The Relationship Between Spontaneous Echocontrast, Transesophageal Echocardiographic Parameters, and Blood Hemoglobin Levels

Background: Spontaneous echocontrast (SEC) or "smoke" is an intracavitary echocardiographic finding seen in situations of stasis or low blood flow. Increased hematocrit and fibrinogen levels have been associated with SEC in prior studies. Whether low hemoglobin (Hb) levels are an independent predictor of lower prevalence of SEC is a question that remains unanswered. Methods: A total of 266 transesophageal echocardiographic (TEE) studies were reviewed. Hb levels within 1 month from the TEE study were used as the baseline Hb before the study (75% had Hb on the same day of the TEE study). Clinical characteristics and demographics, and all relevant TEE variables including left atrial (LA) size, LA appendage emptying velocity (LAAEV), and presence or absence of SEC, were obtained using electronic patient information system search of TEE reports. Multivariate regression analysis was performed to identify the independent predictors of SEC. Results: Two groups were analyzed SEC (n = 45) or no SEC (n = 221). Only 7 patients had both LA and right atrial SEC. On univariate analysis, male sex, greater age, prior coronary artery bypass grafting, low ejection fraction (<50%), atrial fibrillation, renal failure, aortic atheroma, dilated LA, and decreased LAAEV (<40 cm/s) predicted SEC whereas low Hb levels were significantly associated with a lower prevalence of SEC (P = .01). However, after adjusting for clinical and echocardiographic variables, low Hb levels did not independently predict absence of SEC. Low LAAEV (P < .001), dilated LA (P = .001), and prior statin therapy (P = .001) were the most powerful independent predictors of SEC. Conclusion: A low Hb level is not associated with a lower prevalence of SEC when controlled for clinical and echocardiographic variables. Our study confirms the importance of LAAEV and dilated LA in determining presence of SEC, but also raises interesting questions of the relationship between statins and SEC that warrant further study.