Implications of 25% to 50% coronary stenosis with cardiac computed tomographic angiography in ED patients.

OBJECTIVE: The aim of this study was to determine if patients presenting with symptoms of acute coronary syndrome and found to have 25% to 50% diameter reduction with coronary computed tomographic angiography (CCTA) are likely to benefit from further diagnostic testing.
METHODS: A registry study of 213 subjects (median age, 51 years; 53% women) with symptoms concerning for possible acute coronary syndrome with low-risk features found to have 25% to 50% maximal diameter stenosis on CCTA was performed at 2 academic medical centers. The analysis was approved by an institutional review board and was conducted with waiver of consent. The potential contribution of additional testing was determined by measuring the major adverse cardiac events (MACEs) from presentation through 30 days. The MACEs included myocardial infarction, coronary revascularization, unstable angina, and cardiovascular death. Sample size calculations were predicated on a 0% MACE rate leading to upper bounds of a 2-sided exact 95% confidence interval less than 2%.
RESULTS: Thrombolysis in myocardial infarction risk score of less than 2 was present in 92% subjects, 70% (150 of 213) had 2 or more serial cardiac markers performed, and 40% (87 of 213) had stress testing or cardiac catheterization. The MACEs occurred in 1 (0.5%) of 213 subjects (95% confidence interval, 0%-2.6%) and was identified by an elevation of serial cardiac markers during the index hospitalization. No patients experienced cardiovascular death or required revascularization.
CONCLUSIONS: In patients with emergent low-risk chest pain and 25% to 50% diameter coronary stenosis by CCTA, the rate of near-term MACE is very low. Serial cardiac markers may be beneficial in this subgroup. Routine provocative testing is unlikely to be beneficial during the index visit.