Impact of core laboratory assessment on treatment decisions and clinical outcomes using combined fractional flow reserve and coronary flow reserve measurements - DEFINE-FLOW core laboratory sub-study.

Objective: The role of combined FFR/CFR measurements in decision-making on coronary revascularization remains unclear. DEFINE-FLOW prospectively assessed the relationship of FFR/CFR agreement with 2-year major adverse cardiac event (MACE) and target vessel failure (TVF) rates, and uniquely included core-laboratory analysis of all pressure and flow tracings. We aimed to document the impact of core-laboratory analysis on lesion classification, and the relationship between core-laboratory fractional flow reserve (FFR) and coronary flow reserve (CFR) values with clinical outcomes and angina burden during follow-up.

Usefulness of Proximal Coronary Wave Speed for Wave Intensity Analysis in Diseased Coronary Vessels.

Wave speed is needed to separate net wave intensity into forward and backward traveling components. However, wave speed in diseased coronary arteries cannot be assessed from hemodynamic measurements obtained distal to a stenosis. Wave speed inherently depends on arterial wall properties which should be similar proximal and distal to a stenosis.

Distal Evaluation of Functional performance with Intravascular sensors to assess the Narrowing Effect-combined pressure and Doppler FLOW velocity measurements (DEFINE-FLOW) trial: Rationale and trial design.

Background: It remains uncertain if invasive coronary physiology beyond fractional flow reserve (FFR) can refine lesion selection for revascularization or provide additional prognostic value. Coronary flow reserve (CFR) equals the ratio of hyperemic to baseline flow velocity and has a wealth of invasive and noninvasive data supporting its validity. Because of fundamental physiologic relationships, binary classification of FFR and CFR disagrees in approximately 30%-40% of cases.

Individual Lesion-Level Meta-Analysis Comparing Various Doses of Intracoronary Bolus Injection of Adenosine With Intravenous Administration of Adenosine for Fractional Flow Reserve Assessment.

Background: Intravenous infusion of adenosine is considered standard practice for fractional flow reserve (FFR) assessment but is associated with adverse side-effects and is time-consuming. Intracoronary bolus injection of adenosine is better tolerated by patients, cheaper, and less time-consuming. However, current literature remains fragmented and modestly sized regarding the equivalence of intracoronary versus intravenous adenosine.

Multidirectional wall shear stress promotes advanced coronary plaque development: comparing five shear stress metrics.

Aims: Atherosclerotic plaque development has been associated with wall shear stress (WSS). However, the multidirectionality of blood flow, and thus of WSS, is rarely taken into account. The purpose of this study was to comprehensively compare five metrics that describe (multidirectional) WSS behaviour and assess how WSS multidirectionality affects coronary plaque initiation and progression.

Discordance between pressure drift after wire pullback and intracoronary distal pressure offset affects stenosis physiology appraisal.

Background: Drift is a well-known issue affecting intracoronary pressure measurements. A small pressure offset at the end of the procedure is generally considered acceptable, while repeat assessment is advised for drift exceeding ±2 mmHg. This practice implies that drift assessed after wire pullback equals that at the time of stenosis appraisal, but this assumption has not been systematically investigated.

Influence of increased heart rate and aortic pressure on resting indices of functional coronary stenosis severity.

Unlabelled: Baseline assessment of functional stenosis severity has been proposed as a practical alternative to hyperemic indices. However, intact autoregulation mechanisms may affect intracoronary hemodynamics. The aim of this study was to investigate the effect of changes in aortic pressure (Pa) and heart rate (HR) on baseline coronary hemodynamics and functional stenosis assessment.

Temporal dissociation between the minimal distal-to-aortic pressure ratio and peak hyperemia during intravenous adenosine infusion.

The present study sought to compare the temporal relation between maximal coronary flow (peak hyperemia) and minimal coronary-to-aortic pressure ratio (P/P) for intracoronary (IC) and intravenous (IV) adenosine administration. Peak hyperemia is assumed to coincide with the minimal P/P value. However, this has not been confirmed for systemic hemodynamic variations during IV adenosine infusion.

Transcatheter Replacement of Stenotic Aortic Valve Normalizes Cardiac-Coronary Interaction by Restoration of Systolic Coronary Flow Dynamics as Assessed by Wave Intensity Analysis.

Background: Aortic valve stenosis (AS) can cause angina despite unobstructed coronary arteries, which may be related to increased compression of the intramural microcirculation, especially at the subendocardium. We assessed coronary wave intensity and phasic flow velocity patterns to unravel changes in cardiac-coronary interaction because of transcatheter aortic valve implantation (TAVI).

Methods And Results: Intracoronary pressure and flow velocity were measured at rest and maximal hyperemia in undiseased vessels in 15 patients with AS before and after TAVI and in 12 control patients.