[Diagnosis of left ventricular aneurysm by exercise thallium-201 myocardial single photon emission computed tomography].

ABSTRACT

To diagnose and characterize post-infarction left ventricular aneurysms, we performed exercise thallium-201 myocardial single photon emission computed tomography (SPECT) combined with selective coronary angiography and left ventriculography. The subjects consisted of 79 patients with acute myocardial infarction; 42 with anteroseptal, three with both anterior and inferior, 29 with inferior and five with posterior infarction. Visual classification of ventricular wall morphology by either a horizontal or a vertical long-axis image was designed into convergent (C), parallel (P) and divergent (D) types, according to the interrelationship between either septal and lateral wall or anterior and inferior wall, respectively. This method was applied in post-stress and delayed images, and these patients were divided into five groups (Group A-E) in accordance with varying morphological types from the post-stress to the delayed as follows C-C (Group A, 36 patients), P-C (Group B, 8), P-P (Group C, 7), D-P (Group D, 5) and D-D (Group E, 23). A high incidence (21/23) of a left ventricular aneurysm by left ventriculography was recognized in Group E patients in comparison with other Groups. Provided that either Group D or E (all patients had anterior infarction) had left ventricular aneurysms, the diagnostic sensitivity, specificity and accuracy were 89%, 92% and 86%, respectively. Two of three patients with false negative diagnosis had only apical involvement. Furthermore, these two Groups had significantly larger defect scores as calculated by polar maps than did the other three Groups. When patients with anterior infarction with defect scores of 200 or greater were defined positive, the sensitivity, specificity and accuracy of ventricular aneurysms were 96%, 75% and 86%, respectively. One false negative case was apical infarction, and one of the two false positive cases were extensive anteroseptal infarction involving the apex. These results suggest that a left ventricular aneurysm which is important in predicting prognostic sequence could be diagnosed only by exercise SPECT, and that it could be characterized by extensive and severe apicoanterior infarction and a divergent-type ventricular wall arrangement on a post-stress SPECT image.