title: Non-sustained wide complex tachycardia: an underappreciated sign to aid in diagnosis.
abstract: OBJECTIVE
  The electrocardiographic (ECG) signs used to differentiate ventricular tachycardia (VT) from supraventricular tachycardia (SVT) with aberrancy are specific but not highly sensitive. The purpose of this study was to define the utility of an underappreciated form of atrioventricular (AV) dissociation at the onset of tachycardia, a single dissociated P wave, in the differentiation of non-sustained monomorphic wide complex tachycardia (WCT) in hospitalized patients.
  
  
  RESULTS
  We prospectively analysed tracings from 102 consecutive hospitalized patients who had an episode of non-sustained (≥5 beats, <30 s), monomorphic, WCT (≥100 b.p.m.) on telemetry. WCT was classified as VT, SVT with aberrancy, or undifferentiated WCT based on predefined criteria. Of 102 patients with WCT, 3 (3%) had SVT with aberrancy, 43 (42%) had an undifferentiated WCT, and 56 (55%) had VT. ECG evidence of a single dissociated P wave at the onset of tachycardia (i.e. AV dissociation at the onset) was identified in 29 patients (28%) compared with less frequent traditional signs of VT including second-degree ventriculoatrial (VA) block in 18 patients (18%), AV dissociation during tachycardia in 17 patients (17%), fusion beats in 10 patients (10%), and capture beats in 3 patients (3%). On multivariate analysis, only the prematurity index predicted the occurrence of AV dissociation at the onset of the tachycardia (odds ratio 1.239, 95% confidence interval 1.033-1.486, P = 0.021).
  
  
  CONCLUSIONS
  When evaluating WCT in hospitalized patients, a single dissociated P wave at the onset of tachycardia is an easily recognizable diagnostic sign of VT, and is observed more frequently than the other accepted criteria for VT.
authors.affiliation: Division of Cardiology and Department of Medicine, Albany Medical College, Albany Medical Center, 43 New Scotland Avenue, Albany, NY 12208, USA.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Padala
authors.affiliation: Division of Cardiology and Department of Medicine, Albany Medical College, Albany Medical Center, 43 New Scotland Avenue, Albany, NY 12208, USA sidhum@mail.amc.edu.
authors.forename: Mandeep S
authors.initials: MS
authors.lastname: Sidhu
authors.affiliation: Dartmouth-Hitchcock Medical Center, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA.
authors.forename: Jeremiah R
authors.initials: JR
authors.lastname: Brown
authors.affiliation: Department of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Zipursky
authors.affiliation: Division of Cardiology and Department of Medicine, Albany Medical College, Albany Medical Center, 43 New Scotland Avenue, Albany, NY 12208, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Steckman
authors.affiliation: Cardiovascular Consultants of Kansas, Wichita, KS, USA.
authors.forename: Dhaval R
authors.initials: DR
authors.lastname: Parikh
authors.affiliation: Dartmouth-Hitchcock Medical Center, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Greenberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000175:diagnosis*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010808:Physical Examination; D011446:Prospective Studies; D013617:Tachycardia, Supraventricular / Q000175:diagnosis*; D017180:Tachycardia, Ventricular / Q000175:diagnosis*
keywords: Atrioventricular dissociation; Non-sustained wide complex tachycardia; Retrograde ventriculoatrial conduction; Supraventricular tachycardia with aberrancy; Ventricular tachycardia