Non hyperemic pressure ratios in coronary physiology
Gottsegen György Országos Kardiológiai Intézet, Budapest
Lately, non-hyperemic pressure ratios (NHPR) measured “at rest” without the need for hyperemia as opposed to Fractional Flow Reserve (FFR) have taken to central stage in the realm of clinical intracoronary physiology. NHPR are claimed to be easier, quicker and less costly to measure than the gold standard FFR. At the same time, less hyperemia leads to lower diagnostic accuracy, and that of NHPR measured at rest remains only 80% compared to FFR. Two large-scale randomized clinical trials have shown that iFR is non-inferior to FFR. The present review summarizes and critically analyzes the theoretical basis of NHPR, highlights the limitations of these trials and discusses NHPR beyond iFR.