Background: The aim of this study was to assess the prognostic value of abnormal coronary computed tomography angiography (CCTA) in patients with normal single-photon emission computed tomography (SPECT) study.
Methods: We retrospectively enrolled patients with normal SPECT scans and abnormal CCTA studies, who were categorized according to CCTA findings into obstructive with ≥50 %, and non-obstructive CAD <50 % coronary artery stenosis. Major adverse cardiac events (MACE) was defined as cardiovascular death and non-fatal myocardial infarction.
Results: Among 1558 eligible patients, there were 1356 (87.1 %) patients with non-obstructive CAD and 202 (12.9 %) patients with obstructive CAD. Over a median follow-up of 10.4 ± 5.1 years, a total of 87 MACEs were reported. Patients with obstructive CAD were older (67.4 ± 8 vs. 60.3 ± 10 years, p < 0.001), more often male (75.0 % vs. 54.6 %, p < 0.001), and had a higher prevalence of diabetes mellitus (26.7 % vs. 17.2 %, p = 0.008) compared with those with non-obstructive disease. Despite normal SPECT findings, patients with obstructive CAD had significantly higher rates of MACE compared with those with non-obstructive CAD [25/202 (12.4 %) vs. 62/1356 (4.8 %), p < 0.001]. Multivariable Cox regression confirmed age (HR 1.21, p = 0.04), diabetes (HR 1.35, p = 0.03), higher coronary calcium score (HR 1.49, p = 0.01), and the presence of obstructive CAD (HR 2.57, p < 0.001) are independent predictors of mortality.
Conclusion: Obstructive CAD on CCTA is associated with significantly higher long-term risk of MACE in comparison to non-obstructive CAD in patients with normal SPECT.