Beta-Adrenergic Influences on T Wave Alternans During Pacing in Patients With and Without Ventricular Tachyarrhythmia

Presentation Time: Monday, 10:00 a.m. - 11:00 a.m.

Norihiro Komiya, Shinji Seto, Kojiro Nakao, Kiyotaka Matsuo, Hisashi Doi, Motonobu Hayano, Katsusuke Yano, The Third Department of Internal Medicine,Nagasaki University School of Medicine, Nagasaki, Japan.

Presentation Number: 1093-107

Poster Board Number: 107

Keyword: Autonomic nervous system, Ventricular arrhythmia, Beta-adrenergic receptor blockers, Beta-adrenergic receptor agonists

Backgrounds: T wave alternans (TWA) is a measure of ventricular vulnerability. Relation of TWA to adrenergic activity is not assessed clinically. This study was to evaluate (1) whether adrenergic influence on TWA is observed clinically, and if so, (2) whether responses of TWA to changes in adrenergic activity are relevant to patients (pts) with ventricular tachyarrhythmia (VT).
Methods: 35 pts (28 M, 7 F; 58+/-14 years) consisted of 24 with supraventricular arrhythmia and 11 with VT are included. The magnitude of TWA in lead Vector Magnitude (eMV) was measured during atrial pacing of 90 and 110 ppm. Adrenergic influence on TWA was examined comparing eMV of on baseline and after 2 mg/kg of propranolol (PRO) infusion. In 12 pts (5 with VT, 7 without VT), eMV was also measured during 0.01 microgram/kg/min of isoproterrenol (ISP) infusion.
Results: The eMV in whole 35 pts decreased from 1.42+/-1.14 to 0.61+/-0.87 (p<0.05) by PRO at 110 ppm, and ISP increased to 3.64+/-3.25 . Effect of PRO and ISP on eMV in pts with and without VT were summarized in Table. On baseline, eMV was larger in VT pts (p<0.05). However, after PRO, a greater diminution of eMV was observed in VT pts (p<0.05). Contrarily, ISP caused a lesser increase of eMV in VT pts.
Conclusion: TWA was regulated, at least partly, by beta-adrenergic activity. Characteristics in VT pts were larger diminution of TWA after beta-blockade and smaller increase during beta-stimulation; suggesting an augmentation of intrinsic beta-adrenergic activity in VT pts.

Effect of PRO and ISP on eMV in pts with and without VT. * P < 0.05 versus baseline

 

VT
90 ppm

Non VT
90ppm

VT
110ppm

Non VT
110ppm

baseline

1.32+/-0.47

0.29+/-0.29

2.45+/-0.97

1.16+/-0.94

PRO

0.47+/-0.33*

0.28+/-0.48

0.89+/-0.40*

0.45+/-0.65*

ISP

1.58+/-1.73

1.67+/-1.84

3.06+/-2.01

3.88+/-3.82