To the Editor:
In “Perioperative β-blockade: Atenolol Is Associated with Reduced Mortality When Compared to Metoprolol,” Wallace et al. make a strong case for preferring atenolol for perioperative ß-blockade.1As the authors note, their results are consistent with our prior meta-regression of randomized controlled trials2and the large observational analysis by Redelmeier.3
In the absence of renal insufficiency that alter the kinetics of atenolol, atenolol has favorable pharmacokinetic characteristics compared with metoprolol. However, if we are to use atenolol, we must know its optimal dosing interval. Originally, all ß-blockers were recommended for once-daily dosing4; however, since the early 1990s, the variable duration of ß-blockers has been recognized.5Some studies have found that atenolol does not provide 24 h of ß-blockade.6,7As Wallace et al. note, Freestone found that atenolol has more predictable ß-blockade at 24 h than does metoprolol.8However, Freestone's group also reported that atenolol's reduction of the pulse during exercise was less at 24 h than at 3 [1/2] h after dosing.9The INVEST study dosed atenolol twice a day if more than 50 mg per day was needed.10
Dr. Wallace coauthored the Multicenter Study of Perioperative Ischemia trial, which is the largest placebo-controlled trial of atenolol for perioperative ß-blockade.11A strength of the Multicenter Study of Perioperative Ischemia trial is continuous Holter monitoring. The Multicenter Study of Perioperative Ischemia trial dosed atenolol once per day and reported trends, although insignificant, toward increased perioperative mortality and stroke among patients treated with atenolol.11
Since we share Dr. Wallace's interest in atenolol, we hope he would be willing to resurrect the trial data and publish an analysis of it for diurnal variation in morbidity and electrocardiographic events in order to further evaluate the optimal dosage interval for atenolol.
*Kansas University School of Medicine-Wichita, Wichita, Kansas. email@example.com