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Measurement of myocardium at risk by technetium-99m sestamibi: correlation with coronary angiography
K C Huber1, J F Bresnahan, D R Bresnahan
1Department of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905.
Insights
Coronary angiography estimates myocardial risk in acute myocardial infarction but has limited accuracy for individual patients. Tomographic perfusion imaging with technetium-99m sestamibi offers a more precise measurement of myocardium at risk.
Area of Science:
- Cardiology
- Nuclear Medicine
- Radiology
Background:
- Tomographic perfusion imaging using technetium-99m sestamibi (RP-30A) accurately quantifies myocardium at risk in acute myocardial infarction.
- Coronary angiography is a standard diagnostic tool, but its ability to predict the extent of myocardial damage requires further evaluation.
Purpose of the Study:
- To assess the accuracy of coronary angiography in predicting the percentage of left ventricular myocardium at risk during acute myocardial infarction.
- To compare angiographic estimates with myocardial perfusion imaging measurements in individual patients.
Main Methods:
- Twenty-one patients with their first acute myocardial infarction underwent coronary angiography.
- Two experienced angiographers provided a blinded "best estimate" of myocardium at risk using multiple angiographic variables.
- Myocardium at risk was measured using tomographic perfusion imaging with technetium-99m sestamibi.
Main Results:
- The mean angiographic best estimate showed a strong correlation with technetium-99m sestamibi measurements in groups of patients (r = 0.89, p < 0.0001).
- However, coronary angiography significantly overestimated myocardium at risk (p < 0.002) with a large standard error of estimate (8.6% of the left ventricle).
- Correlations were weaker when analyzing anterior or inferior infarcts separately, and individual patient predictions were limited, especially in inferior infarcts.
Conclusions:
- While coronary angiography provides a useful group-level correlation for myocardium at risk, its predictive ability for individual patients with acute myocardial infarction is limited.
- Tomographic perfusion imaging with technetium-99m sestamibi remains a more precise method for assessing the extent of myocardium at risk.
Abstract:
Previous studies have shown that tomographic perfusion imaging with technetium-99m sestamibi (RP-30A) can accurately measure the myocardium at risk during acute myocardial infarction. The ability of coronary angiography to predict the wide variability in myocardium at risk was studied in 21 patients with their first acute myocardial infarction. In blinded fashion, two experienced angiographers provided an overall "best estimate" of the percent of left ventricular myocardium at risk considering multiple angiographic variables--infarct-related artery, location of stenosis (proximal or nonproximal), vessel diameter, length, territory and the number and size of proximal branches and collateral vessels. Many of these individual variables showed a significant association with myocardium at risk. The most important angiographic variable was the mean best estimate of the two angiographers (r = 0.89, p less than 0.0001). However, the SEE was large (8.6% of the left ventricle) and angiography significantly (p less than 0.002) overestimated myocardium at risk. When patients with an anterior or an inferior infarct were considered separately, the angiographic best estimate had a weaker correlation with myocardium at risk measured by technetium-99m sestamibi in patients in both groups (anterior infarction r = 0.65, p = 0.04; inferior infarction r = 0.65, p = 0.04. Seven patients with an inferior infarct and myocardium at risk ranging from 7% to 32% of the left ventricle had identical angiographic best estimates. Although angiographic estimates correlate closely with measurements of myocardium at risk in groups of patients, their ability to predict the myocardium at risk in individual patients is limited.