Abstract 16794: Electrocardiographic Differentiation of Fascicular Ventricular Tachycardia From Atrial Flutter With Right Bundle Branch Block Aberrant Conduction
Introduction: Atrial fibrillation often converts to atrial flutter (AFL) during management with class IC antiarrhythmic drugs. Differentiation of AFL with right bundle branch block (RBBB) pattern from fascicular ventricular tachycardia (VT) is difficult when R/S ratio in V6 is below 1.0. We sought to investigate the electrocardiographic criterion for distinguishing these arrhythmias.
Method: We studied 32 consecutive patients (mean age 40.7±15.8 years, 24 male) who underwent successful catheter ablation for left posterior fascicular VT and 30 consecutive patients (mean age 57.0±17.8 years, 22 male) who were diagnosed with AFL with RBBB aberrancy where R/S raito in V6 was < 1.0. AFL with RBBB pattern was diagnosed based on the following criteria: 1) AV block during adenosine infusion or treadmill test 2) Induced by electrophysiology study 3) Interrogation of cardiac implantable electronic devices The rS/QRS ratio was defined as the ratio of QRS waveform durations as measured from the QRS onset to nadir of S wave divided by total QRS width in the lead V6.
Results: The Brugada criteria was not applicable because all patients had RS interval <100 msec and r/S ratio <1 in V6. Diagnostic accuracy of previous criteria (Vereckei criteria) was only modest (sensitivity; 56.3%, specificity; 60.0%, PPV; 60.0%, NPV; 56.3%). A significant proportion of AFL was classified as VT, and vice versa. However, the rS/QRS ratio in V6 was significantly lower in AFL than in VT (0.360 ± 0.050 vs 0.466 ± 0.049, P <.001). On receiver operating characteristic curve analysis, rS/QRS ratio cutoff value of <0.41 differentiated the two types of tachycardias with a high diagnostic accuracy (sensitivity; 86.7%, specificity; 93.7%, PPV; 92.9%, NPV; 88.2%).
Conclusions: The ratio of QRS waveforms from the onset of initial R to nadir S/QRS width in V6 <0.41 is a simple and reliable index distinguishing AFL with RBBB pattern from fascicular VT originating from posterior fascicle.
Author Disclosures: M. Kim: None. J. Hwang: None. Y. Hwang: None. J. Lee: None. C. Kwon: None. J. Kim: None. G. Nam: None. K. Choi: None. Y. Kim: None.
- © 2016 by American Heart Association, Inc.