Altered cardiac‐coronary coupling relates to abnormal fractional flow reserve without flow limitation after percutaneous coronary interventions

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  FIGURE 1. Visual Abstract Residual low fractional flow reserve (FFR) despite normal hyperemic stenosis resistance (hSR) following percutaneous coronary intervention (PCI) does not associate with impaired hyperemic flow (hAPV, hyperemic average peak velocity) or flow augmentation capacity (CFVR, coronary flow velocity reserve). As can be appreciated from the two example cases, the case on the right had similar distal coronary pressure (Pd) and numerically higher hAPV as well as lower hyperemic microvascular resistance (hMR) despite having a FFR of 0.70. This case has relatively lower peak backward expansion wave (BEW) and forward compression wave (FCW), which do not coincide with impaired perfusion parameters. Initial fast decompression of coronary circulation marked by initially fast decay of Pd creates an earlier and impactful microvascular suction, ensuring quicker diastolic filling, which subsequently slows down the pressure decay, leading to higher Pd during mid‐to late diastole, that relates to a higher FFR. Initial slow decompression of coronary circulation marked by initially slow decay of Pd creates a later and weaker microvascular suction, with delayed diastolic filling, which…

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  FIGURE 2. Residual low FFR after PCI is associated with lower hyperemic accelerating wave energy flux during systole and diastole despite comparable mean velocity characteristics highlighting the distinct phasic differences in cardiac‐coronary coupling (data is expressed as mean ± SD).

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  FIGURE 3. FFR—hSR discordance is not primarily associated with formulation difference and use of ∆P (Pa – Pd) versus Pd/Pa, or an increased flow (velocity). There were discordant and concordant cases with similar ∆P and similar hAPV within the same hSR range.