Efficacy of myocardial contrast echocardiography in the diagnosis and risk stratification of acute coronary syndrome.

We examined the hypothesis that myocardial contrast echocardiography (MCE) is superior to conventional electrocardiographic, echocardiographic, and troponin I criteria for the diagnosis of acute coronary syndrome. We prospectively enrolled 114 consecutive patients (60+/-10 years of age, 73 men) who presented to the emergency room with chest pain on exertion and at rest. Exclusion criteria included an age<40 years, presence of Q wave or ST-segment elevation, and a poor echocardiographic window. Echocardiography and MCE were performed to assess regional wall motion abnormalities (RWMAs) and myocardial perfusion defects by using continuous infusion of perfluorocarbon-exposed sonicated dextrose albumin. Acute coronary syndrome was confirmed in 87 patients. There were no deaths; 46 patients had acute myocardial infarction, and 41 patients required urgent revascularization. On multiple logistic regression analysis, myocardial perfusion defect (odd ratio 87, p<0.001) was the only independent variable for diagnosing acute coronary syndrome. Myocardial perfusion defect (odd ratio 21, p=0.001) and troponin I levels (odd ratio 3, p=0.009) were independent predictors for acute myocardial infarction. The sensitivity of myocardial perfusion defect for diagnosing acute coronary syndrome was 77%, which is significantly higher than the sensitivities of ST change, troponin I increase, and RWMA (28%, 34%, and 49%, respectively), with similar specificities of 85% to 96%. In conclusion, MCE is more sensitive than the currently used electrocardiographic and troponin I criteria, and evaluation of myocardial perfusion defect by MCE complements RWMA analysis by conventional echocardiography for accurate diagnosis of acute coronary syndrome.