Accuracy of fractional flow reserve during acute myocardial infarction

This commentary refers to ‘Fractional flow reserve in clinical practice: from wire-based invasive measurement to image-based computation’, by S. Tu et al., doi:10.1093/eurheartj/ehz918. In their recent excellent review, Tu et al.1 suggested that imaging-derived physiology is a better test than fractional flow reserve (FFR) for the functional assessment of non-culprit lesions in the setting of acute myocardial infarction (MI). They suggested that the accuracy of FFR in the setting of acute MI may not be correct due to disturbed microvascular function; however, their concern is based on older, poorly conducted studies. Recently, several well-designed studies have shown that both the FFR and instantaneous wave-free ratio (iFR) can be reliable tools for the functional assessment of non-culprit lesions in patients with acute MI.2–4 In a well-conducted study by Ntalianis et al.,4 101 patients with acute MI [n = 75 with ST-segment elevation MI (STEMI) and n = 26 with non-STEMI] were prospectively recruited. The FFR measurements in 112 non-culprit stenoses were obtained immediately after percutaneous intervention of the culprit stenosis and were repeated 35 ± 4 days later. The FFR value of the non-culprit stenoses did not change between the acute and follow-up measurements (0.77 ± 0.13 vs. 0.77 ± 0.13, respectively, P = non-significant). Similarly, in the WAVE study, paired iFR and FFR measurements were conducted on 66 non-culprit lesions in 50 patients with STEMI.3 The iFR and FFR values of the non-culprit lesions did not change significantly between the index and staged procedures. In addition, several well-designed studies have shown that the microcirculation does not affect the non-infarcted myocardium during MI.4