Gilbert Wijntjens

The IMPACT Study (Influence of Sensor-Equipped Microcatheters on Coronary Hemodynamics and the Accuracy of Physiological Indices of Functional Stenosis Severity)

Background—The Navvus pressure sensor–equipped microcatheter allows to measure functional stenosis severity over a work-horse guidewire and is used as a more feasible alternative to regular sensor-equipped wires. However, Navvus is larger in diameter than contemporary sensor-equipped guidewires and may, thereby, influence functional measurements. The present study evaluates the hemodynamic influence of the Navvus microcatheter. Methods and Results—In patients with intermediate coronary stenosis, coronary pressure and flow velocity were measured using a dual sensor–equipped guidewire before and after introduction of Navvus. Patients were randomized to microcatheter-first or guidewire-first measurement. The primary end point was the difference in hyperemic stenosis resistance index between measurements before and after introduction of Navvus. Measurements were completed in 28 patients (28 stenoses). Mean hyperemic stenosis resistance was 0.37±0.19 Hg/cm/s for wire-only assessment and 0.48±0.26 Hg/cm/s after Navvus introduction (P<0.001). Bland–Altman analysis documented a mean bias of +0.11 Hg/cm/s (limits of agreement: −0.13 to 0.36), proportional to mean hyperemic stenosis resistance (Spearman &rgr; =0.61; P=0.001). Passing–Bablok analysis revealed absence of a constant difference but significant proportional difference between the methods. Mean fractional flow reserve was 0.86±0.06 for wire-only assessment and 0.82±0.07 after Navvus introduction (P<0.001). Bland–Altman analysis documented a mean bias of −0.033 (limits of agreement: −0.09 to 0.03), proportional to mean fractional flow reserve (Spearman &rgr; =0.40; P=0.036). Passing–Bablok analysis revealed significant constant and proportional differences between methods. Similar results were documented for resting indices of stenosis severity. Conclusions—Introduction of the Navvus microcatheter leads to clinically relevant stenosis severity overestimation in intermediate stenosis.

Assessing the Haemodynamic Impact of Coronary Artery Stenoses: Intracoronary Flow Versus Pressure Measurements

Fractional flow reserve (FFR)-guided percutaneous coronary intervention results in better long-term clinical outcomes compared with coronary angiography alone in intermediate stenoses in stable coronary artery disease (CAD). Coronary physiology measurements have emerged for clinical decision making in interventional cardiology, but the focus lies mainly on epicardial vessels rather than the impact of these stenoses on the myocardial microcirculation. The latter can be quantified by measuring the coronary flow reserve (CFR), a combined pressure and flow index with a strong ability to predict clinical outcomes in CAD. However, combined pressure-flow measurements show 30-40 % discordance despite similar diagnostic accuracy between FFR and CFR, which is explained by the effect of microvascular resistance on both indices. Both epicardial and microcirculatory involvement has been acknowledged in ischaemic heart disease, but clinical implementation remains difficult as it requires individual proficiency. The recent introduced pressure-only index instantaneous wave-free ratio, a resting adenosine-free stenosis assessment, led to a revival of interest in coronary physiology measurements. This review focuses on elaborating the coronary physiological parameters and potential of combined pressure-flow measurements in daily clinical practice.

INSTANTANEOUS WAVE-FREE RATIO SCOUT PULLBACK (IFR SCOUT) PRE-ANGIOPLASTY PREDICTS HEMODYNAMIC OUTCOME IN HUMANS WITH CORONARY ARTERY DISEASE: PRIMARY RESULTS OF INTERNATIONAL MULTICENTRE IFR GRADIENT REGISTRY

Background: In tandem and diffuse disease, offline analysis of continuous instantaneous wave-free ratio (iFR) pullback measurement has been demonstrated to accurately predict the physiological outcome of revascularization. However, the accuracy of the real-time online analysis approach (iFR Scout)

Prognostic implications of instantaneous wave-free ratio (iFR) and resting distal-to-aortic pressure ratio (Pd/Pa) compared with fractional flow reserve (FFR). A 10-year follow-up study after deferral of revascularization

iFR and Pd/Pa are novel indices introduced to enhance adoption of physiology-guided revascularization. Their absolute agreement with FFR is 80%, but both indices agree better with coronary flow reserve (CFR) than FFR. Since CFR is a critical determinant of myocardial ischemia and clinical outcome,