ASSESSMENT OF MYOCARDIAL PERFUSION AND FUNCTION USING GATED METHOXY-ISOBUTYL-ISONITRILE SCINTIGRAPHY TO DETECT RESTENOSIS AFTER CORONARY ANGIOPLASTY

Background: Technetium-99m-methoxy-isobutyl-isonitrile (MIBI) has been shown to be a useful perfusion agent, and its improved imaging charac teristics also allow evaluation of myocardial function. We evaluated t he use of gated MIBI scintigraphy in patients undergoing percutaneous transluminal coronary angioplasty to show improvements in myocardial p erfusion and function and to detect restenosis. Methods: Gated MIBI sc intigraphy was performed in a preliminary study in 25 patients before angioplasty. Twenty-one patients who had undergone a successful proced ure were re-examined 3 months later. Myocardial perfusion was evaluate d and function measured using myocardial profiles along four axes. Res ults: Before angioplasty, 18 out of 21 patients had a reversible perfu sion defect, and computer analysis of fractional shortening showed 19 out of 21 had abnormalities of left ventricular function during exerci se. Only 11 out of 21 had a positive stress test. Mean global fraction al shortening before angioplasty was 27.3% at rest and 26.6% during ex ercise (not significant). After angioplasty, left ventricular function was improved during exercise, with global fractional shortening incre asing from 26.6% to 32.7% (P<0.001). Repeat angiography was performed in 16 patients. Lesions in four patients had restenosed, in 11 they ha d not, and in one a different artery was occluded. Three of the four p atients with restenosed lesions were identified using repeat perfusion imaging, and all four from abnormalities in left ventricular function . An abnormality in a new region was detected using both methods in th e patient with the new occlusion. Normal perfusion and function were f ound in nine of the 11 patients without restenosed lesions. Two patien ts continued to have a positive stress test: one with a restenosed les ion and one with new disease. Conclusion: Dual assessment with gated M IBI scintigraphy provides useful data in patients undergoing angioplas ty and may help in the selection of patients for repeat angiography.