Identification of left ventricular thrombi in man using indium-111-labeled autologous platelets. A preliminary report.

Abstract

111In bound to 8-hydroxyquinoline can be used to label platelets without impairing their ability to participate in active thrombosis. Intracardiac thrombi were identified using 111In platelet scintigraphy. Patients (29) were studied. Twenty-one had discrete left ventricular aneurysms (group 1). The remaining 8 patients (group 2) had normal or minimally narrowed coronary vessels (< 50%) and a global ejection fraction of 54 .+-. 14% without segmental dysfunction on contrast ventriculography. Six of the 8 patients with insignificant coronary disease had severe mitral valve disease requiring surgery. Each i.v. injection contained 3.4 .+-. 1.6 .times. 106 platelets labeled in a solution of acid citrate dextrose and saline (1:7, pH 6.5) with 454 .+-. 144 .mu.Ci 111In complexed to 8-hydroxyquinoline with a final labeling efficiency of 67 .+-. 17%. Platelet recovery at 15 min was 37.8 .+-. 14.5% (n = 15). Imaging was performed in the anterior, left anterior oblique 45.degree. and left lateral oblique 45.degree. and left lateral views (the right anterior oblique 45.degree. view was included in all except patients 1-5 in group 1) on the day of injection and at 1-2 day intervals for a maximum of 8 days. In group 1, nine patients had abnormal areas of increased activity within the left ventricle. Four required aneurysmectomy and had left ventricular thrombi; a 5th died and at autopsy evidence of a thrombus was found. In 4 patients (the only patients in whom these data were obtained), surface thrombus 111In activity was at least 9.7 times greater than that of blood, noninvolved myocardium and deeper aspects of the thrombus. Twelve patients with aneurysms had normal scintiphotos. Six required aneurysmectomy and were negative for thrombi. All the patients in group 2 had negative platelet scintiphotos. The 6 patients who required mitral valve replacement had no thrombi at surgery. The diagnostic accuracy of platelet scintigraphy (both groups) in the 17 patients in whom surgical or postmortem confirmation of thrombi could be obtained, 5 of whom had positive scintiphotos, was 100%. 111In platelet scintigraphy promises to be a reliable method for the identification of left ventricular thrombi.