Association of Early Noninvasive Cardiac Stress Testing with Acute Myocardial Infarction and Mortality.

STUDY OBJECTIVE:The evaluation for suspected acute coronary syndrome is a common and high-risk presentation in emergency departments (EDs). After exclusion of acute myocardial infarction (MI), patients often undergo early (within 72 hours) noninvasive cardiac testing. We evaluated the association between early noninvasive testing and death/acute MI in ED patients suspected of acute coronary syndrome. METHODS:We used a retrospective cohort study design within the adult ED patient population (from October 2015 to December 2020) in whom MI was ruled out, belonging to a large integrated health care delivery system. Using data on history (H), electrocardiogram (E), age (A), risk factors (R), and troponin (T), we computed the HEART risk score. We stratified the cohort into low (score 0 to 3), intermediate (score 4 to 6), and high (score ≥7) risk and followed them up to 1-year after ED discharge. The association between noninvasive testing within 3 days of the ED visit and composite risk of death/acute MI within 1-year of discharge was evaluated by propensity score analysis. RESULTS:The cohort included 174,917 patients (61% low risk [age 53; women 58%; noninvasive testing 5%], 36% intermediate risk [age 71; women 52%; noninvasive testing 18%], and 3% high risk [age 74, women 45%; noninvasive testing 23%]). The risk reduction in death/acute MI associated with early noninvasive testing was -1.54% (-1.95% to -1.12%) number needed to treat (NNT)=65; -4.93% (-5.66% to -4.20%) NNT=20, and -8.98% (95% confidence interval -11.32% to -6.64%) NNT=11; and, in the low, intermediate, and high-risk respectively. CONCLUSION:Early noninvasive testing was associated with reduced risk of 1-year death or acute MI across all risk groups.