Non-gated high-pitch computed tomography aortic angiography: Myocardial perfusion defects in patients with suspected aortic dissection.

Objectives: To investigate the diagnostic value of first-pass myocardial perfusion defects visualised in non-gated high-pitch computed tomography angiography (CTA) in patients admitted to the emergency department (ED) for suspected aortic dissection.

Methods: We recruited 174 ED patients who underwent high-pitch CTA of the aorta because of suspected aortic dissection. We divided these patients into two groups (diseased and control groups) based on whether their clinical data fulfilled the third universal definition of acute myocardial infarction (AMI), specifically an increase in cardiac troponin (cTn) with at least one of the following: (a) symptoms of ischemia; (b) new ST-segment-T wave (ST-T) changes or new left bundle branch block (LBBB); (c) development of pathological Q wave; (d) new loss of viable myocardium or new regional wall motion abnormality; or (e) identification of an intracoronary thrombus by angiography or autopsy. Twenty-two patients with a clinical diagnosis of AMI were placed in the diseased group. Myocardial perfusion defects were evaluated qualitatively and quantitatively on the late arterial phase obtained 50 s post-threshold.

Results: Of the 22 patients with a final diagnosis of AMI, visually identifiable perfusion defects were observed in 12 patients. The sensitivity, specificity, negative predictive value, and positive predictive value of any perfusion defect for predicting AMI were 54.6%, 94.7%, 93.5%, and 60.0%, respectively. Quantitative analysis indicated that CT attenuation was significantly lower within perfusion defects than within the normal myocardium (67.6 ± 29.5 HU vs. 92.2 ± 19.7 HU; p < 0.001).

Conclusions: In patients with acute chest pain, the presence of myocardial perfusion defect observed on nongated high-pitch CTA of the aorta can be used to identify individuals with AMI with high specificity, but low sensitivity.