Differing susceptibility of echocardiographic contrast agents to adverse effects of biologic factors: Multicenter, videodensitometric comparison of octafluoropropane-filled microspheres with air-filled microspheres for left ventricular opacification

Background: Echocardiographic contrast enhancement of the left ventricle ha s diagnostic value in the assessment of regional and global left ventricula r (LV) function. The efficacy of both octafluoro-propane-filled human album in microbubbles (OCTA) and of air-filled human albumin microbubbles (AIR) f or LV endocardial delineation and qualitative LV opacification has previous ly been reported. However, pulmonary disease, obesity, impaired LV function , and decreased echogenicity may diminish the efficacy of contrast agents f or LV opacification. The purpose of this study was to compare the susceptib ility of 2 contrast agents currently approved by the Food and Drug Administ ration to these biologic factors. Methods: To compare quantitative LV opacification with OCTA (0.2, 0.5, 3.0, 5.0 mt) versus AIR (0.08 mL/kg, 0.22 mL/kg), we performed videodensitometr y in 199 patients (average age 59.2 +/- 13.3 years, 79% men) studied in 2 I dentical, prospective, multicenter, blinded trials, of whom 74 had impaired LV function, pulmonary disease, or both, 70 were obese (body mass index >3 0 kg/m(2)), and 45 were nonechogenic (greater than or equal to 4 of 6 endoc ardial segments were not seen in the apical 4-chamber view). Changes in vid eodensity from noncontrast to contrast agent with the same gain settings we re determined at end diastole and end systole (gray scale 0 to 255 U) for 2 regions of interest: left ventricle apex-to-mid-cavity and mid-cavity-to-b ase. The relative influence of clinically evident pulmonary disease, impair ed LV function on echocardiography, and echogenicity on LV opacification pr oduced by both contrast agents was determined by multivariate analysis. Results: Significant videodensity increases ranging from 67% to 143% were o bserved with both agents. At the recommended initial doses (0.5 mt for OCTA , 0.22 mL/kg for AIR), OCTA produced greater opacification than AIR in both regions of interest and at both phases of the cardiac cycle. Poor LV funct ion was associated with decreased LV opacification for AIR but not for OCTA . Diminished echogenicity was more strongly associated with impaired opacif ication for AIR than for OCTA. Obesity and clinically evident pulmonary dis ease were associated with diminished chamber opacification with both OCTA a nd AIR. Conclusions: In addition to the superiority of octa-fluoropropane-filled mi crospheres to air-filled microspheres for LV opacification, the efficacy of OCTA is relatively unaffected by impaired LV function and is less suscepti ble to the effects of poor echogenicity than AIR.