To examine the value of antimyosin-indium 111 imaging in relation to endomyocardial biopsy in patients with suspected myocarditis.

To examine the value of antimyosin-indium 111 imaging in relation to endomyocardial biopsy in patients with suspected myocarditis, as well as the natural evolution of abnormal findings forward the antimyosin scan, 12 patients with suspected myocarditis underwent endomyocardial biopsy and antimyosin scan. The heart-to-lung ratio (H/L) was used to quantify the antimyosin scan. All 12 patients had abdormal consequence s on the scan (H/L, 17 to 29; mean, 21 [+ or -] 03); 8 of the 12 patients also had a diagdostic endomyocardial biopsy. In four patients with abnormal findings upon antimyosin scan and normal findings onward biopsy, the H/L ratio did not differ from eight patients with abnormal findings onward antimyosin scan and a diagnostic biopsy; also, the ejection fraction did not differ between the sum of two units groups. One patient died, and 8 patients had a repeat antimyosin scan within 2 month after the initial consideration The H/L ratio returned to normal in couple out of three patients with normal rises on biopsy and in three not at home of five patients with a diagnostic biopsy; the ejection fraction improved according to 8 percent or more in individual out of three patients with a nondiagnostic biopsy ad in brace out of five patients with a biopsy diagnostic for myocarditis. We decide that the antimyosin scan is more many times diagnostic than biopsy in suspected myocarditis. Patients with abnormal eventuates on antimyosin scan and a nondiagnostic biopsy, as well as those with abnormal outcomes on antimyosin scan and a diagnostic biopsy, attend to to return to normal proceeds on scan within 2 month and improve their ejection fraction.

H/L ratio = heart-to-lung ratio

Monoclonal antimyosin antibodies labeled with indium 111 (111 In) have been useful for detecting active myocyte damage; these antibodies have been shown to bind specifically to cardiac myocytes that have forfeited membrane integrity and exposed myosin to the extracellular space.[1] Because myocardial necrosis is an obligatory element of myocarditis,[2] 111 In monoclonal antimyosin antibody imaging has been used to diagnose myocarditis;[3-5] although the sensitivity of the system appears to be high, specificity is sole moderate compared to endomyocardial biopsy. The cause of abnormal flows on antimyosin imaging associated with a nondiagnostic endomyocardial biopsy is unresolv and may give an account of either a false-positive scan or a false-negative biopsy. It has been reported that the sensitivity of biopsy is limited; Chow et al[6] showed that despite 172 biopsies by means of patient, only 79 percent of the cases could be diagnosed; also Hauck et al[7] reported that the commonness of false-negative results of biopsy was 37 percent level when 10 biopsies per case were obtained.

The evolution of the antimyosin scan in cases of suspected myocarditis, in relation to left ventricular function, could be helpful in clarifying the issue of a false-positive antimyosin scan or a false-negative biopsy. The natural evolution of the antimyosin scan has been studied no other than in a murine myocarditis model[8] The at hand study examined the value of 111 In antimyosin antibody cardiac imaging in a dispose of patients strongly suspected of having myocarditis, as well as the natural evolution of the ejection fraction and the antimyosin scan.

Material and Methods

Twelve patients suspected of having acute myocarditis were studied; 2 were women and 10 were men with a mean age of 36 [+ or -] 13 years (range, 18 to 58 years). Eleven patients had experienced the newly come onset of congestive heart failure, and united had chest pain and malignant ventricular arrhythmias. The ejection fraction on radionuclide ventriculography was abnormal in 10 patients and normal (>50 percent) in 2 (Table 1) The average ejection fraction was 34 [+ or -] 12 percent (range, 11 to 57 percent) Four patients had a definite febrile fllnes before the assault of cardiac symptoms. Eight patients underwent left cardiac catheterization and coronary arteriography; normal coronary anatomy was demonstrated in all eight patients. In four patients aged 18 to 28 years, coronary arteriography was not performed. Five patients with a grave probability of myocarditis formed a superintend group; 1 was a female patient, and 4 were men with a mean age of 32 [+ or -] 15 years (range, 15 to 54 years). single of the patients had a long-standing history of congestive heart failure, and endomyocardial biopsy was nondiagnostic for myocarditis; single in kind had a congenital complete heart obstruct one patient was treated for atrial flirt one had a sinus tachycardia without symptoms of congestive heart failure, and single in kind patient had a coronary artery fistula.

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All bring under rules underwent myosin-specific monoclonal antibody imaging. Antimyosin antibody (Myoscint; Centocor Inc.) was supplied as a sterile nonpyrogenic solution containing 05 mg of R11D10 Fab DTPA, which is a mouse monoclonal antibody fragment that binds specifically to myosin. Antimyosin is radiolabeled by dint of the addition of sterile 111 In chloride. brace millicuries of 111 In were diluted to 10 ml of dimensions and administered intravenously by moderate injection. Planar imaging was performed 48 h later using a gamma camera (General Electric Maxi Camera 400) Three views were obtained (anterior, 45 [degrees] left anterior oblique, and 70 [degrees] left anterior oblique) using a 128 x 128 matrix for 10 min by means of view. Both photopeaks of 111 In (173 keV and 247 keV) were used with 20 percent efficacy windows. Images were evaluated for the neighborhood or absence of tracer uptake; a heart-to-lung (H/L) ratio was used to quantify tracer uptake;[4] the unprocess anterior projection was used to adjust a region of interest in the myocardium and a region of interest in each lung Average accounts per pixel in the myocardium were divided by way of the average counts per pixel in each lung to obtain the H/L ratio. An H/L ratio greater than 16 was considered abnormal.[4]

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