Repeatability of fractional flow reserve despite variations in systemic and coronary hemodynamics

Objectives This study classified and quantified the variation in fractional flow reserve (FFR) due to fluctuations in systemic and coronary hemodynamics during intravenous adenosine infusion. Background Although FFR has become a key invasive tool to guide treatment, questions remain regarding its repeatability and stability during intravenous adenosine infusion because of systemic effects that can alter driving pressure and heart rate. Methods We reanalyzed data from the VERIFY (VERification of Instantaneous Wave-Free Ratio and Fractional Flow Reserve for the Assessment of Coronary Artery Stenosis Severity in EverydaY Practice) study, which enrolled consecutive patients who were infused with intravenous adenosine at 140 μg/kg/min and measured FFR twice. Raw phasic pressure tracings from the aorta (Pa) and distal coronary artery (Pd) were transformed into moving averages of Pd/Pa. Visual analysis grouped Pd/Pa curves into patterns of similar response. Quantitative analysis of the Pd/Pa curves identified the “smart minimum” FFR using a novel algorithm, which was compared with human core laboratory analysis. Results A total of 190 complete pairs came from 206 patients after exclusions. Visual analysis revealed 3 Pd/Pa patterns: “classic” (sigmoid) in 57%, “humped” (sigmoid with superimposed bumps of varying height) in 39%, and “unusual” (no pattern) in 4%. The Pd/Pa pattern repeated itself in 67% of patient pairs. Despite variability of Pd/Pa during the hyperemic period, the “smart minimum” FFR demonstrated excellent repeatability (bias −0.001, SD 0.018, paired p = 0.93, r2 = 98.2%, coefficient of variation = 2.5%). Our algorithm produced FFR values not significantly different from human core laboratory analysis (paired p = 0.43 vs. VERIFY; p = 0.34 vs. RESOLVE). Conclusions Intravenous adenosine produced 3 general patterns of Pd/Pa response, with associated variability in aortic and coronary pressure and heart rate during the hyperemic period. Nevertheless, FFR – when chosen appropriately – proved to be a highly reproducible value. Therefore, operators can confidently select the “smart minimum” FFR for patient care. Our results suggest that this selection process can be automated, yet comparable to human core laboratory analysis

An investigation into the attitudes of specialist sports retailers towards sponsorship of local sport

A summary of the field of sponsorship in general and significant prior research is undertaken in order to reveal areas relevant to the specialist sports retailer's involvement in local sports sponsorship. Subsequently, a model is developed of retailer attitudes towards local sports sponsorship through application of the results of a survey of the sports retail trade. Results are statistically tested in a series of hypotheses revealing such factors as : the beneficial effects of sponsorship on the business; the perceived 'ideal' and 'practical' attributes of sponsorship; the constraints on sponsorship activity, such as finance and time; the effects on sponsorship activity of a lack of active involvement in local sports by the sports retailer; the influence of business size on retailer attitudes towards sponsorship; and the considered future support for local sponsorship by the sports retail trade as a whole. The model of retailer attitudes is combined with the findings from a small survey of local sports club attitudes towards business sponsorship in order to create a model of the 'circular exchange process of sponsorship', based on theories outlined by Kotler, Levy and Bagozzi in their studies of marketing transactions and transfers in general. Thus, sponsorship is aligned to the marketing of a saleable commodity, involving sponsor, sponsoree, and other interested parties in the exchange of a series of needs and wants. The 'marketer' is perceived as the sponsor and/or sponsoree, and the importance of giving consideration to the 'coincidence of wants' of all parties involved in a sponsorship programme emphasised

Fractional flow reserve in unstable angina and non-ST-segment elevation myocardial infarction experience from the FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) study

The use of fractional flow reserve (FFR) to guide percutaneous coronary intervention (PCI) is well established in stable angina (SA) but has not been prospectively researched in unstable angina (UA) or non–ST-segment elevation myocardial infarction (NSTEMI). The FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) study compared angiography-guided PCI with FFR-guided PCI in patients with multivessel disease and included patients with SA and UA or NSTEMI. At 2 years, the benefit of using FFR to guide PCI does not differ between patients with UA or NSTEMI, compared with patients with SA

Epicardial stenosis severity does not affect minimal microcirculatory resistance

BACKGROUND: Whether minimal microvascular resistance of the myocardium is affected by the presence of an epicardial stenosis is controversial. Recently, an index of microcirculatory resistance (IMR) was developed that is based on combined measurements of distal coronary pressure and thermodilution-derived mean transit time. In normal coronary arteries, IMR orrelates well with true microvascular resistance. However, to be applicable in the case of an epicardial stenosis, IMR should account for collateral flow. We investigated the feasibility of determining IMR in humans and tested the hypothesis that microvascular resistance is independent of epicardial stenosis. METHODS AND RESULTS: Thirty patients scheduled for percutaneous coronary intervention were studied. The stenosis was stented with a pressure guidewire, and coronary wedge pressure (P(w) ) was measured during balloon occlusion. After successful stenting, a short compliant balloon with a diameter 1.0 mm smaller than the stent was placed in the stented segment and inflated with increasing pressures, creating a 10%, 50%, and 75% area stenosis. At each of the 3 degrees of stenosis, fractional flow reserve (FFR) and IMR were measured at steady-state maximum hyperemia induced by intravenous adenosine. A total of 90 measurements were performed in 30 patients. When uncorrected for P(w), an apparent increase in microvascular resistance was observed with increasing stenosis severity (IMR=24, 27, and 37 U for the 3 different degrees of stenosis;

The impact of downstream coronary stenoses on fractional flow reserve assessment of intermediate left main disease

Objectives The aim of this study was to assess the validity of measuring fractional flow reserve (FFR) of the left main (LM) coronary artery in the setting of concomitant left anterior descending (LAD) or left circumflex (LCX) stenoses. Background The theoretical impact of a stenosis in the LAD on the FFR assessment of intermediate LM disease with the pressure wire in an unobstructed LCX is currently unknown. Methods A previously validated in vitro model of the coronary circulation was used to create a fixed intermediate stenosis of the LM and a variable downstream LAD or LCX stenosis. The true LM FFR (FFRLM true), with no concomitant downstream disease, was compared to the apparent LM FFR (FFRLM apparent), with concomitant downstream disease measured with different degrees of LAD or LCX disease. Additionally, an equation based on a resistors model was derived to predict the effect of downstream stenosis on LM FFR (FFRLM predicted)

Epicardial stenosis severity does not affect minimal microcirculatory resistance

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Response to letter regarding article, "prognostic value of the index of microcirculatory resistance measured after primary percutaneous coronary intervention"

10.1161/CIRCULATIONAHA.113.007271Circulation1297e342-CIRC