Histograms of pressure wire FFR values for FFRMC and FFRPW Histograms of pressure wire FFR values for FFRMC and FFRPW. These reveal a typical unimodal distribution with predominantly intermediate FFR values. Histograms of pressure wire FFR values for FFRMC and FFRPW. These reveal a typical unimodal distribution with predominantly intermediate FFR values. The black lines indicate median values. FFRMC, microcatheter fractional flow reserve; FFRPW, pressure wire fractional flow reserve. Henry Seligman et al. Open Heart 2019;6:e000971 ©2019 by British Cardiovascular Society