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Aims To compare the cost-effectiveness of coronary computed tomography angiography (CCTA) vs. myocardial single photon emission computed tomography (SPECT) in patients with stable intermediate risk chest pain. Methods and results Non-acute patients with 10–90% pre-test probability of coronary artery disease from three high-volume centres in Korea (n  = 965) were randomized 1:1 to CCTA or myocardial SPECT as the initial non-invasive imaging test. Medical costs after randomization, the downstream outcome, including all-cause death, acute coronary syndrome, cerebrovascular accident, repeat revascularization, stent thrombosis, and significant bleeding following the initial test and the quality-adjusted life-years (QALYs) gained by the EuroQoL-5D questionnaire was compared between the two groups. In all, 903 patients underwent the initially randomized study (n  = 460 for CCTA, 443 for SPECT). In all, 65 patients underwent invasive coronary angiography (ICA) in the CCTA and 85 in the SPECT group, of which 4 in the CCTA and 30 in the SPECT group demonstrated no stenosis on ICA [6.2% (4/65) vs. 35.3% (30/85), P -value < 0.001]. There was no difference in the downstream clinical events. QALYs gained was higher in the SPECT group (0.938 vs. 0.955, P -value = 0.039) but below the threshold of minimal clinically important difference of 0.08. Overall cost per patient was lower in the CCTA group (USD 4514 vs. 5208, P -value = 0.043), the tendency of which was non-significantly opposite in patients with 60–90% pre-test probability (USD 5807 vs. 5659, P -value = 0.845). Conclusion CCTA is associated with fewer subsequent ICA with no difference in downstream outcome. CCTA may be more cost-effective than SPECT in Korean patients with stable, intermediate risk chest pain. [ABSTRACT FROM AUTHOR]

Background: Although invasive physiological assessment for coronary stenosis has become a standard practice to guide treatment strategy, coronary circulatory response and changes in invasive physiological indexes, according to different anatomic and hemodynamic lesion severity, have not been fully demonstrated in patients with coronary artery disease.Methods: One hundred fifteen patients with left anterior descending artery stenosis who underwent both 13N-ammonia positron emission tomography and invasive physiological measurement were analyzed. Myocardial blood flow (MBF) measured with positron emission tomography and invasively measured coronary pressures were used to calculate microvascular resistance and stenosis resistance.Results: With progressive worsening of angiographic stenosis severity, both resting and hyperemic transstenotic pressure gradient and stenosis resistance increased (P<0.001 for all) and hyperemic MBF (P<0.001) and resting microvascular resistance (P=0.012) decreased. Resting MBF (P=0.383) and hyperemic microvascular resistance (P=0.431) were not changed and maintained stable. Both fractional flow reserve and instantaneous wave-free ratio decreased as angiographic stenosis severity, stenosis resistance, and transstenotic pressure gradient increased and hyperemic MBF decreased (all P<0.001). When the presence of myocardial ischemia was defined by both low hyperemic MBF and low coronary flow reserve, the diagnostic accuracy of fractional flow reserve and instantaneous wave-free ratio did not differ, regardless of cutoff values of hyperemic MBF and coronary flow reserve.Conclusions: This study demonstrated how the coronary circulation changes in response to increasing coronary stenosis severity using 13N-ammonium positron emission tomography-derived MBF and invasively measured pressure data. Currently used resting and hyperemic pressure-derived invasive physiological indexes have similar patterns of relationships to the different anatomic and hemodynamic lesion severities.Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01366404. [ABSTRACT FROM AUTHOR]