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ew algorithm using only lead aVR for differential diagnosisf wide QRS complex tachycardiandrás Vereckei, MD,* Gábor Duray, MD,† Gábor Szénási, PhD,‡ Gregory T. Altemose, MD, FHRS,¶
ohn M. Miller, MD, FHRS§
rom the *3rd Department of Medicine, Semmelweis University, Budapest, Hungary, †National Healthcare Center,ardiovascular Center, Budapest, Hungary, ‡EGIS Pharmaceuticals PLC, Budapest, Hungary, ¶Mayo Clinic, Scottsdale,
§
rizona, and Indiana University School of Medicine, Krannert Institute of Cardiology, Indianapolis, Indiana.cv
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ACKGROUND We recently reported an ECG algorithm for differ-ntial diagnosis of regular wide QRS complex tachycardias thatas superior to the Brugada algorithm.
BJECTIVE The purpose of this study was to further simplify thelgorithm by omitting the complicated morphologic criteria andestricting the analysis to lead aVR.
ETHODS In this study, 483 wide QRS complex tachycardias [351entricular tachycardias (VTs), 112 supraventricular tachycardiasSVTs), 20 preexcited tachycardias] from 313 patients with proveniagnoses were prospectively analyzed by two of the authorslinded to the diagnosis. Lead aVR was analyzed for (1) presencef an initial R wave, (2) width of an initial r or q wave �40 ms, (3)otching on the initial downstroke of a predominantly negativeRS complex, and (4) ventricular activation–velocity ratio (vi/vt),he vertical excursion (in millivolts) recorded during the initial (vi)nd terminal (vt) 40 ms of the QRS complex. When any of criteria
wptclwTwacsiqfrtnaphocReceived June 21, 2007; accepted September 17, 2007.)
547-5271/$ -see front matter © 2008 Heart Rhythm Society. All rights reserved
riterion was analyzed. In step 4, vi/vt �1 suggested SVT, andi/vt �1 suggested VT.
ESULTS The accuracy of the new aVR algorithm and our previouslgorithm was superior to that of the Brugada algorithm (P � .002nd P � .007, respectively). The aVR algorithm and our previouslgorithm had greater sensitivity (P �.001 and P � .001, respec-ively) and negative predictive value for diagnosing VT and greaterpecificity (P �.001 and P � .001, respectively) and positive predic-ive value for diagnosing SVT compared with the Brugada criteria.
ONCLUSION The simplified aVR algorithm classified wide QRSomplex tachycardias with the same accuracy as standard criteriand our previous algorithm and was superior to the Brugadalgorithm.
EYWORDS Wide QRS complex tachycardia; Brugada criteria; Ven-ricular tachycardia; Supraventricular tachycardia
Heart Rhythm 2008;5:89–98) © 2008 Heart Rhythm Society. All
to 3 was present, VT was diagnosed; when absent, the next rights reserved.ntroductionespite the publication of numerous algorithms and criteria,
elatively few improvements have been made in the ECGifferential diagnosis of wide QRS complex tachycardiaince the landmark 1978, 1988, and 1991 publications of
ellens et al,1 Kindwall et al,2 and Brugada et al.3 Thus,aking an accurate rapid diagnosis in patients with wideRS complex tachycardia remains a significant clinicalroblem. Using all reported traditional ECG criteria1–14
ay yield an accurate diagnosis in approximately 90% ofide QRS complex tachycardias.5,6,9 However, many of
hese criteria are complicated, or they are not applicable inlarge proportion of cases and thus are not useful in an
rgent setting. Brugada et al3 stated that their algorithm hadigher sensitivity and specificity than the traditional criteria,ut they did not provide a true head-to-head comparison
This manuscript was processed by a guest editor. Address reprintequests and correspondence: Dr. András Vereckei, 3rd Department ofedicine, Semmelweis University, School of Medicine, Budapest,útvölgyi út 4, Hungary 1125. E-mail address: [email protected].
ith other methods used in their study. We recently pro-osed a new simplified four-step decision treelike algorithmo distinguish between regular monomorphic wide QRSomplex tachycardias caused by supraventricular ventricu-ar tachycardia (SVT) and ventricular tachycardia (VT),hich proved to be superior to the Brugada algorithm.15
wo new criteria were incorporated in the recent algorithm,hich required knowledge only of typical bundle branch
nd fascicular block patterns, and eliminated some of theomplicated morphologic criteria used in the final (fourth)tep of the otherwise simple Brugada algorithm. However,n most cases, application of our recent algorithm re-uired more time than did the Brugada algorithm. There-ore, we sought to further simplify and improve ourecent algorithm. To this end, another four-step, decisionreelike algorithm was devised that completely elimi-ated the complicated morphologic criteria and limitednalysis to a single lead (aVR) while preserving our tworevious new criteria. Lead aVR was chosen because weypothesized that it might be more sensitive than thether leads in differentiating wide QRS complex tachy-
ardias because, in normal sinus rhythm and SVT, the. doi:10.1016/j.hrthm.2007.09.020
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90 Heart Rhythm, Vol 5, No 1, January 2008
entricular activation wavefront proceeds in a directionway from aVR, typically yielding a QS complex in aVR.n the present study, the overall test accuracy, sensitivity,pecificity, and predictive values of the new aVR algo-ithm were compared with those of our previous algo-ithm as well as the Brugada algorithm.
ethodsdifferent set of patients from that used to test the already
stablished algorithm was used to devise the algorithm. Toevise an optimal algorithm, we retrospectively used 103ide QRS complex tachycardias available from the data-ase of Indiana University. The recordings were obtainedrom 69 patients with proven electrophysiologic diagnosesn whom wide QRS complex tachycardia was induced dur-ng electrophysiologic study. To test the established algo-ithm, 483 regular wide QRS complex tachycardia ECGs351 VTs, 112 SVTs, 20 preexcited tachycardias) recordedrom 313 consecutive patients were prospectively analyzedy two of the authors (observer 1 � AV; observer 2 � GD)linded to the electrophysiologic diagnosis and the patients’linical data. ECGs were obtained from June 1998 to June005 at Indiana University during electrophysiologic stud-es at which the arrhythmia diagnosis was proven. In thistudy, 453 of the 483 wide QRS complex tachycardia ECGssed were identical to those analyzed in our previoustudy.15 Wide QRS complex tachycardia tracings from pa-ients with preexisting bundle branch block or idiopathicTs and/or from patients taking either class I antiarrhyth-ic drugs or amiodarone (144, 38, and 158 tracings, respec-
ively) were also included in this study. The 38 idiopathicTs analyzed consisted of 11 fascicular VTs, 14 right ven-
ricular outflow tract VTs, and 13 VTs of other types. Annformed consent exemption was obtained from the Indiananiversity Institutional Review Board for analysis of ae-identified dataset. The observers were given complete2-lead standard ECGs recorded during tachycardia fornalysis. The ECG leads were in standard positions, withhe possible exception of leads V3 to V5, which often wereisplaced one interspace due to the placement of defibrilla-or pads. This exception was noted to not make muchifference compared with ECGs obtained using standardhest lead location. Wide QRS complex tachycardia wasefined as a rhythm with a rate �100/min and QRS duration120 ms. Only monomorphic wide QRS complex tachy-
ardias were analyzed using the following criteria in leadVR: (1) presence of an initial R wave, (2) presence of annitial r or q wave with width �40 ms, (3) notching on theescending limb of a negative onset, predominantly nega-ive QRS complex, and (4) assessment of initial (vi) anderminal (vt) ventricular activation velocity ratio (vi/vt) by
easuring the vertical excursion (in millivolts) recorded onhe ECG during the initial (vi) and terminal 40 ms (vt) of theRS complex. When either the initial or terminal 40 ms of
he QRS complex displayed both positive and negativeeflections, the sum of their absolute values (disregarding
olarity) was used as the values of vi and vt. Validation of ahe vi/vt criterion was described in our previous report.15
ecause three channels were recorded simultaneously onhe ECG tracings, the onset and end of the QRS wereefined by the earliest and latest ventricular depolariza-ion, respectively, among the three simultaneously re-orded augmented limb leads (aVR, aVL, aVF). Weypothesized that the presence of an initial dominant Rave (such as R or RS complex, but not rS complex) or
n initial r or q wave �40 ms, or a notch on the down-troke of a negative onset and predominantly negativeRS in lead aVR, suggested VT. We also hypothesized
hat vi/vt �1 suggested SVT and vi/vt �1 indicated VT.he four criteria of the new aVR algorithm were orga-ized in a stepwise, decision-tree format similar to that ofhe Brugada algorithm and our previous algorithm. Whenny of the first three criteria of the algorithm was met, aiagnosis of VT was made, and the analysis was stoppedt that step. In the last step, vi/vt �1 was considerediagnostic for VT, and vi/vt �1 was considered diagnos-ic for SVT. Figure 1 shows the new aVR algorithm, ourrevious algorithm, and the Brugada algorithm. and Fig-res 2, 3, and 4 show examples of how the new aVRlgorithm was applied.
tatistical analysisccurrence of true as well as false-positive and negative
esults, as well as sensitivity and specificity, were comparedetween two algorithms by first constructing 2�2 cross-ables demonstrating where the two algorithms agreed orisagreed. Thereafter, the nonparametric McNemar testas used to compare two related proportions and deter-ine which algorithm was better. SPSS for Windows
version 13, SPSS Inc., Chicago, IL, USA) was used fortatistical analysis. P �.05 value was considered signif-cant. The method described was not suitable for com-arison of predictive values because the denominators forhe two algorithms differ (unlike specificity and sensitiv-ty, in which the denominators are the same). Lacking anntirely appropriate statistical method for comparing pre-ictive values, these values are presented simply with5% confidence intervals (CI) without statistical compar-son. A significant between-groups difference in algo-ithms is indicated by disjoint (nonoverlapping) confi-ence intervals. Some patients are present in the datasetore than once (several VTs with different morphologyere induced in some patients, whereas a few patientsad wide QRS complex tachycardias due to both SVTnd VT during the same electrophysiologic study). Be-ause these episodes behaved as independent unrelatedvents, they were analyzed as different wide QRS com-lex tachycardia tracings in the study.
The � statistic was used to quantify overall interobservergreement using the SAS statistical software package (SAS/TAT Software Release 6.12, SAS Institute). Overall inter-bserver agreement was defined as good if � �0.6, moder-
te if 0.6���0.4, and poor if � �0.4.
Fs
91Vereckei et al New Lead aVR Wide QRS Tachycardia Algorithm
igure 1 The new aVR algorithm, our previous algorithm, and the Brugada algorithm. BBB � bundle branch block; FB � fascicular block; SVT �
upraventricular tachycardia; VT � ventricular tachycardia.
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92 Heart Rhythm, Vol 5, No 1, January 2008
esultsatient characteristicshe patient groups differed in that the preexcited tachycar-ia and SVT groups had younger patients, more femaleatients, fewer patients with a history of prior myocardialnfarction or dilated cardiomyopathy, and far more patientsithout structural heart disease than the VT group (Table 1).
verall test accuracyesults are given in Table 2. The new aVR algorithm wasot applicable in only 1 (0.2%) of 483 wide QRS complexachycardias because of an isoelectric lead aVR in thisracing. In order to compare the results in an identicalample size, this wide QRS complex tachycardia was ex-luded from the analysis. The new aVR algorithm correctlylassified 441 of 482 wide QRS complex tachycardias91.5% overall test accuracy), which was similar to ourrevious algorithm [437/482 wide QRS complex tachycar-ias (90.7% overall test accuracy)]. Both were superiorP � .002 and P � .007, respectively) to the Brugadalgorithm [412/482 (85.5% overall test accuracy)]. Thereas no difference in the overall test accuracy of the new
VR algorithm and our previous algorithm. The first stepinitial R wave in aVR) correctly diagnosed VT in 98.6% ofases in which it was positive, whereas a correct diagnosisas made by the second, third, and fourth criteria in 87.8%,6.4%, and 89.3% of applicable cases, respectively. Theverall test accuracy of the first Brugada criterion wasignificantly (P � .0308) lower than that of the first criterion
igure 2 Examples of the positivity of the first three steps of the new af the first three steps of the new aVR algorithm was positive (i.e., suggesteecorded leads aVR, aVL, and aVF are shown from each 12-lead ECG. Lerossing point of the vertical line with the contour of the last QRS denoteave width of 70 ms; therefore, the second step of the algorithm suggesegative QRS; thus, VT is diagnosed in the third step. The crossing points ond end of the QRS.
f the new aVR algorithm (93.3% vs 98.6%) as well as that o
f the fourth Brugada criterion (71% vs 89.3% for the newVR algorithm and 82.8% for our previous algorithm; P �005 and P � .0136, respectively) compared with that of the
i/vt criterion in the fourth step of the new aVR and ourrevious algorithms. The second criterion of our previouslgorithm had a significantly (P � .0363) higher overall testccuracy than did the second Brugada criterion (97.7% vs2.4%). Thus, the superiority of the two new criteria (initialwave in lead aVR and vi/vt index) to their counterparts in
he same ordinal rank in the Brugada algorithm is respon-ible for the superior overall test accuracy of the new aVRnd our previous algorithms compared with that of therugada algorithm.
We also evaluated a modified five-step aVR algorithm, inhich the first step was AV dissociation and the next four
teps were identical to the new aVR algorithm. This yieldedhe correct diagnosis in only one other case, when comparedo the four-step aVR algorithm (442/482 vs 441/482 cases).
Fifteen wide QRS complex tachycardia episodes wereisclassified by both the new aVR and Brugada algorithms.hese episodes were mostly SVTs misdiagnosed as VT
12/15(80%)], and two thirds [10/15 (67%)] of them wereresent with a right bundle branch block pattern. No otherommon characteristics of the ECGs misclassified by bothhe new aVR and Brugada algorithms were identified. Thewo observers produced very similar results. Interobserverariability was nonsignificant, as was the difference be-ween the misclassified ECGs using all three algorithmsetween the two observers. Therefore, only results from
orithm. Three different wide QRS complex tachycardia ECGs where onenosis of ventricular tachycardia [VT]) are shown. Only the simultaneouslynitial R wave is present in lead aVR; thus, the first step suggests VT. Thenset of the QRS. Middle: An rS complex is seen in lead aVR, with an rRight: Notch on the downstroke of a negative onset and predominantlyo vertical lines with the contour of the sixth QRS complex mark the onset
VR algd a diagft: An is the ots VT.f the tw
bserver 1 are published and used for analysis. Figure 5
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93Vereckei et al New Lead aVR Wide QRS Tachycardia Algorithm
hows the numbers of VT and SVT true and false-positiveiagnoses made in each step of the new aVR algorithm.
Because the second criterion of the aVR algorithm mighte affected by antiarrhythmic drug treatment, the secondriterion was also evaluated separately in wide QRS com-lex tachycardia tracings recorded from patients with andithout antiarrhythmic medication. From a total of 158ide QRS complex tachycardia tracings recorded from pa-
ients receiving antiarrhythmic drug treatment in this study,he first criterion of the aVR algorithm was positive in 75ide QRS complex tachycardia tracings; therefore, 83 trac-
ngs remained for application of the second criterion.mong wide QRS complex tachycardias obtained fromatients taking antiarrhythmic medication, the second crite-ion was positive in 24 (29%) of 83. In all 24 cases theriterion was true positive; thus, antiarrhythmic drug treat-ent did not affect the performance of the second criterion.ll nine false-positive cases (Figure 5) during application of
he second criterion occurred in wide QRS complex tachy-ardias obtained from patients without antiarrhythmic drugreatment, simply because false positivity of the second
igure 3 Use of vi/vt criterion in the fourth step of the new aVR algoritn lead aVR show the onset and end of the QRS complex in lead aVR. Tharked by small crosses. Left: During the initial 40 ms of the QRS, the is of the QRS, the impulse traveled vertically 0.6 mV; therefore, vt � 0.
.4 and vt � 0.2, determined the same way as in the left panel; thus, vi/v
riterion means that the patient had SVT, and the great s
ajority (96%) of SVT patients did not receive antiarrhyth-ic medication. Our new aVR and previous algorithms, asell as that of the Brugada algorithm and traditional mor-hologic ECG criteria, are unable to reliably differentiateTs from preexcited tachycardias in most wide QRS com-lex tachycardia cases. One possible exception may be theresence of an initial R wave in lead aVR, when using theew aVR algorithm, which seems to exclude preexcitedachycardia (with possible exception of the rare preexcitedachycardias using epicardial left-sided paraseptal or infero-osterior bypass tracts). In fact, none of our 20 preexcitedachycardias had an initial R wave in lead aVR; however,his suggestion requires further testing (for further discus-ion, see Vereckei et al15). Thus, the final diagnosis of VTsing the new aVR algorithm also included preexcitedachycardias.
ensitivity, specificity, and predictive valuesecause only two final diagnoses (VT or SVT) were pos-
ible with the algorithms used, the specificity and positiveredictive value for VT diagnosis were the same as the
oth panels, the crossing points of the vertical lines with the QRS contouring points and initial and terminal 40 ms of the chosen QRS complex aretraveled vertically 0.15 mV; therefore, vi � 0.15. During the terminal 40, vi/vt�1 yields a diagnosis of ventricular tachycardia (VT). Right: vi �gests a diagnosis of supraventricular tachycardia (SVT).
hm. In be crossmpulse6. Thus
ensitivity and negative predictive value for SVT diagnosis
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94 Heart Rhythm, Vol 5, No 1, January 2008
respectively). Inversely, the sensitivity and negative pre-ictive value for VT diagnosis were the same as the spec-ficity and positive predictive value for SVT diagnosis,espectively. For this reason, only data for VT diagnosis areeported, which can be applied accordingly for the appro-
igure 4 Representative example of wide QRS complex tachycardiaue to supraventricular tachycardia is shown when the initial as well as theerminal 40 ms of the QRS complex in lead aVR displayed both positivend negative deflections and the sum of their absolute values (disregardingolarity) were used as the values of vi and vt. The crossing points of theertical lines with the QRS contour in lead aVR show the onset and end ofhe QRS complex in lead aVR. The crossing points and initial and terminal0 ms of the chosen QRS complex are marked by crosses. The points of theRS where the polarity of the QRS is changing within the initial and
erminal 40 ms are marked by arrows. In the initial 40 ms from the onsetf the QRS to the nadir denoted by arrow, the impulse traveled 0.825 mVn vertical direction. From the nadir to the second cross, marking 40s from the onset of the QRS, the impulse traveled 1.025 mV; thus, vi �
.825 � 1.025 � 1.85 mV. From the end of the QRS to the turning pointf polarity marked by the other arrow, the impulse traveled 0.325 mV.rom the turning point to the point located 40 ms from the end of the QRSenoted by the third cross from the onset of the QRS, the impulse traveled.125 mV. Thus, vt � 0.325 � 0.125 � 0.45 mV, resulting in vi/vt �1,uggesting supraventricular tachycardia.
able 1 Clinical characteristics of the patients
Supraventricu(n � 112)
ge (yr; mean � SD) 44 � 20emale/male (%) 44/56istoryPostmyocardial infarction (%) 4Dilated cardiomyopathy (%) 1
No structural heart disease (idiopathic) (%) 93riate parameters in SVT diagnosis (Table 3). The new aVRlgorithm as well as our previous algorithm had greaterensitivity for VT diagnosis than did the Brugada algorithm96.5% and 95.7% vs 89.2%, P �.001 and P � .001,espectively). Likewise, the negative predictive values ofhe new aVR and our previous algorithms were better thanhe Brugada algorithm (86.6% and 83.8% vs 67.2%). The
i/vt criterion applied in the fourth step of the new aVR andur previous algorithms had a significantly greater sensitiv-ty for VT diagnosis (90.7% and 69.8%) compared with theourth Brugada criterion (45.2%; P �.001 and P � .007,espectively) as well as negative predictive value for VTiagnosis (87.5% and 83.8% vs 67.2%). The sensitivity forT diagnosis of the vi/vt criterion applied in the fourth stepf the new aVR algorithm was superior to that of the vi/vt
riterion applied in the fourth step of our previous algorithm90.7% vs 69.8%, respectively, P � .005). Compared withhe first Brugada criterion, the first criterion of the new aVRlgorithm had greater sensitivity (38.9% vs 22.4%,�.001) and specificity (98.2% vs 94.6%, P � .0088; these
ignificance data are not shown in Table 3). When allriteria were combined, there was no difference in the sen-itivity, specificity, and predictive values between the newVR and our previous algorithms.
iscussionajor findingshe new aVR algorithm is based solely on the principle ofifferences in the direction and velocity of the initial anderminal ventricular activation during wide QRS complexachycardia due to VT and SVT. Our study shows that bothur new aVR algorithm and the previous algorithm devisedor differential diagnosis of wide QRS complex tachycar-ias have superior overall test accuracy and greater sensi-ivity and negative predictive value in VT diagnosis com-ared with the Brugada algorithm. This superiority isainly due to the two new incorporated criteria. There was
o significant difference in any studied parameter betweenhe greatly simplified new aVR and our previous algorithm.he overall test accuracy of the new aVR and our previouslgorithm was on par with the use of all published, difficult-o-recall traditional ECG criteria.6,9
ew concepts in the aVR algorithmlthough the new aVR algorithm does not contain any
undamentally new criteria, it is based on three novel con-
hycardia Ventricular tachycardia(n � 350)
Preexcited tachycardia(n � 20)
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95Vereckei et al New Lead aVR Wide QRS Tachycardia Algorithm
epts: (1) selection of lead aVR exclusively for differentialiagnosis of wide QRS complex tachycardias; (2) classifi-ation of VTs into two main groups—(a) VTs arising from
able 2 Percentage of correct diagnoses (test accuracy) made
riterion
irst new aVR algorithm criterion (initial R wave)econd new aVR algorithm criterion (r or q wave �40 ms)hird new aVR algorithm criterion (notch)ourth new aVR algorithm criterion (vi/vt)ew aVR algorithm, all criteriairst criterion of our previous algorithm (AV dissociation)econd criterion of our previous algorithm (initial R wave in aVR)hird criterion of our previous algorithm (bundle branch block, faourth criterion of our previous algorithm (vi/vt)ur previous algorithm, all criteriairst Brugada criterion (absence of RS)econd Brugada criterion (RS �100 ms)hird Brugada criterion (AV dissociation)ourth Brugada criterion (morphology in V1,2 and V6)rugada algorithm, all criteria
Numbers represent number of correct diagnoses/total number of tracinntervals)]. The overall (both for ventricular tachycardia [VT] and ventricuur previous algorithm, and the Brugada algorithm was compared statisticaompared with that of their counterparts in the same ordinal rank in theP �.05, **P �.01, ***P �.001 vs all criteria of the new aVR algorithmP �.05, ##P �.01, ###P �.001 vs all criteria of our previous algorithm.P �.05, §§P �.01, §§§P �.001 vs the Brugada criterion at the same stP �.01 for the second criterion of our previous vs the second criterion
igure 5 Numbers of ventricular tachycardia (VT) and supraventricularachycardia (SVT) and true and false-positive diagnoses made in each step
sf the new aVR algorithm. WCT � wide QRS complex tachycardia.
he inferior or apical region of the ventricles yielding annitial R wave in lead aVR, and (b) VTs arising fromther regions and lacking an initial R wave in aVR butith slowing of the initial part of the QRS complex (this
s in contrast to SVTs that show more rapid initial QRSorces); and (3) elimination of the AV dissociation cri-erion and complex morphologic criteria used by all priorlgorithms and traditional criteria.
hoice of lead aVR and classification of VTsnto two main formsuring SVT with bundle branch block, both the initial
apid septal activation (which can be either left to right oright to left) and the later main ventricular activationavefront proceed in a direction away from lead aVR,ielding a negative QRS complex in lead aVR (Figure 5).n exception to this generalization occurs in the presencef an inferior myocardial infarction. An initial r wave (rSomplex) may be seen in lead aVR during normal sinushythm or SVT due to loss of initial inferiorly directedorces. An rS complex also may be present as a normalariant in lead aVR, but with R/S �1. With these con-iderations, an initial dominant R wave should not beresent in SVT with bundle branch block.16,17
Because an initial dominant R wave in aVR is incom-atible with SVT, its presence suggests VT, typicallyrising from the inferior or apical region of the ventricles.or this reason, lead aVR is more useful than other leads
n distinguishing SVT from VT (Figure 6). We alsoypothesized that lead aVR is more sensitive than othereads in detecting VTs originating from sites other thanhe inferior or apical wall of the ventricles, but not
erent ECG criteria*,***,#,###,§§§
Correct diagnosis
144/146 [98.6§ (96.7–100.5)]65/74 [87.8 (80.4–95.3)]32/37 [86.5 (75.5–97.5)]
201/225 [89.3§§ (85.3–93.4)]441/482 [91.5 (89–94)]
43/43 [100 (100–100)]130/133 [97.7§,� (95.2–100.3)]
r block criterion) 145/162 [89.5 (84.8–94.2)]120/145 [82.8§ (76.6–88.9)]437/482 [90.7 (88.1–93.3)]
83/89 [93.3 (88–98.5)]208/225 [92.4 (89–95.9)]
6/6 [100 (100–100)]115/162 [71 (64–78)]412/482 [85.5**,## (82.3–88.6)]
stigated with the criterion [cpercentage � test accuracy (95% confidenceycardia [SVT] diagnoses) test accuracy of all four criteria of the new aVR,addition, the overall test accuracy of each step of all three algorithms waslgorithm separately.
e Brugada algorithm.new aVR algorithm.
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howing an initial R wave in aVR. We hypothesized that
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96 Heart Rhythm, Vol 5, No 1, January 2008
hese VTs (except for VT arising from the most basalites of the interventricular septum or free wall) shouldield a slow, initial upward vector component of variableize pointing toward lead aVR (absent in SVT), even ifhe main vector in these VTs points downward, yielding
totally or predominantly negative QRS in lead aVRFigure 6). Another critical difference between VT andVT, which is also the rationale of vi/vt criterion, is that
n SVT with bundle branch block the initial activation isapid, and the width of the QRS is caused by delay in theid to terminal part of the QRS. In contrast, during VT,
he initial ventricular activation is as slow or slower thanhe terminal activation due to an initial slower muscle-o-muscle spread of activation until the impulse reacheshe His–Purkinje system, after which the rest of theentricular muscle is more rapidly activated.15 Thus, inT without an initial R wave in lead aVR, the initial partf the QRS in lead aVR should be less steep (“slow”) due tohe slower initial ventricular activation having an initialpward vector component, which may be manifested as annitial r or q wave with width �40 ms, a notch on the
able 3 Sensitivity, specificity, and positive and negative predRS complex tachycardia*,**�,���,c,cc,d,ddd,ee
riterion Sensitivity VT diagnos
irst new aVR algorithm criterion (initialR wave)
38.9 (34–43.9
econd new aVR algorithm criterion (r orq wave �40 ms)
28.8 (22.9–34
hird new aVR algorithm criterion (notch) 19.9 (13.7–26ourth new aVR algorithm criterion (vi/vt) 90.7 (85.7–95ew aVR algorithm, all criteria 96.5 (94.6–98irst criterion previous algorithm (AVdissociation)
11.6 (8.4–14.
econd criterion previous algorithm(initial R in aVR)
39.6 (34.3–44
hird criterion previous algorithm (bundlebranch block, fascicular block criterion)
73.2 (67.1–79
ourth criterion previous algorithm (vi/vt) 69.8e(57.5–82revious algorithm, all criteria 95.7 (93.6–97irst Brugada criterion (absence of RS) 22.4 (18.2–26econd Brugada criterion (RS �100 ms) 72.5 (67.3–77hird Brugada criterion (AV dissociation) 7.6 (34.3–44ourth Brugada criterion (morphology inV1,2 and V6)
45.2ccc,dd (33.8–56
rugada algorithm, all criteria 89.2***,�� (86–92.4
Because only two final diagnoses (ventricular tachycardia [VT] or supecificity and positive predictive value (PPV) for VT diagnosis were therespectively). Inversely, the sensitivity and NPV for VT diagnosis were thhe sensitivity, specificity, and predictive values for VT diagnosis are sonfidence intervals. The sensitivity, specificity, and predictive values of aere compared statistically; those of the fourth step of all three algorithmsalues (#vs all criteria of the new aVR algorithm, ¶vs all criteria of our prfourth Brugada criterion vs fourth step of our previous algorithm) is ind
For sensitivity and specificity: *P �.05,**P �.01,***P �.001 vs all cP �.05, ��P �.01, ���P �.001 vs all criteria of our previous alg
P �.05, ccP �.01, cccP �.001 for the fourth Brugada criterion vs the fouP �.05, ddP �.01, dddP �.001 for the fourth Brugada criterion vs the foeP �.01 for the fourth step of the new aVR algorithm vs the fourth step
ownstroke of the QRS, or a slower ventricular activation h
uring the initial 40 ms than during the terminal 40 ms ofhe QRS (vi/vt �1) in lead aVR. In contrast, in SVT withundle branch block, the initial part of the QRS in lead aVRs steeper (“fast”) due to the invariably rapid septal activa-ion going away from lead aVR, resulting in a narrow (�40s) initial r or q wave and vi/vt �1.
mission of AV dissociation and complexorphologic criteriahe AV dissociation criterion was omitted because it didot affect the overall test accuracy of the new aVR algo-ithm. However, because the AV dissociation criterion is00% specific (but not sensitive) and is universally agreedo be a useful criterion in the differential diagnosis of wideRS complex tachycardias, it still can used in the first step
ogether with the four-step aVR algorithm as a five-steplgorithm. Complex morphologic criteria were similarlymitted. Figure 7 shows representative examples of VTsnd SVTs recorded from patients showing common patternsbserved in lead aVR that are consistent with the outlined
values of different ECG criteria for differential diagnosis of wide
pecificity VT diagnosis PPV VT diagnosis NPV VT diagnosis
8.2 (95.8–100.7) 98.6 (96.7–100.5) 32.7 (27.7–37.8)
1.8 (86.7–96.9) 87.8 (80.4–95.3) 38.5 (32.7–44.4)
95 (90.8–99.8) 86.5 (75.5–97.5) 42.7 (36.2–49.1)7.5 (80.9–94.1) 90.7 (85.7–95.7) 87.5 (80.9–94.1)75 (82.9–96) 92.7 (90.1–95.3) 86.6 (79.8–93.4)
100 (100–100) 100 (100–100) 25.5 (21.4–29.6)
7.3 (94.3–100.3) 97.7 (95.2–100.3) 35.5 (30.2–40.9)
4.4 (77.6–91.2) 89.5 (84.8–94.2) 63.4 (55.6–71.3)
0.2 (84.1–96.3) 80.4 (69–91.9) 83.8 (76.6–91.1)4.1 (66–82.2) 92.4 (89.8–95.1) 83.8 (76.6–91.1)4.6 (90.5–98.8) 93.3 (88–98.5) 27 (22.6–31.4)84 (77–90.9) 92.4 (89–95.9) 53 (45.4–60.5)
100 (100–100) 100 (100–100) 59.2 (52–66.4)2.1 (86.5–97.7) 82.5 (70.7–94.3) 67.2a,b (58.9–75.5)
3.2 (65–81.4) 91.7 (88.8–94.5) 67.2#,¶ (58.9–75.5)
tricular ventricular [SVT]) were possible with the algorithms used, thes the sensitivity and negative predictive value (NPV) for SVT diagnosisas the specificity and PPV for SVT diagnosis, respectively. Therefore, onlyumbers represent percentage values; numbers in parentheses are 95%
riteria of the new aVR, our previous algorithm, and the Brugada algorithmompared separately. A significant between-groups difference in predictivelgorithm, afourth Brugada criterion vs fourth step of new aVR algorithm,nly by disjoint (nonoverlapping) 95% confidence intervals.of the new aVR algorithm..p of the new aVR algorithm.p of our previous algorithm.previous algorithm.
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97Vereckei et al New Lead aVR Wide QRS Tachycardia Algorithm
dvantages and limitations of the newVR algorithm
dvantageshe new aVR algorithm is well suited for emergency situ-tions (e.g., patient presenting with wide QRS complexachycardia) because the algorithm is accurate, reasonablyast, and easy due to the total elimination of complicatedraditional morphologic criteria and the simple requiremento evaluate only lead aVR. Although the actual time neededor application of the three algorithms was not measured inhe study (which is a limitation of the study), the definitempression of both observers 1 and 2 was that application ofhe new aVR algorithm was less time consuming than thatf our previous algorithm and approximately as fast as thatf the Brugada algorithm.
tudy limitationshe limitations of the new aVR algorithm derive partly
rom conditions that may influence vi/vt. These conditionsre anteroseptal myocardial infarction, scar at a late acti-ated ventricular site, fascicular VT, and VT exit site closeo the His–Purkinje system (for detailed discussion, seeereckei et al15). Our previous algorithm was inherently
igure 6 Explanation for ECG patterns in lead aVR with differentauses of wide QRS complex tachycardia. In each example, left and rightentricles are depicted with corresponding pattern in aVR. Solid lines withrrows represent initial rapid vectors. Wavy lines and arrows signifylower impulse propagation. In the box, right bundle branch block (RBBB)nd left bundle branch block (LBBB) aberration patterns are shown. Initialapid septal activation is followed by slower activation of the “blocked”entricle. Figures outside the box show actual aVR patterns during ven-ricular tachycardias (VTs) arising from (clockwise from top right): leftentricular apex; basal lateral left ventricle; midinferior wall; basal inferiorall; basal septum; and right ventricle (RV). VTs arising from near theentricular apex or inferior or lateral ventricular wall are causing an initialwave in lead aVR. VTs arising from other sites have a common feature.
hey result in a predominantly negative resultant main ventricular activa-ion vector that yields a totally or predominantly negative QRS complex inead aVR, with either slowing or widening of the initial part or notching onhe downstroke of the QRS due to an initial upward vector componentnd/or a slower muscle to muscle spread of activation. SVT � supraven-ricular tachycardia.
nable to recognize bundle branch reentry VT, fascicular Q
T, and SVT involving an atriofascicular accessory path-ay that are associated with typical bundle branch blockattern indistinguishable from SVT with bundle branchlock,3,4,8,18 unless AV dissociation was present in the firstwo arrhythmias. Because these rhythm disorders mightive rise to an initial upward vector component, the newVR algorithm might be able to correctly classify bundleranch reentry and fascicular VT as VT; however, thisossibility requires further testing. Subgroup analysis inves-igating how preexistent bundle branch block, class I and IIIntiarrhythmic drug treatment, and idiopathic VT influ-nced the diagnostic accuracy of our previous and Brugadalgorithms was performed in our previous study.15 Becausehe wide QRS complex tachycardia ECGs analyzed in thistudy are almost identical to those used in the previoustudy, no similar subgroup analysis was performed in ordero avoid duplication of results. Although Brugada et al2
elieved that their algorithm was superior to the traditionalriteria, other authors,3,8,19,20 similar to us, reported lowerensitivity and much lower specificity of the Brugada algo-ithm than originally reported,2 although they still found therugada algorithm useful. Thus, the superiority of the newVR and our previous algorithm to the Brugada algorithmoes not mean that our two algorithms should be used to thexclusion of other methods for evaluation of wide QRSomplex tachycardia.
Another limitation of our study is the relatively smallumber of cases of VT occurring in the absence of structuraleart disease. These VTs often are more narrow than thosen patients with myocardial disease and more easily con-used with SVT when applying other differentiating algo-ithms. It is possible that the new aVR algorithm is not asuccessful in this group as among VTs related to structuraleart disease.
The inability of the aVR algorithm to differentiate pre-xcited tachycardias from VTs (with the possible exceptionf the presence of initial R wave in lead aVR) is a limitationf the algorithm. However, the traditional ECG criteria,
igure 7 Representative examples of the most common lead aVR ECGatterns taken from real tracings recorded from patients with wide QRSomplex tachycardias due to ventricular tachycardia (VT) and supraven-ricular tachycardia (SVT) superimposed on a grid (small box � 40 ms).escriptions are given to the left of each QRS complex. Patterns seen inT cases are shown on the left; SVT examples are at right. “Notched,”
slow,” and “rapid” refer to the type of descent of the initial portion of the
RS complex from onset to nadir.
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98 Heart Rhythm, Vol 5, No 1, January 2008
ith the exception of the presence of AV dissociation andther criteria suggested by Antunes et al,21 which are infre-uently present, also are unable to differentiate VTs fromreexcited tachycardias. Preexcited tachycardias constituteuch a small proportion of wide QRS complex tachycardiasn all series (4.1 % in our study) that the inability to distin-uish them from VTs is relatively insignificant.
onclusionur new aVR algorithm proved to be a reasonably rapid,
asy, and accurate means for obtaining the correct diagnosisn the differential diagnosis of wide QRS complex tachy-ardias. We found the algorithm be superior to the relativelyimple Brugada algorithm and at least as accurate as theore complicated traditional morphologic criteria. There-
ore, our new algorithm seems to be well suited for appli-ation in typically stressful clinical circumstances in whichide QRS complex tachycardia is encountered. However,sing any published criteria or algorithm, the true cause ofegular wide QRS complex tachycardias still is misdiag-osed in up to 10% of cases. A reasonable course of actions to treat all sustained regular wide QRS complex tachy-ardias as VT unless the diagnosis of SVT can be definitelystablished. It is far better to be wrong with a few cases ofVT treated as VT than the reverse situation, because treat-
ng a VT as SVT may result in potentially disastrous con-equences (e.g., intravenous verapamil injection causingevere hypotension and/or VT acceleration and ventricularbrillation4,22,23).
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