Electrocardiographic criteria for ventricular tachycardia in wide complex left bundle branch block morphology tachycardias.

Four electrocardiographic criteria for ventricular tachycardia (VT) were proposed and evaluated. These included (1) an R wave in V1 or V2 of greater than 30-ms duration; (2) any Q wave in V6; (3) a duration of greater than 60 ms from the onset of the QRS to the nadir of the S wave in V1 or V2 and (4) notching on the downstroke of the S wave in V1 or V2. The data showed that all 4 criteria had high predictive accuracy (96 to 100%) and specificity (94 to 100%). The relatively low sensitivities of the 4 criteria alone (30 to 64%) might limit their efficacy. Grouped criteria, however, could differentiate VT from supraventricular tachycardias with high sensitivity, specificity and predictive accuracy. The amount of tracings having either electrocardiographic criteria (1) or (2) or (3) or (4) was determined. The proposed combined criteria had a sensitivity of 100%, specificity of 89% and a predictive accuracy of 96%. Left axis deviation alone was of no value in distinguishing VT from supraventricular tachycardia. Characteristic patterns were present for left bundle branch block pattern VT associated with anterior and inferior myocardial infarction. In conclusion, the 12-lead electrocardiogram alone, when systematically analyzed, can be used to accurately diagnose the origin of wide complex tachycardias with left bundle branch block pattern. Attention to these criteria may lead to more rapid and effective therapy.