Antimyosin antibody cardiac imaging: Its role in the diagnois of myocarditis

Abstract

Right ventricular endomyocardial biopsy currently remains the procedure of choice for identifying patients with symptomatic heart failure due to myocarditis from the larger population with idiopathic dilated cardiomyopathy. Despite its specificity, the sensitivity of right ventricular biopsy remains uncertain because of the focal or multifocal nature of the disease. Because myocyte necrosis is an obligate component of myocarditis, the use of indium-111 antimyosin imaging was evaluated in 82 patients with suspected myocarditis. Seventy-four patients had dilated cardiomyopathy of less than 1 year's duration (mean left ventricular ejection fraction 0.30 +/- 0.02); eight patients had normal left ventricular function (mean ejection fraction 0.59 +/- 0.03). Symptoms at presentation included congestive heart failure (92%), chest pain mimicking myocardial infarction (6%) and life-threatening ventricular tachyarrhythmias (2%). All patients underwent planar and single photon emission computed tomographic (SPECT) cardiac imaging after injection of indium-111-labeled antimyosin antibody fragments and right ventricular biopsy within 48 h of imaging. Antimyosin images were interpreted as either abnormal or normal and correlated with biopsy results. On the basis of the right ventricular histologic examination, the sensitivity of antimyosin imaging was 83%, specificity 53% and predictive value of a normal scan 92%. Improvement in left ventricular function occurred within 6 months of treatment in 54% of patients with an abnormal antimyosin scan compared with 18% of those with a normal scan (p less than 0.01). Antimyosin cardiac imaging may be useful for the initial evaluation of patients with dilated and nondilated cardiomyopathy and clinically suspected myocarditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Normal Post-Race Antimyosin Myocardial Scintigraphy in Asymptomatic Marathon Runners with Elevated Serum Creatine Kinase MB Isoenzyme and Troponin T Levels

“…Rather than attempting en domyocardial biopsies in asymptomatic marathon run ners, we chose to perform post-race quantitative antimyo sin myocardial imaging in which cardiac myocytes with damaged sarcolemmal membranes show specific binding of monoclonal antibody to exposed intracellular myosin [28,29]. Such antimyosin imaging has an established role in the evaluation of cardiac muscle damage in clinical conditions including myocarditis [30,31], cardiac trans plantation rejecton [32], drug-induced myocardial cell necrosis [15,33] and Lyme carditis [34].…”

Myocarditis

“…Unlike gallium 67 , which detects the extent of myocardial inflammation, antimyosin cardiac uptake reflects the extent of myocyte necrosis. Dec et al 92 evaluated the utility of antimyosin imaging in a large cohort of patients with clinically suspected myocarditis. On the basis of EMB, antimyosin uptake was found to be highly sensitive (83%) but only moderately specific (53%) for detecting myocardial necrosis.…”

Myocarditis Masquerading as Ischemic Heart Disease: The Diagnostic Utility of Antimγosin Imaging

“…Indium-labelled mono clonal antimyosin scanning has been found to be highly specific for the detection of myocar dial necrosis [7] and has demonstrated a high degree of accuracy in the setting of acute myo cardial infarction [8]. In addition to the focal uptake associated with myocardial infarction, a generalized pattern of antimyosin uptake has been detected in the presence of myocar ditis [9][10][11]. This diffuse pattern may help to differentiate myocarditis from myocardial in farction.…”