Clinical and anatomical characteristics of subtle-discrete dissection of the ascending aorta.

Subtle or discrete (class 3 in the classification of the European Society of Cardiology) dissection is the most neglected variant of aortic dissection. This study was conducted to define the clinical manifestations, diagnostic findings, and outcomes of subtle or discrete dissection involving the ascending aorta. The clinical and surgical records, preoperative studies, and outcomes of 109 consecutive patients with ascending aortic dissection observed from 1995 to 2005 were reviewed. Eight patients (7.3%) had discrete dissection. Five patients presented with acute anterior chest pain, 2 with abdominal pain, and 4 with syncope. The mean diameter of the ascending aorta was 44 +/- 8.8 mm. The intimal tears were located in all patients on the posterior aspect of the ascending aorta 1 to 40 mm above the left coronary ostium; its length varied from 2.8 to 12.3 mm. Preoperative aortography, magnetic resonance imaging, and computed tomography could not identify the discrete intimal tears. Transesophageal echocardiography provided unique diagnostic information on (1) subtle intimal discontinuity, (2) circumscribed intramural hematoma, and (3) discrete pericardial fluid around the dissected aorta. Six patients underwent emergency surgery on the basis of echocardiographic findings, and they were all alive at follow-up. Compared with patients with classic aortic dissection, those with discrete dissection had lower operative mortality (0% vs 26%, p = 0.11), shorter hospital stay (7.2 +/- 2.8 vs 21 +/- 19 days, p = 0.01), and less frequent need for blood transfusions (0% vs 39%, p = 0.02). In conclusion, elevated clinical suspicion and detailed transesophageal echocardiographic examination are important for the early identification of discrete aortic dissection, leading to prompt surgery, shorter hospital stays, and better outcomes.