,
including
two-dimensional echocardiography and
cardiac catheterization
when clinically indicated.
Particular attention was given to
the use of antiarrhythmic drugs
(specially class IA, IC, and
III).
Patient Population
Two hundred thirty-two consecutive patients met the inclusion
criteria. Their clinical characteristics are described in Table 1
(156 men and 76 women). Their ages
ranged from 26 to 91 years (mean±SD, 68±11 years). Clinical and/or
laboratory findings of structural heart disease were present in 151
patients (65%). An estimation of the left ventricular
ejection fraction (by echocardiography and/or
contrast ventriculography) was obtained in 130 patients (56%). The
left ventricular ejection fraction was significantly
depressed (<40%) in 60% of those patients.
ECG Analysis
Among the morphological ECG criteria previously described for
the differential diagnosis of wide QRS complex tachycardia,
we selected for analysis those with 0.90 specificity and
electrophysiological documentation of the
tachycardias studied in the original publication. Criteria
were also included if only applicable to a subset of ECG (ie, those
with left or right BBBM QRS complex or those with RS morphology in any
of the precordial leads3 ). Because these criteria were
meant to be used for the recognition of VT, right and left BBBM was
defined, as it is usually, during VT4 5 6 7 8 : a QRS complex was
considered to have a right BBBM if it had a dominant R wave in
V1; if the dominant wave in V1 was an S wave,
the QRS complex was considered to have a left BBBM. The criteria
selected and analyzed as suggestive of VT were the following:
(1) QRS duration >140 ms1 2 ; (2) left axis deviation (QRS
axis in the frontal plane between -30° and -90°) in the presence
of a right BBBM1 2 ; (3) right superior axis (QRS axis in
the frontal plane between -90° and -180°) in the presence of a
right BBBM4 6 ; (4) monophasic (R) or biphasic (qR, QR, Rs,
or RS) or a rabbit-ear triphasic configuration (Rsr' or Rr') QRS
complex in V1 in the presence of a right
BBBM1 2 4 ; (5) rS, QS, QR, or R configuration in lead
V6 in the presence of a right BBBM1 2 ; (6)
R-wave duration >30 ms in leads V1 or V2 in
the presence of a left BBBM7 ; (7) >60 ms from QRS onset
to the nadir of the S wave in lead V1 or V2 in
the presence of a left BBBM7 ; (8) notched downstroke S
wave in lead V1 or V2 in the presence of a left
BBBM7 ; (9) any q wave in lead V6 in the
presence of a left BBBM7 ; (10) the presence of a
concordant pattern (entirely positive or negative QRS complexes) in all
precordial leads1 2 4 ; (11) absence of an RS patterns
in all precordial leads3 ; and (12) an interval >100
ms from the onset of the R wave to the nadir of the S wave in
precordial leads with an RS morphology.3 According to
the method of Wellens et al,1 2 we considered
"triphasic" the patterns rR' and Rr' (types 3 and 5 of Reference
22 ).
Only one tracing was analyzed per patient. If more than one was
obtained, the tracing with the best technical quality was selected for
analysis.
Statistical Analysis
The mean±SD is reported. To calculate specificity of each
criterion, we considered all of our patients to belong to the
"nondiseased" population, because they did not have actual VT.
However, all the criteria analyzed in the study have been
described for the diagnosis of VT. Thus, cases that were positive for
each criterion were false positives, and those cases that were negative
were true negatives. The specificity for each criterion was calculated
by dividing true negatives (or those negative for that criterion) by
all nondiseased cases (the entire population or the particular subset
to which each criterion can be applied). Categorical variables were
compared with the 
2 test. Statistical
significance was at the level of P<.05.
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Results
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Specificity of the Proposed Criteria
Ninety-nine petients (43%) had a right BBBM, and 133 (57%) had
a
left BBBM.
Table 2 reflects the specificity of
each of the proposed criteria. It can be noted that only 5 of the 12
criteria analyzed had specificity >0.90 (see Figs 1 and 2).
Thus, only 5 of the 12 criteria had a specificity in patients with IVCD
similar to that in patients without IVCD. Three other criteria, all
among those evaluated in patients with right BBBM, had >0.80
specificity (Figs 3 and 4). When criteria were combined, the
specificity decreased, except if only the criteria with excellent
specificity were included. For example, the specificity of the combined
criteria with a specificity 0.80 in the presence of right BBBM (ie,
how many ECGs had either a rabbit-ear triphasic configuration (Rsr'or
Rr') QRS complex in V1 or a QS, QR, or R configuration in
lead V6; a right superior axis; a monophasic (R) or
biphasic (qR, QR, RS) in lead V1, or an rS in lead
V6) was 0.58 (57 of 99). However, if only the two criteria
with a specificity 0.90 were considered, the combined specificity was
high, 0.96 (95 of 99). The specificity of the four combined criteria in
left BBBM was only 0.55 (59 of 132) (Figs 5 and 6).
The consecutive specificity of the first and second criteria described
by Brugada et al3 was also only 0.57 (Fig 7).
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Figure 2. A 12-lead ECG in sinus rhythm with an absence of an
RS complex in all precordial leads with right BBBM.
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Figure 3. A 12-lead ECG in sinus rhythm with right BBBM, a
right superior axis, and a QRS duration >140 ms.
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Figure 4. A 12-lead ECG in sinus rhythm with right BBBM, a
left axis, a biphasic qR in lead V1, a relation R/S <1 in
lead V6, and a QRS duration >140 ms.
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Figure 5. A 12-lead ECG in sinus rhythm with left BBBM, a QRS
duration >140 ms, an R-to-S interval >100 ms in two precordial leads,
and a notched downstroke S wave in V2.
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Figure 6. A 12-lead ECG in sinus rhythm with an R-to-S
interval >100 ms in one precordial lead, with left BBBM, an R wave
in V1 and V2 >30 ms, a Q wave in
V6, and >60 ms from QRS onset to S nadir in V1
and V2.
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Figure 7. A 12-lead ECG in sinus rhythm with an R-to-S
interval >100 ms in two precordial leads, with right BBBM and a
QRS duration >140 ms.
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The criteria that could be applied in both BBBM were also
analyzed separately in patients with right BBBM and with left
BBBM (Table 3). In the presence of right
BBBM, the specificities of the absence of an RS complex in all
precordial leads and an R-to-S interval >100 ms in one
precordial lead were 0.81 and 0.84, respectively (consecutive,
0.68) (Figs 2
and 7). In cases with left BBBM, the specificities were
0.98 and 0.50, respectively (consecutive, 0.50). Figs 5 and 6
illustrate examples of an R-to-S interval >100 ms in ECGs with left
BBBM. There was a significant relationship between the presence of
right BBBM and the absence of an RS complex in all precordial leads
(P<.0001). There was also a significant relationship
between the presence of left BBBM and an R-to-S interval >100 ms in
one precordial lead (P<.0001) (Table 4).
Finally, we analyzed the criteria in the patients ECGs who were
taking class I or III antiarrythmic drugs (Table 5). Seven patients had this
characteristic: 4 were taking amiodarone, 1 was on propafenone,
1 was taking procainamide, and 1 was on quinidine. Six had a
QRS duration >140 ms. The absence of an RS complex in all
precordial leads was not a feature of any of the patients taking
antiarrythmic drugs, but 6 had a R-to-S interval >100 ms in one
precordial lead. Five patients had left BBBM, and the remaining 2
had right BBBM. Interestingly, 3 of the 4 patients with left BBBM in
whom the downstroke of the S wave in V1 or V2
could be evaluated had a notched pattern.
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Discussion
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The main observation of the present study is that the
specificity
of most morphological criteria for the differential
diagnosis
of wide QRS tachycardias decreases in the
presence of IVCD.
Only five criteria were found to have and specificity
>0.90.
It has been suggested that the value of the classic
morphological
criteria for the diagnosis of VT may decrease if
preexistent
BBB is present.
2 4 However, because most
of the studies on
the differential diagnosis of wide QRS
tachycardia were performed
in patients with BBB developed
during tachycardia in the electrophysiology
laboratory
(presumably functional in most of them), the information
regarding the
above suggestion has been limited until now.
In the presence of fixed (ie, nonintermittent) complete BBB and in the
absence of accessory pathways, all beats of
supraventricular (including sinus) origin preferentially
conduct over the contralateral bundle. If all
supraventricular impulses use the same fixed pathway for
activating the ventricle, the QRS morphological pattern is expected to
remain unaltered regardless of rate. Therefore, the QRS morphological
configuration during SVT in patients with preexisting BBB would be
identical to that observed during sinus rhythm.6 8 This
contention supports our approach of an analysis of QRS
morphology during sinus rhythm to assess the specificity of
morphological criteria to be used during tachycardia. Had
our patients developed an SVT, they would have been expected to display
a similar QRS morphology.
We analyzed the 12 previously described morphological criteria
of VT that had a specificity >0.90 in different series. However, in
our ECG, only 5 of them had a specificity >0.90. The sensitivity of
these criteria was quite low for most of them in different studies:
0.11,2 0.31,2 0.55,7
0.03,2 and 0.21,3 respectively. Thus, even
these criteria with high specificities have limited clinical value in
this patient population.
After having stated the former, it is also fair to recognize that if a
specificity 0.80 is considered acceptable for a medical test, other
more sensitive criteria, such as a right superior axis in the presence
of right BBBM, a monophasic R or biphasic (qR, QR, or RS) in
V1, and a relation R/S <1 in V6 in the
presence of right BBBM, could be considered "reasonably" useful
in these patients.
However, some criteria that have been noted to have limited value in
relatively recent studies (not necessarily including patients with
organic BBB) were also found to have a low specificity in the
present series. A QRS duration >140 ms, which has been found to be
of limited value,3 6 9 had a low specificity (0.43) in our
study. A left axis deviation in the presence of right BBBM was not
found to be useful by Wellens et al,2 Akhtar et
al,6 Dongas et al,8 and Brugada et
al3 ; it had a low specificity in the present
series.
In right BBBM, the specificity of combined criteria with a specificity
0.80 is also low (0.58) and cannot be used to accurately diagnose the
origin of wide complex tachycardia with this morphology.
However, only when the two criteria with >0.90 specificity are
combined does the specificity remains high.
The only series that specifically addressed the value of morphological
criteria in patients with organic BBB was that of Kremers et
al.4 This study compared 106 ECGs of VTs in 70 patients
with a sinus rhythm ECG; of this group, 18 patients had preexisting
BBB. They showed a high specificity for three criteria: a monophasic R
wave in V1 in presence of right BBBM (specificity=1.0), an
R wave >30 ms in V1 or V2 with left BBBM
(specificity=1.0), and a right superior axis (specificity=1.0).
The presence of a monophasic R wave in V1 is included
in our study as part of a single criterion, along with a biphasic
pattern in the same lead, and had an 0.80 specificity. It was
analyzed in exactly the same way as its original description.
However, if only the presence of a monophasic R wave was considered,
the specificity would have increased to 0.95, in accordance with the
finding of Kremers et al4 of a high specificity for this
criterion. In contrast, the finding of an R wave >30 ms in patients
with a left BBBM had a lower specificity in our series. However, in the
study by Kremers et al,4 there were only 8 patients with
left BBBM compared with 133 in our series. The QRS axis, as such, was
considered in our analysis only for ECGs with a right BBBM,
because its sensitivity is unknown in ECGs with a left BBBM in the
absence of organic BBB during sinus rhythm. For patients with right
BBBM, its specificity was close to 0.90 (0.87).
A different and simpler approach to address the same problem was
undertaken by Dongas et al.8 They demonstrated that when
the sinus QRS morphology of patients with preexisting BBB is compared
with the wide QRS complex tachycardia morphology of the
same patient, any change in QRS morphology is indicative of a
ventricular origin. However, this criterion is not
applicable when a patient is first seen during tachycardia,
justifying our efforts to recognize the specificity of different
patterns.
While the specificity of the combined criteria described by Kindwall et
al7 was 0.89, in our series, it is only 0.55. However,
only 15 of ECGs (13%) in the series of Kindwall et al had left BBB in
sinus rhythm.
In 1991, two new criteria were included as part of a step-by-step
diagnostic algorithm for the ECG differential diagnosis of
a wide QRS complex tachycardia. In this study, the
specificity of the first criterion was 1.00, and when the second
criterion was applied, the specificity was 0.98. However, the control
group of that study (inducible SVTs) probably included many patients in
whom BBB was functional. Our tracings showed a high specificity (0.91)
for VT if an absence of RS in all precordial leads was present.
However, the low specificity (0.63) for the second criterion (R-to-S
interval >100 ms) and the low consecutive specificity (0.57) could
potentially limit the diagnostic efficiency of the proposed
algorithm in a patient with IVCD should he or she develop SVT. When the
criteria that could be analyzed in both right and left BBBM
were analyzed separately in these two groups of ECGs, some
differences in specificity were noted. An absence of RS complex in all
precordial leads could be particularly useful for left BBBM (seen
in only 2 of 133 ECGs), whereas the converse could be true for an RS
>100 ms in any precordial lead (0.84 specificity in right BBBM).
Likewise, the QRS duration was less specific in cases with left BBBM.
This is consistent with the well-known association between left
BBB and structural heart disease, with its propensity to alter
intraventricular conduction.
Analysis of ECGs in patients taking antiarrhythmic drugs showed
that the QRS duration was >140 ms in most patients, as could be
expected from the pharmacological effect. The second criterion
described by Brugada et al3 tended to be present in
most of these patients. This observation was described by Le Davay et
al.10 They reported the case of a patient treated with
flecainide for atrial fibrillation who was hospitalized because of a
wide QRS tachycardia with an R-to-S interval >100 ms and
with the diagnosis of SVT demonstrated by subsequent endocavitary
electrophysiological studies.
In conclusion, our results highlight the limitations in the specificity
of some of the morphological criteria for the differential diagnosis of
wide QRS tachycardia as derived from the analysis
of tracing with IVCD in sinus rhythm. In contrast, five previously
described criteria have >0.90 specificity in this setting. In view of
the relatively high probability of some of them having a BBB in sinus
rhythm (18 of 70 in the Kremers et al series4 ), this
information may be of particular clinical importance in patients who
are first seen in wide QRS tachycardia and for whom
information about sinus rhythm ECG is lacking.
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Selected Abbreviations and Acronyms
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| BBB |
= |
bundle branch block |
| BBBM |
= |
BBB morphology |
| IVCD |
= |
intraventricular conduction defect |
| SVT |
= |
supraventricular tachycardia |
| VT |
= |
ventricular tachycardia |
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Footnotes
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Reprint requests to Dr Jesús Almendral, Cardiología
(planta 5), Hospital General Gregorio Marañon. Calle
Doctor Esquerdo 46, 28007 Madrid, Spain.
Received October 21, 1996;
revision received June 18, 1997;
accepted June 26, 1997.
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Abstract
Introduction