Volume 17, Issue 2, March 2016.
Margarita E. Pena, MD, et al.

Introduction: Clinicians are urged to decrease radiation exposure from unnecessary medical
procedures. Many emergency department (ED) patients placed in an observation unit (EDOU) do not
require chest pain evaluation with a nuclear stress test (NucST). We sought to implement a simple
ST algorithm that favors non-nuclear stress test (Non-NucST) options to evaluate the effect of the
algorithm on the proportion of patients exposed to radiation by comparing use of NucST versus NonNucST
pre- and post-algorithm.
Methods: An ST algorithm was introduced favoring Non-NucST and limiting NucST to a subset of
EDOU patients in October 2008. We analyzed aggregate data before (Jan-Sept 2008, period 1) and
after (Jan-Sept 2009 and Jan-Sept 2010, periods 2 and 3 respectively) algorithm introduction. A
random sample of 240 EDOU patients from each period was used to compare 30-day major adverse
cardiac events (MACE). We calculated confidence intervals for proportions or the difference between
two proportions.
Results: A total of 5,047 STs were performed from Jan-Sept 2008-2010. NucST in the EDOU
decreased after algorithm introduction from period 1 to 2 (40.7%, 95% CI [38.3-43.1] vs. 22.1%, 95%
CI [20.1-24.1]), and remained at 22.1%, 95% CI [20.3-24.0] in period 3. There was no difference in
30-day MACE rates before and after algorithm use (0.1% for period 1 and 3, 0% for period 2).
Conclusion: Use of a simple ST algorithm that favors non-NucST options decreases the proportion
of EDOU chest pain patients exposed to radiation exposure from ST almost 50% by limiting NucST
to a subset of patients, without a change in 30-day MACE.