EXERCISE BETA-METHYL IODOPHENYL PENTADECANOIC ACID (BMIPP) AND RESTING THALIUM DELAYED SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY (SPECT) IN THE ASSESSMENT OF ISCHEMIA AND VIABILITY

To clarify the significance of exercise BMIPP (beta-methyl iodophenyl pentadecanoic acid) and resting Tl delayed single photon emission comp uted tomography (SPECT) in the assessment of ischemia and viability, w e studied maximal exercise-loading BMIPP SPECT following rest-injected Tl 3 h SPECT in 11 control subjects, 20 patients with effort angina a nd 38 patients with old myocardial infarction. The left ventricular wa ll on ECT was divided into 9 segments. BMIPP and Tl uptake were scored as 0=normal, 1=reduced, 2=severely reduced, or 3=absent. Discordance was defined as when segments with a reduced BMIPP uptake had a better resting Tl uptake. Significant coronary artery stenosis was defined as stenosis of 75% or greater on coronary arteriogram. Left ventricular wall motion was assessed as either normokinesis, hypokinesis, severe h ypokinesis, akinesis or dyskinesis on left ventriculogram. When discor dance was considered to be a marker of ischemia, the sensitivity and s pecificity in effort angina and control subjects were 95.2% and 84.6% for patients and 83.9% and 94.4% for diseased vessels, respectively. T here were no differences between the sensitivity and specificity in le ft anterior descending artery (LAD), left circumflex artery (LCx) and right coronary artery (RCA) lesions (83.3%, 95.5% in LAD, 83.3%, 95.5% in LCx, 85.7%, 92.6% in RCA, respectively). All of the patients with old myocardial infarction had reduced exercise BMIPP uptake in infarct ed regions. In old myocardial infarction, 35 patients had segments wit h discordant uptake. Discordance was observed in 75 (91.5%) of 82 segm ents with hypokinesis, and in 24 (92.3%) of 26 segments with severe hy pokinesis. Even among the 36 segments with akinesis or dyskinesis, 25 (69.0%) had discordant uptake. When discordance in the infarcted regio n was considered to be a marker of viability, regions with severe asyn ergy showed a high possibility of viability. Thus, discordant uptake o n exercise BMIPP and resting Tl delayed SPECT may be a useful marker o f ischemia in effort angina and of viability in old myocardial infarct ion.