Respiration-related variations in Pd/Pa ratio and fractional flow reserve in resting conditions and during intravenous adenosine administration.

Aims: We evaluated the occurrence and physiology of respiration-related beat-to-beat variations in resting Pd/Pa and FFR during intravenous adenosine administration, and its impact on clinical decision-making.

Methods And Results: Coronary pressure tracings in rest and at plateau hyperemia were analyzed in a total of 39 stenosis from 37 patients, and respiratory rate was calculated with ECG-derived respiration (EDR) in 26 stenoses from 26 patients. Beat-to-beat variations in FFR occurred in a cyclical fashion and were strongly correlated with respiratory rate (R  = 0.

Phasic flow patterns of right versus left coronary arteries in patients undergoing clinical physiological assessment.

Background: Coronary blood flow in humans is known to be predominantly diastolic. Small studies in animals and humans suggest that this is less pronounced or even reversed in the right coronary artery (RCA).

Aims: This study aimed to characterise the phasic patterns of coronary flow in the left versus right coronary arteries of patients undergoing invasive physiological assessment.

A prospective multicenter validation study for a novel angiography-derived physiological assessment software: Rationale and design of the radiographic imaging validation and evaluation for Angio-iFR (ReVEAL iFR) study.

Angiography-derived physiological assessment of coronary lesions has emerged as an alternative to wire-based assessment aiming at less-invasiveness and shorter procedural time as well as cost effectiveness in physiology-guided decision making. However, current available image-derived physiology software have limitations including the requirement of multiple projections and are time consuming. METHODS/DESIGN: The ReVEAL iFR (Radiographic imaging Validation and EvALuation for Angio-iFR) trial is a multicenter, multicontinental, validation study which aims to validate the diagnostic accuracy of the Angio-iFR medical software device (Philips, San Diego, US) in patients undergoing angiography for Chronic Coronary Syndrome (CCS).

Time course of coronary flow capacity impairment in ST-segment elevation myocardial infarction.

Background: Microvascular dysfunction in the setting of ST-elevated myocardial infarction (STEMI) plays an important role in long-term poor clinical outcome. Coronary flow reserve (CFR) is a well-established physiological parameter to interrogate the coronary microcirculation. Together with hyperaemic average peak flow velocity, CFR constitutes the coronary flow capacity (CFC), a validated risk stratification tool in ischaemic heart disease with significant prognostic value.

Acute alterations in glucose homeostasis impact coronary microvascular function in patients presenting with ST-segment elevation myocardial infarction.

Background: Microvascular dysfunction in the setting of ST-segment myocardial infarction (STEMI) is thought to be related to stress-related metabolic changes, including acute glucose intolerance. The aim of this study was to assess the relationship between admission glucose levels and microvascular function in non-diabetic STEMI patients.

Methods: 92 consecutive patients with a first anterior-wall STEMI treated with primary percutaneous coronary intervention (PPCI) were enrolled.

Artificial Intelligence for Aortic Pressure Waveform Analysis During Coronary Angiography: Machine Learning for Patient Safety.

Objectives: This study developed a neural network to perform automated pressure waveform analysis and allow real-time accurate identification of damping.

Background: Damping of aortic pressure during coronary angiography must be identified to avoid serious complications and make accurate coronary physiology measurements. There are currently no automated methods to do this, and so identification of damping requires constant monitoring, which is prone to human error.

Pressure-derived estimations of coronary flow reserve are inferior to flow-derived coronary flow reserve as diagnostic and risk stratification tools.

Background: Pressure-derived coronary flow reserve (CFR) and pressure-bounded CFR (CFR) enable simple estimation of CFR from routine pressure measurements, but have been inadequately validated. We sought to compare CFR and CFR against flow-derived CFR (CFR) in terms of diagnostic accuracy, as well as regarding their comparative prognostic relevance.

Methods: We evaluated 453 intermediate coronary lesions with intracoronary pressure and flow measurements.

Fractional Flow Reserve/Instantaneous Wave-Free Ratio Discordance in Angiographically Intermediate Coronary Stenoses: An Analysis Using Doppler-Derived Coronary Flow Measurements.

Objectives: The study sought to determine the coronary flow characteristics of angiographically intermediate stenoses classified as discordant by fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR).

Background: Discordance between FFR and iFR occurs in up to 20% of cases. No comparisons have been reported between the coronary flow characteristics of FFR/iFR discordant and angiographically unobstructed vessels.

Long-term outcomes of a Caucasian cohort presenting with acute coronary syndrome and/or out-of-hospital cardiac arrest caused by coronary spasm.

Background: Coronary artery spasm may be the underlying mechanism in up to 10% of cases of acute coronary syndrome (ACS) and sudden cardiac death. Asian individuals exhibit a 3-times greater incidence of spasm than Caucasians; this is likely due to different types of mechanisms. Consequently, solid data is limited about the long-term prognosis in Caucasian patients presenting with ACS and/or out-of-hospital cardiac arrest (OHCA) caused by coronary spasm.

Microvascular dysfunction following ST-elevation myocardial infarction and its recovery over time.

Aims: It is unclear whether microvascular dysfunction following ST-elevation myocardial infarction (STEMI) is prognostic for long-term left ventricular function (LVF), and whether recovery of the microvasculature status is associated with LVF improvement. The aim of this study was to assess whether microvascular dysfunction in the infarct-related artery (IRA), as assessed by coronary flow reserve (CFR) within one week after PPCI, was associated with LVF at both four months and two years.

Methods And Results: In 62 patients, CFR and hyperaemic microvascular resistance index (HMRI) in the IRA were assessed by intracoronary Doppler flow measurements within one week and at four months.

Invasive minimal Microvascular Resistance Is a New Index to Assess Microcirculatory Function Independent of Obstructive Coronary Artery Disease.

Background: Coronary microcirculatory dysfunction portends a poor cardiovascular outcome. Invasive assessment of microcirculatory dysfunction by coronary flow reserve (CFR) and hyperemic microvascular resistance (HMR) is affected by coronary artery disease (CAD). In this study we propose minimal microvascular resistance (mMR) as a new measure of microcirculatory dysfunction and aim to determine whether mMR is influenced by CAD.

Basal stenosis resistance index derived from simultaneous pressure and flow velocity measurements.

Aims: Vasodilator-free basal stenosis resistance (BSR) equals fractional flow reserve (FFR) accuracy for ischaemia-inducing stenoses. Nonetheless, basal haemodynamic variability may impair BSR accuracy compared with hyperaemic stenosis resistance (HSR). We evaluated the influence of basal haemodynamic variability, as encountered in practice, on BSR accuracy versus HSR when derived from simultaneous pressure and flow velocity measurements, and determined its diagnostic performance for HSR-defined significant stenoses.

Coronary pressure and flow relationships in humans: phasic analysis of normal and pathological vessels and the implications for stenosis assessment: a report from the Iberian-Dutch-English (IDEAL) collaborators.

Background: Our understanding of human coronary physiological behaviour is derived from animal models. We sought to describe physiological behaviour across a large collection of invasive pressure and flow velocity measurements, to provide a better understanding of the relationships between these physiological parameters and to evaluate the rationale for resting stenosis assessment.

Methods And Results: Five hundred and sixty-seven simultaneous intracoronary pressure and flow velocity assessments from 301 patients were analysed for coronary flow velocity, trans-stenotic pressure gradient (TG), and microvascular resistance (MVR).

Combining Baseline Distal-to-Aortic Pressure Ratio and Fractional Flow Reserve in the Assessment of Coronary Stenosis Severity.

Objectives: This study sought to understand the physiological basis of baseline distal-to-aortic pressure ratio (Pd/Pa) and fractional flow reserve (FFR) agreement and discordance, using coronary flow reserve (CFR), stenosis resistance, and microcirculatory resistance measurements, and form there, to investigate the potential value of combining Pd/Pa with FFR in the diagnostic rationale.

Background: Pd/Pa is always available before FFR assessment, and emerging data supports the notion that baseline indices can determine the ischemic potential of coronary stenosis in selected subsets.

Methods: A total of 467 stenosed vessels from 363 patients were investigated with pressure and flow sensors during baseline and hyperemia: 168 vessels (135 patients) with thermodilution-derived flow, and 299 vessels (228 patients) with Doppler-derived flow.

Diagnostic and Prognostic Implications of Coronary Flow Capacity: A Comprehensive Cross-Modality Physiological Concept in Ischemic Heart Disease.

Objectives: The purpose of this study is to evaluate whether coronary flow capacity (CFC) improves discrimination of patients at risk for major adverse cardiac events (MACE) compared with coronary flow reserve (CFR) alone, and to study the diagnostic and prognostic implications of CFC in relation to contemporary diagnostic tests for ischemic heart disease (IHD), including fractional flow reserve (FFR).

Background: Although IHD results from a combination of focal obstructive, diffuse, and microcirculatory involvement of the coronary circulation, its diagnosis remains focused on focal obstructive causes. CFC comprehensively documents flow impairment in IHD, regardless of its origin, by interpreting CFR in relation to maximal flow (hyperemic average peak flow velocity [hAPV]), and overcomes the limitations of using CFR alone.

Change in coronary blood flow after percutaneous coronary intervention in relation to baseline lesion physiology: results of the JUSTIFY-PCI study.

Background: Percutaneous coronary intervention (PCI) aims to increase coronary blood flow by relieving epicardial obstruction. However, no study has objectively confirmed this and assessed changes in flow over different phases of the cardiac cycle. We quantified the change in resting and hyperemic flow velocity after PCI in stenoses defined physiologically by fractional flow reserve and other parameters.

Dynamic preload indicators decrease when the abdomen is opened.

Background: Optimizing cardiac stroke volume during major surgery is of interest to many as a therapeutic target to decrease the incidence of postoperative complications. Because dynamic preload indicators are strongly correlated with stroke volume, it is suggested that these indices can be used for goal directed fluid therapy. However, threshold values of these indicators depend on many factors that are influenced by surgery, including opening of the abdomen.

Primary PCI: time to change focus from epicardial reperfusion towards protection of the microvasculature.

Myocardial tissue perfusion remains compromised in 30-40% of patients with ST-segment elevation myocardial infarction (STEMI) despite restored epicardial patency after primary percutaneous coronary intervention (pPCI). This phenomenon is attributed to microvascular dysfunction secondary to numerous pathophysiological mechanisms, including distal embolisation of plaque and thrombus material. Its association with larger post-infarction myocardial necrosis, impaired left ventricular recovery, and worse clinical outcome illustrates the pertinence of a comprehensive armamentarium for the diagnosis, protection and treatment of microvascular dysfunction in STEMI patients.

Head-to-head comparison of basal stenosis resistance index, instantaneous wave-free ratio, and fractional flow reserve: diagnostic accuracy for stenosis-specific myocardial ischaemia.

Aims: We sought to compare the diagnostic accuracy of basal stenosis resistance index (BSR), instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) for stenosis-specific myocardial ischaemia identified by means of a combined reference standard of myocardial perfusion scintigraphy and the hyperaemic stenosis resistance index.

Methods And Results: BSR and FFR were determined for 299 coronary stenoses, iFR was determined for 85 coronary stenoses (iFR cohort). The discriminative value for stenosis-specific myocardial ischaemia was compared by means of the area under the receiver operating characteristic (ROC) curves (AUC).

Baseline instantaneous wave-free ratio as a pressure-only estimation of underlying coronary flow reserve: results of the JUSTIFY-CFR Study (Joined Coronary Pressure and Flow Analysis to Determine Diagnostic Characteristics of Basal and Hyperemic Indices of Functional Lesion Severity-Coronary Flow Reserve).

Background: Coronary flow reserve has extensive validation as a prognostic marker in coronary disease. Although pressure-only fractional flow reserve (FFR) improves outcomes compared with angiography when guiding percutaneous coronary intervention, it disagrees with coronary flow reserve classification 30% of the time. We evaluated whether baseline instantaneous wave-free ratio (iFR) could provide an improved pressure-only estimation of underlying coronary flow reserve.