Early dipyridamole stress myocardial SPECT to detect residual stenosis of infarct related artery: comparison with coronary angiography and fractional flow reserve.

BACKGROUND: The detection of residual stenosis of infarct related artery (IRA) at early stage after acute myocardial infarction (AMI) is crucial in clinical decision making for interventional revascularization. The aim of this study was to evaluate the relevancy of early dipyridamole stress myocardial SPECT to detect functionally and luminologically significant residual stenosis of IRA after AMI. METHODS: Twenty five consecutive patients (M:F=19:6, age: 56±13yrs) with AMI underwent SPECT and coronary angiography within 5 days of the attack. Infarct related arteries with FFR < 0.75 and diameter stenosis (DST) >70% were regarded to have functionally and morphologically significant residual stenosis. Reversible perfusion defect was defined if there was improvement of the perfusion score more than one grade in infarct segments on rest images of SPECT compared with stress images. RESULTS: Mean FFR and DST were 0.76±0.14 and 74±15%. SPECT showed no significant correlation with both FFR and DST with Kendall’s coefficiency of 0.28 (p=0.05) and 0.13 (p=0.35). The sensitivity and specificity of SPECT to detect functionally and morphologically significant residual stenosis were 92%, 31% and 83%, 29%. CONCLUSION: The early dipyridamole stress myocardial SPECT after AMI does not seem to be a useful non-invasive test for the detection of functionally and luminologically significant residual stenosis of IRA.