BACKGROUND Pressure measurement for the duration of the wave-free period (WFP) is considered essential for resting-state physiological assessment of coronary stenosis severity using the instantaneous wave-free ratio (iFR). OBJECTIVES The aim of this study was to compare other diastolic resting indexes to iFR. METHODS In the population of the VERIFY2 (Pd/Pa vs iFR in an Unselected Population Referred for Invasive Angiography) study, iFR calculated by proprietary software (Volcano Harvest, Volcano Corporation, Rancho Cordova, California) was compared with the ratio of resting distal coronary pressure and aortic pressure during the complete duration of diastole (dPR), 25% to 75% of diastole (dPR25-75), and midpoint of diastole (dPRmid), along with Matlab calculated iFR (iFRmatlab) and iFR-like indexes shortening the length of the WFP by 50 and 100 ms (iFR-50ms and iFR-100ms), respectively. Mutual differences, Spearman correlations, area under the curve values from receiver-operating characteristic analyses, and diagnostic performance with respect to iFR and fractional flow reserve (FFR) were calculated for all indexes. RESULTS Median iFR in 197 patients with 257 vessels was 0.91 with an interquartile range of 0.87 to 0.95. The mutual differences (± SD) with iFR were 0.006 ± 0.011 (dPR), 0.001 ± 0.007 (dPR25-75), 0.001 ± 0.008 (dPRmid), 0.005 ± 0.009 (iFRmatlab), 0.003 ± 0.008 (iFR-50ms), and 0.001 ± 0.009 (iFR-100ms). Correlations for all indexes with iFR were >0.99 (p < 0.001 for all). Area under the curve values for predicting iFR were >0.99 for all indexes as well. Diagnostic accuracy compared with FFR was 76% to 77% for all indexes including iFR. CONCLUSIONS All diastolic resting indexes tested were identical to iFR, both numerically and with respect to their agreement with FFR. A numerically equal value to iFR can be determined without restriction to the WFP. Cutoff values, guidelines, and clinical recommendations for iFR can therefore be extended to these other indexes. (Pd/Pa vs iFR in an Unselected Population Referred for Invasive Angiography [VERIFY2]; NCT02377310).

中文翻译：

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不同舒张静息指数与 iFR 的比较

背景技术 无波期 (WFP) 期间的压力测量被认为对于使用瞬时无波比 (iFR) 的冠状动脉狭窄严重程度的静息状态生理评估是必不可少的。目的 本研究的目的是将其他舒张静息指数与 iFR 进行比较。方法 在 VERIFY2 研究的人群中（Pd/Pa 与 iFR 在非选定人群中进行侵入性血管造影）研究，通过专有软件（Volcano Harvest，Volcano Corporation，Rancho Cordova，California）计算的 iFR 与静息远端冠状动脉的比率进行比较。在整个舒张期 (dPR)、25% 至 75% 的舒张期 (dPR25-75) 和舒张期中点 (dPRmid) 期间的压力和主动脉压，连同 Matlab 计算的 iFR (iFRmatlab) 和类似 iFR 的索引，分别将 WFP 的长度缩短了 50 和 100 毫秒（iFR-50 毫秒和 iFR-100 毫秒）。计算所有指标的相互差异、Spearman 相关性、接受者操作特征分析的曲线下面积值以及 iFR 和血流储备分数 (FFR) 方面的诊断性能。结果 197 名患者的 257 条血管的中位 iFR 为 0.91，四分位间距为 0.87 至 0.95。与 iFR 的相互差异 (± SD) 为 0.006 ± 0.011 (dPR)、0.001 ± 0.007 (dPR25-75)、0.001 ± 0.008 (dPRmid)、0.005 ± 0.009 (iFRmatlab)、0.005 (iFRmatlab)、0.005 ms (dPR25-75) 0.001 ± 0.009 (iFR-100ms)。所有指标与 iFR 的相关性 >0.99（所有指标 p < 0.001）。对于所有指标，用于预测 iFR 的曲线值下面积也 >0.99。与 FFR 相比，包括 iFR 在内的所有指标的诊断准确性为 76% 至 77%。结论 测试的所有舒张静息指数在数值上和与 FFR 的一致性方面均与 iFR 相同。可以在不限制 WFP 的情况下确定与 iFR 数值相等的数值。因此，iFR 的临界值、指南和临床建议可以扩展到这些其他指标。（Pd/Pa 与 iFR 在未选择人群中进行侵入性血管造影 [VERIFY2]；NCT02377310）。因此，iFR 的临床建议可以扩展到这些其他指标。（Pd/Pa 与 iFR 在未选择人群中进行侵入性血管造影 [VERIFY2]；NCT02377310）。因此，iFR 的临床建议可以扩展到这些其他指标。（Pd/Pa 与 iFR 在未选择人群中进行侵入性血管造影 [VERIFY2]；NCT02377310）。