Bedside-focused transthoracic echocardiography in acute atraumatic thoracic aortic syndrome: a systematic review and meta-analysis of diagnostic accuracy

The objective of this review is to assess the diagnostic accuracy of bedside-focused transthoracic echocardiography (TTE) in acute atraumatic thoracic aortic syndrome in adults. We performed a systematic review and meta-analysis of publications that described the use of bedside-focused TTE on adults presenting to the emergency care setting with suspected atraumatic thoracic aortic syndrome. Studies were identified using keyword and Medical Subject Heading searches on databases and grey literature, followed by abstract screening and study selection by two independent reviewers. Sixteen studies over six decades were included in the meta-analysis (n = 4569 patients). The prevalence of Type A thoracic aortic dissection was 11% (range 1.4-45.7%) and Type B dissection was 7% (range 1.8-30.55%). Type A dissection through direct visualisation of an intimal flap on TTE (i.e. direct sign) pooled sensitivity and specificity were 89% [95% confidence interval (CI), 82-94%] and 92% (95% CI, 88-95%) respectively. For Type B dissection, the pooled sensitivity was 65% (95% CI, 45-80%) and specificity was 100% (95% CI, 0.69-100%). TTE indirect signs for dissection showed a pooled sensitivity of 64% (95% CI, 5.2-98.2%) and specificity of 94% (95% CI, 92-96.1%) for aortic valve regurgitation, a pooled sensitivity of 92% (95% CI 54-99.2%) and specificity of 87% (95% CI, 62-97%) for thoracic aortic aneurysm and a pooled sensitivity of 39% (95% CI 33.8-45%) and a specificity of 94% (95% CI, 92-95%) for pericardial effusion. In this systematic review and meta-analysis, bedside-focused TTE has a good specificity for Type A and B dissection, but poor sensitivity for Type B, and unclear for intramural haematoma and penetrating aortic ulcer.