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  • 1. 1649A New Approach to the DifferentialDiagnosis of a Regular TachycardiaWith a Wide QRS Complex Pedro Brugada, MD; Josep Brugada, MD; Lluis Mont, MD;Joep Smeets, MD; and Erik W. Andries, MDBackground. In the differential diagnosis of a tachycardia with a wide QRS complex (.0.12 second) diagnostic mistakes are frequent. Therefore, we investigated the reasons for failure of presently available criteria, and we identified new, simpler criteria and incorporated them in a stepwise approach that provides better sensitivity and specificity for making a correct diagnosis. Methods and Results. A prospective analysis revealed that current criteria had a poor specificity for the differential diagnosis. The value of fournew criteria incorporated in a stepwise approach was prospectively analyzed in a total of 554 tachycardias with a widened QRS complex (384 ventricular and 170 supraventricular). The sensitivity of the four consecu- tive steps was 0.987, and the specificity was 0.965.Conclusions. Current criteria for the differential diagnosis between supraventricular tachy- cardia with aberrant conduction and ventricular tachycardia are frequently absent or suggest the wrong diagnosis. The absence of an RS complex in all precordial leads is easily recognizable and highly specific for the diagnosis of ventricular tachycardia. When an RS complex is present in one or more precordial leads, an RS interval of more than 100 msec is highly specific for ventricular tachycardia. This new stepwise approach may prevent diagnostic mistakes. (Circulation 1991;83:1649-1659)T he differential diagnosis of tachycardias on thethe reasons for wrong diagnoses are unclear, lack of12-lead electrocardiogram is not merely an knowledge of current criteria for the differential electrocardiographic exercise. When the diagnosis does not seem to be one; rather, such QRS complex during tachycardia has a normal mor-mistakes seem to be the result of the way the criteria phology, axis, and duration, the diagnosis of su- are applied or interpreted.8-10 praventricular tachycardia is easily made. Fre- The purpose of this study was twofold. On the quently, however, supraventricular tachycardias may one hand, we sought the reasons for failure of have an aberrant intraventricular conduction and acurrently available criteria to provide a correct wide (>0.12 second) QRS complex. In this case,diagnosis by prospectively analyzing these criteria differentiating between supraventricular tachycardiain a series of tachycardias with a wide QRS com- with aberrant conduction (SVT) and ventricular tachy- plex. On the other hand, we sought new and simpler cardia (VT) may become difficult.'criteria and incorporated them in a stepwise ap- Even though several criteria have been proposed proach to make the differential diagnosis simpler, to help in the differential diagnosis,2-7 mistakes aremore decisive, and more accurate. nevertheless frequently made.8-10 Not infrequently, these mistakes have led to wrong therapeutic deci-Methods sions with fatal or almost fatal outcomes. AlthoughIn the first part of the study, presently available criteria for differentiating between SVT with aber-From the Cardiovascular Center (P.B., L.M., E.W.A.), Post- graduate School of Cardiology, OLV Hospital, Aalst, Belgium, andrant conduction and VT were prospectively analyzed the Departments of Physiology (J.B.) and Cardiology (J.S.), Uni-in 236 tachycardias with a wide QRS complex. There versity of Limburg, Maastricht, The Netherlands.were 172 VTs and 64 SVTs with aberrant conductionAddress for correspondence: Pedro Brugada, MD, Professor ofwith electrophysiological proven mechanism. Com- Cardiology, Cardiovascular Center, Postgraduate School of Cardi- ology, OLV Hospital, Moorselbaan 164, B-9300, Aalst, Belgium. plete 12-lead electrocardiograms were available forReceived September 5, 1990; revision accepted January 8, 1991. all patients who were not receiving antiarrhythmic

2. 1650Circulation Vol 83, No5 May 1991TABLE 1. Morphology Criteria in This Study for Ventricular Tachycardia Sensitivity SpecificityPredictiveSVTVT SN SP+Value -Value Tachycardia with a right bundle branch block-like QRSLead V,Monophasic R 11/69 39/650.600.84 0.78 0.69tQR or RS1/69 20/650.300.98 0.95 0.60tTriphasic57/696/650.820.91 0.90 0.834 Lead V6R to S ratio 121/69 15/650.300.76 0.58 0.514 Tachycardia with a left bundle branch block-like QRS Lead V, or V2Any of following:*R >30 msec,>60 msec to nadir S, notched S3/24 91/911.0 0.89 0.96* Lead V6QR or QS0/316/350.171.01.00.52*Monophasic R 31/31 29/351.0 0.17 0.51 1.0t Data obtained from References 5 and 6.*Including any Q wave in lead V6. tValues for the diagnosis of VT. *Values for the diagnosis of SVT with aberrant conductior SVT, supraventricular tachycardia; VT, ventricular tach +Value, predictive positive value; -Value, predictive negative value; R to S ratio, ratio of R wave to S vdrugs. Electrocardiograms were analyzed at a paperwhich favors the diagnosis of VT,45 and 4) morphol- speed of 25 mm/sec as usual in clinical practice. ogy criteria favoring the diagnosis of VT when theCurrent criteria analyzed included 1) a left axis of QRS complex had a right2-5,7 or a left bundle branch the QRS complex in the frontal plane, which favorsblock-like6 morphology. the diagnosis of VT,4.5 2) the presence of atrioven-Particularly important during the first part of the tricular dissociation, which favors the diagnosis ofstudy were the recent observations by Kindwall et al.6 VT,2-7 3) a QRS complex longer than 0.14 second,These investigators reported that an interval betweenTABLE 2. Presence of Atrioventricular Dissociation, Left Axis, and Duration of the QRS Complex in 236 Prospectively Analyzed Tachyeardias With a Widened QRS ComplexAV dissociation Left axis QRS> 140 msecn n '1n n % SVT-RB43 00310 717 SVT-LB21 00 1257 838 All SVT 64 00 15231523 VT-RB 9718 19 63657375 VT-LB 75192557766384 All VT 172 37 21 12070 13679 Diagnosis of VT SN 0.210.700.79 SP 1.0 0.760.72 Predictive + value 1.0 0.890.90 Predictive - value 0.320.480.52 QRS complex >0.12 second. AV, atrioventricular; SVT-RB, supraventricular tachycardia with right bundle branch block aberrant conduction; SVT-LB, supraventricular tachycardia with left bundle branch block aberrant conduction; VT-RB, ventricular tachycardia with a right bundle branch block-like QRS complex; VT-LB, ventricular tachycardia with a left bundle branch block-like QRS complex; + value, predictive positive value; - value, predictive negative value. 3. Brugada et al Differential Diagnosis of Tachycardias 1651ABSENCE OF AN RS COMPLEX IN ALL PRECORDIAL LEADS?TABLE 3. Classic Morphology Criteria in 236 Prospectively Ana-lyzed Tachycardias With a Widened QRS ComplexYES 0oMorphology criteria present in leads /T NEXT QUESTION V1,2 andV1,2V6 V6 None nn%n% n % n %R TOS WTERVAL >100 MS IN ONE PRECORDIAL LEAD?SVT-RB 43 35 81 35 8128 6512YES NOSVT-LB 21 18 86 13 6212 572 10VYTXT QUESTIONAll SVT64 53 83 48 7540 6234VT-RB97 81 83 75 7764 6655VT-LB75 63 84 47 6241 5568ATRVENTRICULAR DISSOCIATION?All VT172 144 84 122 71 105 61 116YESNo QRS complex .0.12 second.VTNXT CKESTION SVT-RB, supraventricular tachycardia with right bundle branchblock aberrant conduction; SVT-LB, supraventricular tachycardiawith left bundle branch block aberrant conduction; VT-RB, ven-tricular tachycardia with a right bundle branch block-like QRS MORHLG CRITERIA FOR VT PRESENT BOTH IN PRECORDIAL LEADS Vl-2 AND VS? complex; VT-LB, ventricular tachycardia with a left bundle branchblock-like QRS complex. VT SVT WITH AIBERRANT CONDUCTIO FIGURE 1. Algorithm for diagnosis of a tachycardia with arecordings, such as aortic pressure, were available to widened QRS complex. When an RS complex cannot bethem. The two observers were not asked to give a identified in any precordial lead, the diagnosis of ventriculardiagnosis but were asked 1) to determine whether an tachycardia (VT) is made. If an RS complex is present in oneRS complex was present in at least one precordial or more precordial leads, the longest RS interval is measured.lead, 2) to measure the longest RS interval in any If the RS interval is longer than 100 msec, the diagnosis of VTprecordial lead with an RS complex, 3) to determine is made. If shorter than 100 msec, the next step of thewhether atrioventricular dissociation was present,and 4) to decide whether both leads V1 and V6 algorithm is considered: whether atrioventricular dissociation fulfilled classic criteria for ventricular tachycardia. is present. If present, the diagnosis of VT is made. If absent,The observers were not aware of the diagnosis, and the morphology criteria for VT are analyzed in leads V, andthe four steps were used in the following way: 1) If V6. If both leads fulfill the criteria for VT, the diagnosis of VT the RS complex was not present in at least one is made. If not, the diagnosis of supraventricular tachycardia precordial lead, the diagnosis of VT was noted, and (SVT) with aberrant conduction is made by exclusion of VT. further analysis was stopped. 2) If an RS complex waspresent with an RS interval of more than 100 msec, the onset of the R wave to the deepest part of the S the diagnosis of VT was noted, and analysis was wavein lead V, or V2 of more than 60 msec in a leftstopped. 3) If atrioventricular dissociation was diag- bundle branch block-like wide QRS complex tachy- nosed, the diagnosis of VT was made, and analysis cardia suggested the diagnosis of VT. We hypothe-was stopped. 4) If the tachycardia fulfilled the mor- sized that measurement of the intrinsic deflection inphology criteria for VT in leads V1 and V6, the any unipolar precordial lead with a clear RS complex diagnosis of VT was made. Table 1 summarizes the should be helpful in differentiating between VT andmorphology criteria used. This analysis by the two SVT with aberrant conduction irrespective of the observers was, therefore, a stepwise approac