Prognostic significance of spontaneous echo contrast in the thoracic aorta: relation with accelerated clinical progression of coronary artery disease.

Objectives: The purposes of this study were to identify the incidence of aortic smoke in an unselected cohort of patients and to determine the utility of this measurement as a clinical marker for future coronary events and long-term cardiac prognosis.

Background: Although spontaneous echo contrast detected within the cardiac chambers has been associated with an increased risk of thromboembolism, less is known about "smoke" within the thoracic aorta and its relation to progression of coronary artery disease.

Methods: We prospectively assessed 118 unselected, consecutive male patients (mean age 67 years, range 29 to 86) who underwent transesophageal echocardiography (TEE). The presence of aortic smoke was identified by swirling echodense shadows distinct from high gain artifact. A positive result required confirmation by two of three independent observers.

Results: Aortic smoke without dissection was found in 25 of the patients (21%). Indications for TEE, coronary risk factors, the incidence of reduced left ventricular ejection fraction and mitral insufficiency and known coronary artery disease severity collectively did not differ significantly at baseline between the groups with and without smoke. Follow-up averaged 20.4 months (range 18 to 24) and was 100% complete for mortality and 98% complete for morbidity. The presence of aortic smoke was an independent predictor of myocardial infarction (16.0% vs. 2.2%, p < 0.005) and cardiac death (20.0% vs. 1.1%, p < 0.0001). These statistics remained significant after covarying for age, ejection fraction < 50%, hypertension, diabetes, aortic dimension, the presence of an atheromatous plaque and smoke in the left atrium.

Conclusions: Spontaneous echo contrast detected within the thoracic aorta by transesophageal echocardiography is a common and important clinical marker that is strongly associated with an increased risk for future myocardial infarction and cardiac mortality. Future studies will attempt to define the pathophysiology of this relation and assess whether aggressive revascularization strategies and antithrombotic therapy may aid in the reduction of this risk.