Impact of a decision rule on duration of continuous cardiac monitoring of patients with suspected acute coronary syndrome in an emergency department

BACKGROUND/AIMS: To determine the effect of introducing a decision rule on the duration of continuous cardiac monitoring (CCM) for patients with suspected acute coronary syndrome in an adult emergency department (ED). METHODS: This was a retrospective observational study of 220 patients with suspected acute coronary syndrome made up of two consecutive cohorts collected before and after introduction in July 2010 of a decision rule that made use of a new high-sensitivity troponin T assay. The primary outcome was median CCM duration in the ED (CCMED). Secondary outcomes were median duration of CCM in the first 24 h, rate of adverse events, proportion of patients after the intervention who had the rule adhered to, and estimated median CCMED had the decision rule been adhered to by all patients. RESULTS: The decision rule was adhered to in 59.3% (95% confidence interval 49.8-68.1) of patients post-intervention. There was no statistically or clinically significant difference in median CCMED before (240 min, interquartile range 156-313) and after (230 min interquartile range 145-353) introduction of the decision rule (P = 0.74) nor in CCM in the first 24 h (908 min vs 929 min). Seven (3.2%, 95% confidence interval 1.4-6.6) adverse events occurred overall. All three patients with adverse events after the intervention were monitored in ED according to the decision rule. CONCLUSION: Introduction of this decision rule did not decrease the median CCMED. All adverse events after the intervention occurred in appropriately monitored patients, including patients with initially negative high-sensitivity troponin T, suggesting that the decision rule would not compromise patient safety.