Rate Control With Beta-blockers Versus Calcium Channel Blockers in the Emergency Setting: Predictors of Medication Class Choice and Associated Hospitalization.

OBJECTIVES

Rate control is an important component of the management of patients with atrial fibrillation (AF). Previous studies of emergency department (ED) rate control have been limited by relatively small sample sizes. We examined the use of beta-blockers (BBs) versus nondihydropyridine calcium channel blockers (CCBs) in ED patients from 24 sites and the associated hospital admission rates.

METHODS

In this preplanned substudy, we examined chart data on AF patients who visited one of 24 hospital EDs in Ontario, Canada, between April 2008 and March 2009. We describe the proportion of patients who received either a BB or a CCB, had a heart rate < 110 beats/min 2 hours later, and had any complications. We used hierarchical logistic regression modeling to determine the predictors of BB versus CCB use and to assess the between-hospital variation in use of BBs versus CCBs. Solely in patients who had no rhythm control attempts, we examined the difference in the probability of hospital admission after propensity score matching patients by medication class.

RESULTS

Of the 1,639 patients who received either a BB (n = 429) or a CCB (n = 1,210), 70.9% of the patients who received a BB had successful rate control versus 66.1% for a CCB. Complications were rare (2.4%), and the large majority were hypotension (2.0%). In adjusted analyses, predictors of receiving a BB (compared to a CCB) included already being on a BB, being sent in from a doctor's office, or being seen at a teaching hospital. In contrast, patients with evidence of heart failure, prior use of a CCB, a higher presenting heart rate, or a successful pharmacologic cardioversion (vs. no attempt) or who were seen at the highest AF volume EDs were significantly less likely to receive a BB, compared to a CCB. Systematic between-hospital differences accounted for 8% of the variation in BB versus CCB use. Hospital characteristics accounted for the large majority of that variation: after accounting for patient characteristics the between-hospital variation decreased by a relative 2.8%. By further adjusting for hospital characteristics, it decreased by a relative 74.7%. Among propensity score-matched patients with no rhythm control attempts, more CCB patients were admitted (51.6%) compared to BB patients (40.0%; difference of 11.6%; 95% confidence interval = 7.9%-16.2%).

CONCLUSIONS

In this study of 24 EDs, CCBs were used more frequently for rate control than BBs, and complications were rare and easily managed using both agents. Variation between hospitals in BB versus CCB use was predominantly due to hospital characteristics such as teaching status and AF volumes, rather than different case mix. Among patients who did not receive attempts at rhythm control, use of a BB for rate control was associated with a lower rate of hospitalization.