Abstract Title:

Does Biventricular Pacing Decrease the Incidence of Microvolt T-Wave Alternans?

Presentation Start:

Sunday, Mar 30, 2003, 10:00 AM -11:00 AM

Topic:

Clinical Electrophysiology--Ventricular Arrhythmias

Author Block:

Raymond C. Leung, Sajad Gulamhusein, Alberta Van Schaik, Katherine Kavanagh, University of Alberta, Edmonton, AB, Canada

Background: Biventricular pacing (BiVP) improves symptoms and hemodynamics in heart failure patients with ventricular conduction delay. Controversy exists as to why a significant reduction of ventricular arrhythmia was observed in patients with BiVP. Presence of microvolt T-wave alternans (TWA) during rapid atrial pacing is independently predictive of ventricular arrhythmic events. We hypothesize that BiVP reduces ventricular arrhythmias by repolarization resynchronization as measured by a reduction of TWA. Methods: Patients (n=13) with permanent BiVP were studied. TWA were measured by spectral method using Heartwave system (Cambridge Heart) at rapid atrial (AAI) and various ventricular (DDD) pacing modes. TWA were interpreted by standard protocol. Results: Four patients were excluded due to AV block at <105 bpm. The results of the remaining 9 patients are shown below. In AAI pacing, 8 of the 9 patients (89%) have positive TWA. Comparatively, frequency of positive TWA was reduced to 67% (6/9; RRR=25%; p=0.57) in DDD-RV, 44% (4/9; RRR=50%; p=0.13) in DDD-LV and 22% (2/9; RRR=75%; p=0.018) in DDD-BiV. Conclusion: BiVP improves repolarization properties as measured by a reduction of TWA, thus contributing to the reduction of ventricular arrhythmias through this novel mechanism.

T Wave Alternans @ 105 bpm

AAI

RV

LV

BiV

-

-

-

-

+

-

-

-

+

+

-

-

+

+

-

-

+

+

-

-

+

-

+

-

+

+

+

-

+

+

+

+

+

+

+

+