PURPOSE: The purpose of our study was to compare coronary luminal diameters in patients undergoing coronary computed tomography angiography (CCTA) performed with different sublingual nitroglycerin (NTG) spray regimens. MATERIALS AND METHODS: We retrospectively reviewed CCTA studies performed in two historical groups (Group 1, single dose nitroglycerin 2 min prior to CCTA, and Group 2, single dose 10 min prior), and a current protocol group (Group 3, single dose at 2 and 10 min prior). Thirty patients were evaluated per group. Two blinded readers measured coronary luminal diameters with comparison of diameter measurements. A third blinded reader assessed image quality of coronary artery segments. RESULTS: Significant group-level differences in median luminal diameters were identified. Higher median diameters (95% CI) across all segments of 0.40 mm (0.20, 0.60) for Group 2 versus 1 and 0.50 mm (0.30, 0.70) for Group 3 versus 1 were recorded (both P < 0.001). No significant differences in median luminal diameters were found between Groups 2 and 3. No significant differences in image quality were found among the groups apart from higher image quality for the distal LAD for both Groups 2 and 3 compared to Group 1. CONCLUSION: Sublingual nitroglycerin spray administered as a single dose at 10 minute dilates coronary arteries more than when only administered at 2 min prior to CCTA. Combined two doses at 10 and 2 min prior to CCTA do not yield further dilatation of coronary arteries.
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