Is nitroglycerin still necessary for coronary CT angiography in the era of photon-counting CT?

Sublingual nitroglycerin is routinely administered before coronary computed tomography angiography (CCTA) to improve coronary artery visualization. However, most supporting evidence originates from older-generation CT systems and focuses on image quality rather than diagnostic accuracy. The impact of nitroglycerin on the diagnostic performance of photon-counting detector CT (PCD-CT) CCTA remains unknown.

In this retrospective single-center study, consecutive patients who underwent photon-counting CCTA between January 2023 and November 2025 and invasive coronary angiography (ICA) within 30 days were identified. The final cohort consisted of 124 patients, including 61 who received sublingual nitroglycerin and 63 who did not. Diagnostic performance for detecting obstructive coronary artery disease was assessed on both a per-patient and per-vessel basis using ICA as the reference standard. Objective image quality was evaluated using coronary attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR).

On per-patient analysis, sensitivity was similar between the nitroglycerin and non-nitroglycerin cohorts (90.3% vs. 90.9%, p = 0.940), as was NPV (86.4% vs. 88.9%, p = 0.780). Non-nitroglycerin cohort demonstrated numerically higher specificity (80.0% vs. 63.3%, p = 0.160), PPV (83.3% vs. 71.8%, p = 0.250), and overall accuracy (85.7% vs. 77.0%, p = 0.220), although these differences were not statistically significant. No significant differences were observed on per-vessel analysis. Nitroglycerin increased coronary attenuation but did not improve SNR or CNR.

In patients undergoing photon-counting CCTA, sublingual nitroglycerin administration was not associated with a statistically significant improvement in per-patient or per-vessel diagnostic performance. These findings should be considered hypothesis-generating and require confirmation in larger prospective studies before any conclusions can be drawn regarding the incremental value of routine nitroglycerin administration in photon-counting CCTA.