Comparison of pressure wire versus microcatheter for fractional flow reserve measurements: limitations of microcatheter-based measurements

We read with great interest the recent paper by Pouillot et al1, assessing the clinical impact of the new fractional flow reserve (FFR) microcatheter (Navvus™ MicroCatheter; ACIST Medical Systems, Inc., Eden Prairie, MN, USA). Seventy-seven consecutive patients were recruited into a prospective registry and had FFR evaluated by microcatheter (FFRMC) and by pressure wire (FFRW). The authors reported that the mean FFRW (0.83±0.08) was significantly higher than the mean FFRMC (0.80±0.10) (p=0.012) and that the Bland-Altman analysis showed a bias of –0.03±0.05 for lower FFRMC values compared to FFRW values. The Pearson’s correlation coefficient (r) between FFRW and FFRMC was 0.85 (p&...