Variable response to atrial pacing after intravenous propranolol in patients with stable exertional angina

Abstract

The effect of propranolol administration on regional coronary haemodynamics were investigated in 14 patients with stable exertional angina and isolated left anterior descending artery disease. Thermodilution was used to measure great cardiac vein flow (GCVF) and anterior regional coronary resistance (ARCR) under control conditions, at peak atrial pacing, after i.v. propranolol administration (0.1 mg kg-1) and at the peak of repeated atrial pacing. Propranolol did not change peak pacing heart rate, systolic blood pressure or double product. Peak pacing GCVF decreased slightly but non-significantly after drug administration from 84 +/- 20 to 79 +/- 24 ml min-1, while ARCR increased, but again non-significantly, from 1.36 +/- 0.44 to 1.45 +/- 0.45. Analysis of individual patient responses revealed that propranolol prolonged peak pacing time and hence peak pacing heart rate (from 126 +/- 24 to 140 +/- 23 beats min-1, P less than 0.05) in five patients. In such patients, peak pacing systolic blood pressure was lower than the pre-propranolol atrial pacing (145 +/- 35 vs 165 +/- 33, P less than 0.001) so that double product remained unchanged. Moreover, peak pacing ARCR did not change after propranolol (pre-propranolol 1.47 +/- 0.46, after propranolol 1.40 +/- 0.56 mmHg.ml-1.min, P = ns) while it increased significantly in the nine patients who did not improve after the drug (before propranolol 1.30 +/- 0.44, after propranolol 1.48 +/- 0.41 mmHg.ml-1.min, P less than 0.02). These data suggest that the response to atrial pacing after i.v. propranolol administration is variable as some patients tolerate higher heart rates while others do not.(ABSTRACT TRUNCATED AT 250 WORDS)

Gly389Arg polymorphism of β1-adrenergic receptor is associated with the cardiovascular response to metoprolol

“…It has long been known by cardiologists who have used β‐blockers in patients with heart failure or hypertension that there are responders and nonresponders to this therapy 31 , 32 . Many attempts have been made to identify responders, but the association with different markers is only slight.…”

“…17,29,30 It has long been known by cardiologists who have used ␤-blockers in patients with heart failure or hypertension that there are responders and nonresponders to this therapy. 31,32 Many attempts have been made to identify responders, but the association with different markers is only slight. Our data showed that the subjects with the Arg389 genotype had an exaggerated response of the heart rate and systolic blood pressure to metoprolol.…”