Clinical value of studies with radioiodinated heptadecanoic acid in patients with coronary artery disease

The results described in the literature of myocardial scintigraphy with radioiodinated heptadecanoic acid (IHDA) to detect coronary stenoses are contradictory. In the present study, IHDA scintigraphy was performed in nine control subjects and 67 patients with coronary artery disease. The acquisition time was 75 min and background correction was not applied. The time-activity curves of regions of interest were analyzed by curve fitting with a monoexponential plus constant. Two parameters were used: the halftime value of the monoexponential (T1/2 in min) and the ratio of the amplitude (A) of the monoexponential and the total activity at time t = 0 (amplitude + constant = A + C): A/A + C as a percentage. Based on the control group, a region of normal T1/2 values and A/A + C ratios was defined, for each calculated T1/2-A/A + C pair the probability of originating from a normal region was calculated. The value of the IHDA test, using the index of merit (sensitivity + specificity-100%), increased in the patient group without MI with the severity of the stenosis (21%, 24% and 47% for stenoses greater than or equal to 75%, greater than or equal to 90% and greater than or equal to 99%). In patients with MI, only small positive values in regions of non-infarct-related vessels were found (-1%-16%). It is concluded that the value of the IHDA test to detect stenoses of coronary arteries is too low to apply this test in clinical practice. However, a new type of analysis is offered, based on curve fitting of individual pixels.(ABSTRACT TRUNCATED AT 250 WORDS)