2 exceptions that do not fit criteria for VT based on the standard recognition patterns:
LVOT VT
Fascicular VT

Bizarre complex
LVOT VT – pattern recognition
Fascicular have a RBBB but sometimes do not have a negative S wave in V6
FAVORS VT

RBBB
V1 R wave
V1 Rsr' (R>r')
V1 qR
V6 r/S < 1
RBBB > 140 ms
FAVORS VT

LBBB
V1 r> 30 ms
V1 QS
V1 Notched S
V6 q
LBBB > 160 ms
FAVORS VT

Negative Concordance  LV apex
Positive Concordance Basal VT (or L AP along MA)
R/S in any precordial > 100 ms
Negative in V4-V6 = apical VT (AP doesn't insert on apex)
QR in > 1 lead (V2-V6)
V>A
FAVORS VT

Right Superior Axis (NW)
LBBB + RAD
Capture
Fusion
Marching P waves
(exception: AVNRT with aberration and JA block - JT with aberration and JA
block - Nodofascicular AP with JA block)
Early return of sinus beat post VT (< sinus CL)
EPS for VT confirmation

A Pacing => Capture - Fusion = VT
A Pacing accelerates V to the pacing rate without a change in the morphology =>
                                                                                   SVT with aberrancy
                                                                                   Preexcitation (antidromic)
                                                                                   BBRT
AVJR APD advances V without change in morphology => preexcitation
AVJR APD terminates WCT with AVB => excludes VT
 
VT
SVT
AV Dissociation
50%
Never
QRS Duration
> 140 ms
< 140 ms
Precordial Concordance
+
-
If RBBB Configuration
Lead V1: Rsr' R>r'
Lead V6: Monophasic QRS
Axis < -30
Lead V1: rsR' R'>r
Lead V6: triphasic QRS common
Axis > -30
If LBBB Configuration:
Lead V1
Wide R >40 ms
Narrow R
ECG CRITERIA FOR DISTINGUISHING SVT AND VT
TYPICAL RBBB
-Terminal broad S in I
-rsR' in V1 or notched monophasic R with notching on ascending limb of R wave
-RS complex in V6 with R/S ratio > 1

TYPICAL LBBB
-Monophasic R in I, V6 without q
-Dominant S with rapid, un-notched descent in V1 (rS or QS with onset of QRS to Nadir < 70 ms)

Sensitivity ~90%, Specificity ~75%
PITFALLS
-Fasicular VT (RBBB and LAFB or LPFB)
-Preexcited VT
-BBR might be falsely diagnosed as SVT with aberrancy (unless VA dissociation)
Varosy presentation on SVT vs VT