Study of the electrophysiological properties of intravenous bisoprolol in patients with and without coronary artery disease by programmed stimulation.

The objective of this study was to assess the electrophysiological properties of intravenous bisoprolol in patients with and without coronary artery disease (CAD) by programmed stimulation. Sixteen inpatients subjected to an electrophysiological investigation because of dizziness or palpitations were given 10 mg of intravenous bisoprolol after basal measurement and were checked again 15 and 45 min after infusion. Eight patients with CAD (seven males and one female; mean age of 60+/-4 years) and eight patients without CAD (five males and three females; mean age of 59+/-4 years) were investigated after washout of prior antiarrhythmic drugs. For coronary patients, the CAD was documented by a history of myocardial infarction or by a confirmatory coronary arteriography. Main outcome measures were parameters of invasive electrophysiological exploration, with measurement of conduction intervals at rest and during pacing and of refractory periods by means of extrastimulus technique. No significant difference was noted at baseline between the two groups except for CSNRT. After infusion of 10 mg of bisoprolol, with the exception of CSNRT (increased in the group without CAD), no significant differences were noted on comparison between coronary and noncoronary patients. Bisoprolol significantly increased the sinus cycle length, SACT, and FRP of the atria. Regarding atrioventricular nodal conduction, bisoprolol significantly increased the AH 100, ERP, and FRP and significantly decreased the Wenckebach point. In the right ventricle, bisoprolol moderately, but significantly, decreased the corrected QT and induced a small, temporary, significant increase in ERP. Bisoprolol appears to be a very potent beta-blocker that is well tolerated at an intravenous dose of 10 mg. Its depressant effects concern mainly the atrial function and the nodal conduction, without significant differences between the two groups of patients. The decrease in QTc may be a favorable aspect regarding its electrophysiologic tolerance especially in the acute phase of myocardial infarction.