Hyperemic Stenosis Resistance Index for Evaluation of Functional Coronary Lesion Severity

Abstract

Background-Both coronary blood flow velocity reserve (CFVR) and myocardial fractional flow reserve (FFR) are used to evaluate the hemodynamic severity of coronary lesions. However, discordant results between CFVR and FFR have been observed in 25% to 30% of intermediate coronary lesions. An index of stenosis resistance based on a combination of intracoronary pressure and flow velocity may improve the assessment of functional coronary lesion severity. Methods and Results-Single photon emission computed tomography (SPECT) was performed in 151 patients with angina to determine reversible perfusion defects within one-week before cardiac catheterization. Coronary pressure and flow velocity was measured distal to 181 single coronary lesions with a mean diameter stenosis of 56% (range: 32% to 85%). Maximum hyperemia was induced by 15 to 20 g IC adenosine to determine CFVR, FFR, and the hyperemic stenosis resistance index (h-SRv), defined as the ratio of hyperemic stenosis pressure gradient (mean aorta pressure-mean distal pressure) and hyperemic average peak-flow velocity. Receiver-operating-characteristic curves of CFVR, FFR, and h-SRv were calculated to evaluate the predictive value for presence of reversible perfusion defects on SPECT with the use of the area under curve (AUC

Coronary Functional Tests in the Catheterization Laboratory – Pathophysiological and Clinical Relevance –

“…33 HMR represents the mean distal coronary pressure to mean distal flow velocity ratio during maximal hyperemia, 34 whereas HSR is defined as the ratio between the pressure drop across the stenosis and distal peak flow velocity during maximal hyperemia (Figure 2). 35 Of note, in 1 study, HSR was a more powerful predictor of reversible perfusion defects as compared with FFR or CFVR. 35 Furthermore, a recent study by van de Hoef et al 36 provided important insights into the role of HMR in the identification of ischemiainducing coronary stenoses by FFR.…”

“…35 Of note, in 1 study, HSR was a more powerful predictor of reversible perfusion defects as compared with FFR or CFVR. 35 Furthermore, a recent study by van de Hoef et al 36 provided important insights into the role of HMR in the identification of ischemiainducing coronary stenoses by FFR. They observed that the diagnostic accuracy for inducible ischemia on myocardial perfusion scans of a positive compared with a negative FFR was significantly higher only in the presence of a high HMR (at the 0.75 and 0.80 FFR cutoff).…”

“…They observed that the diagnostic accuracy for inducible ischemia on myocardial perfusion scans of a positive compared with a negative FFR was significantly higher only in the presence of a high HMR (at the 0.75 and 0.80 FFR cutoff). 34, 35 Notably, distal to corointermediate coronary stenoses (Figure 2). 30 For a FFR cutoff of 0.80, a predefined iFR value of 0.90 provided the optimal cutoff, with a classification match of 80%; when the originally validated 0.75 ischemic FFR cutoff was used as a reference comparison, the agreement between iFR and FFR increased to 88% with the optimal iFR cutoff being 0.85; when accounting for the known 0.75-0.80 FFR gray zone, the classification match between iFR and FFR increased to 93%.…”

Deleterious Effects of Cold Air Inhalation on Coronary Physiological Indices in Patients With Obstructive Coronary Artery Disease

“…Minimal MVR therefore excludes systolic compressive resistance and better informs vascular resistance, and has been shown not to be influenced by coronary artery stenosis severity 18. Trans‐stenotic pressure gradient (aortic pressure (P a )−P d ), P d /P a ratio, and epicardial stenosis resistance (P a −P d /average peak velocity)19 were also calculated as measures of stenosis severity. Epicardial stenosis resistance, defined as the ratio of the pressure drop across the stenosis to distal coronary flow velocity, normalizes the pressure drop for the magnitude of epicardial coronary flow velocity at which it was obtained, providing a more objective assessment of hemodynamic stenosis severity.…”

Characteristics of the flow velocity-pressure gradient relation in the assessment of stenoses: an in vitro study

“…Both the hyperaemic stenosis resistance (HSR) and dp v50 , which is derived from the diastolic flow velocity-pressure gradient (v-dp) relation, have been found to determine the haemodynamic significance of a coronary stenosis with a high accuracy. [3][4][5][6] Patients frequently have multiple stenoses in the same coronary artery. Compared with a single stenosis, multiple consecutive stenoses result in a greater reduction in maximal flow.…”