Agreement between iFR and FFR in staged follow-up evaluation of non-culprit stenoses after ST-segment elevation myocardial infarction (iSTEMI substudy)

• BACKGROUND: Classification agreement between instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) is approximately 80% in stable patients. It was recently shown that FFR guidance, as compared to iFR guidance, was associated with a higher risk of subsequent revascularization among patients with non- ST-segment elevation myocardial infarction. The classification agreement, and the impact of time interval, between iFR and FFR in the assessment of non-culprit lesions after recent ST-segment elevation myocardial infarction (STEMI) has not been described.METHODS: The iSTEMI study assessed agreement between iFR across non-culprit stenoses at the index procedure in patients with STEMI versus iFR and FFR at a follow-up angiography. The interval between STEMI and follow-up evaluation was at the discretion of the treating physicians. In this substudy, classification agreement between follow-up iFR and follow-up FFR was evaluated within groups defined according to follow-up time point after STEMI, i.e., <5days, 5-15days, and16 days. iFR<0.90 and FFR0.80 were considered hemodynamically significant.RESULTS: Among 120 patients with 157 non-culprit stenoses, follow-up iFR and FFR was available in 112 patients with 146 non-culprit stenoses. Median follow-up interval was 16 days (IQR 5-32 days). The overall classification agreement was 84%. With follow-up<5days after STEMI, there was classification agreement between iFR and FFR was in 27 of 35 (77%) non-culprit stenoses. With follow-up 5-15 after STEMI, there was classification agreement in 33 of 38 (86%) non-culprit stenoses. With follow-up 16 days after STEMI, there was classification agreement in 63 of 73 (86%) non-culprit stenoses. The observed differences in these proportions over time after STEMI were not statistically significant (<5versus5days, p¼0.19).CONCLUSION: Overall, classification agreement between iFR and FFR in the assessment of non-culprit lesions after STEMI was comparable to that observed in stable patients. Time interval between STEMI and follow-up evaluation may impact agreement between follow-up iFR and follow-up FFR, although the observed differences were not statistically significant.

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MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kardiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cardiac and Cardiovascular Systems (hsv//eng)

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