Effects of nitroglycerin on the diagnostic accuracy of electrocardiogram-gated coronary computed tomography angiography

Objectives: To evaluate the effect of nitroglycerin on the diagnostic accuracy of electrocardiogram-gated coronary computed tomography (CT) angiography in patients with suspected coronary artery disease. Methods: Computed tomography angiography was performed on 76 patients using a 16-slice CT scanner. Forty-six patients received a sublingual nitroglycerin I minute before CT scanning (the NTG group), but the other 30 did not (the non-NTG group). No statistically significant differences were evident between these 2 groups in terms of clinical and demographic characteristics. Significant stenosis (>= 50% diameter reduction) as determined by CT was evaluated according to patient-based and segment-based analyses, and results were compared with conventional coronary angiographic findings. In addition, segments of the coronary artery were reclassified by segment luminal size into proximal, mid, and distal segments, and the diagnostic accuracies of the NTG and non-NTG approaches were evaluated in these segments. Results: Differences in heart rate, and systolic and diastolic blood pressures before and after using nitroglycerin were 1.0 +/- 2.4 beats per minute, -8.3 +/- 14.4 mm Hg, and -4.6 +/- 10.6 mm Hg, respectively. Sensitivity, specificity, and positive and negative predictive values in the NTG group were higher than in the non-NTG group by patient-based analysis (P = 0.25) and by segment-based analysis (P < 0.05). In addition, based on the luminal size of each segment, diagnostic accuracy in the NTG group was significantly higher for proximal segments than in the non-NTG group (96.7% vs 89.7%; P < 0.05). Conclusions: The use of nitroglycerin was found to be safe and to improve the diagnostic accuracy of coronary CT angiography for the evaluation of coronary artery disease.