Fractional Flow Reserve as a Standard of Reference for Ischemia Early After ST Elevation Myocardial Infarction

The purpose of the present study was to assess the value of the fractional flow reserve (FFR) of the infarct-related artery (IRA) early after ST elevation myocardial infarction (STEMI) in detecting reversible ischemia.

Single photon emission computed tomography (SPECT) at rest and after dipyridamole stress, and within 24 hour FFR of the IRA was performed on 69 patients 3 to 7 days after STEMI. FFR was 0.80 or less in 61 (88.4%) of them. In these patients, percutaneous coronary intervention (PCI) was performed, and a second SPECT study was repeated within 14 days.

SPECT showed reversible ischemia in 36 (59%) of these 61 patients, and converted to negative in 29 of them. Thus, the SPECT results of these 29 patients were defined as true positive before angioplasty and true negative after angioplasty. Considering the true-positive and true-negative SPECT results as the gold standard, the sensitivity, specificity, and positive and negative predictive values of the FFR of 0.80 or less compared to this gold standard were 96.7%, 100%, 100%, and 96.6%, respectively (ĸ = 0.97, P < 0.001).

In the early phase after STEMI, the reliability of FFR to determine residual ischemia in the IRA is very high in those patients with true-positive SPECT before and true-negative SPECT after PCI.