Analysis of Ischemia Patterns in Patients with Unstable Angina who Respond Favourably to Initial Medical Treatmen. Tc-99 Ventriculography and Perfusion Imaging with Tc-99 Sest Mibi Spect

pp 173-178

Abstract

Background and objectives

The aim of this study was to determine the different ischemic patterns in patients admitted to the coronary care unit with diagnosis of unstable angina, who responded favourably to initial medical treatment by means of Tc-99 ventriculography and perfusion imaging with Tc-99 Sesta Mibi Spect.

Methods and results

Eighteen patients were included and divided into three groups according to their symptoms. Group A: progressive angina (n = 8), increase in frequency of symptoms or decrease of functional class within the last two months in patients previously stable. Group B: recenton set angina (n = 7), chest pain initiated within the last three months before admission. Group C: Prolonged angina (n = 3), chest pain lasting at least fifteen minutes.Both Tc-99radionuclide ventriculography at rest, exercise, hyperventilation and cold test, and myocardial perfusion imaging with Tc-99 Sesta Mibi Spect at rest, exercise or dipyridamole infusion were performed in all patients 72 hours after the last episode of angina.Patients older than 75 years, those with acute myocardial infarction and those who remained unstable were excluded. A total of 108 segments were analized by Tc-99 radionuclide ventriculography and 450 were analized by Mibi Spect. The findings of stunning, coronary artery spasm, hybernation, ischemia and necrosis in each group were the following. Group A: stunning50%, coronary artery spasm 25%, hybernation 25%, ischemia 50%, necrosis 25%. Ischemia was detected in18.7% of the segments and coronary artery spasm in 2% of the segments by ventriculography. In Spect images 16% of the segments were ischemic.Group B: stunning50%,coronary artery spasm 25 %, hybernation 0%, ischemia 57%, necrosis 0%. Ischemia was found in 9.2%and coronary artery spasm in 11.9% of the segments by ventriculography. On Spects images 13% of the segments were ischemic. Group C: stunning 33%, coronary artery spasm 0%, hybernation 0%, ischemia 33%, necrosis 0%. Ischemia was present in 16% of the segments by ventriculography. The Spect images showed that 12% of the segments were ischemic. There was no significant differences between the three groups with respect to rest and exercise ejection fraction.

Conclusions

The presente of ischemia in their population is considerable. However, the amount of myocardium at risk is low as judged by the few hypoperfused segments and the high ejection fraction observed.