Coronary Pressure Wire Research Articles

Diagnostic accuracy of automatic quantitative flow ratio for hemodynamic assessment of coronary artery stenosis: prospective observational study

Abstract Background Quantitative flow ratio (QFR) is a method for evaluating fractional flow reserve (FFR) without the use of an invasive coronary pressure wire or pharmacological hyperemic agent. Automatic QFR (auto QFR) is a recently developed, simpler method of calculating QFR that uses a patient-specific TIMI (Thrombolysis in Myocardial Infarction) frame count, but with automatically specified start and end frames. Although the previous studies demonstrated that contrast QFR is more accurate than fixed QFR, there is no evidence for auto QFR. Purpose The aim of this study was to evaluate the diagnostic performance of auto QFR, fixed QFR, and contrast QFR for the diagnosis of hemodynamically significant coronary stenosis defined by FFR ≤0.80. Methods This prospective, multicentre trial enrolled patients suspected with coronary artery disease undergoing diagnostic coronary angiography with an indication for to perform invasive FFR. QFR was calculated at a blinded core laboratory. The primary endpoint was the diagnostic accuracy of auto QFR, fixed QFR, and contrast QFR to determine hemodynamically significant coronary stenosis using invasive FFR (≤0.80) as a reference standard. Results A total of 325 vessels from 274 patients were analysed. Mean FFR was 0.82±0.09, mean auto QFR was 0.80±0.12, and mean contrast QFR was 0.82±0.11, respectively. The overall diagnostic accuracy for identifying an FFR of ≤0.80 was highest by contrast QFR (81.5%), followed by fixed QFR (79.1%), and auto QFR (77.5%). The AUC was higher for contrast QFR (AUC 0.885; 95% CI: 0.845-0.925) than fixed QFR (AUC 0.856; 95% CI: 0.812-0.900) or auto QFR (AUC 0.854; 95% CI: 0.806-0.901), but did not differ significantly between fixed QFR and auto QFR (Figure). Conclusions There was no significant difference in AUC between fixed and auto QFR, but the accuracy of contrast QFR was significantly higher compared to both QFRs. Auto QFR has the advantage of faster computation time while using patient-specific coronary flow, but accuracy still needs to be improved.

Safety and Feasibility Using a Fluid-Filled Wire to Avoid Hydrostatic Errors in Physiological Intracoronary Measurements.

Using a fluid-filled wire with a pressure sensor outside the patient compared to a conventional pressure wire may avoid the systematic error introduced by the hydrostatic pressure within the coronary circulation. To assess the safety and effectiveness of the novel fluid-filled wire, Wirecath (Cavis Technologies, Uppsala, Sweden), as well as its ability to avoid the hydrostatic pressure error. The Wirecath pressure wire was used in 45 eligible patients who underwent invasive coronary angiography and had a clinical indication for invasive coronary pressure measurement at Sahlgrenska University Hospital, Gothenburg, Sweden. In 29 patients, a simultaneous measurement was performed with a conventional coronary pressure wire (PressureWire X, Abbott Medical, Plymouth, MN, USA), and in 19 patients, the vertical height difference between the tip of the guide catheter and the wire measure point was measured in a 90-degree lateral angiographic projection. No adverse events caused by the pressure wires were reported. The mean Pd/Pa and mean FFR using the fluid-filled wire and the sensor-tipped wire differed significantly; however, after correcting for the hydrostatic effect, the sensor-tipped wire pressure correlated well with the fluid-filled wire pressure (R = 0.74 vs. R = 0.89 at rest and R = 0.89 vs. R = 0.98 at hyperemia). Hydrostatic errors in physiologic measurements can be avoided by using the fluid-filled Wirecath wire, which was safe to use in the present study. This trial is registered with NCT04776577 and NCT04802681.

The imPAct of Trimetazidine on MicrOcirculation after Stenting for stable coronary artery disease (PATMOS study).

Myocardial ischemia is caused by epicardial coronary artery stenosis or atherosclerotic disease affecting microcirculation. Trimetazidine (TMZ), promotes glucose oxidation which optimizes cellular energy processes in ischemic conditions. Small studies demonstrated protective effects of TMZ in terms of reducing myocardial injury after percutaneous coronary intervention (PCI), its effect on microcirculation using contemporary investigative methods has not been studied. The aim of the study was to examine effects of trimetazidine, given before elective PCI, on microcirculation using invasively measured index of microcirculatory resistance (IMR). This was prospective, single blinded, randomized study performed in a single university hospital. It included consecutive patients with an indication for PCI of a single, de novo, native coronary artery lesion. Patients were randomly assigned to receive either TMZ plus standard therapy (TMZ group) or just standard therapy. Coronary physiology indices fractional flow reserve (FFR), coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) were measured before and after PCI using coronary pressure wire. We randomized 71 patients with similar clinical characteristics and risk profile, previous medications and coronary angiograms. Patientshad similar values of Pd/Pa, FFR and CFR prior to PCI procedure. After PCI, FFR values were higher in TMZ group, while IMR values were lower in this group respectively (FFR TMZ + 0.89 ± 0.05 vs. TMZ - 0.85 ± 0.06, p = 0.007; CFR TMZ + 2.1 ± 0.8 vs. TMZ- 2.3 ± 1.3, p = 0.469; IMR TMZ + 18 ± 9 vs. TMZ- 24 ± 12, p = 0.028). In two-way repeated measures ANOVA PCI was associated with change in FFR values (TMZ p = 0.050; PCI p < 0.001; p for interaction 0.577) and TMZ with change in IMR values (TMZ p = 0.034, PCI p = 0.129, p for interaction 0.344). Adding trimetazidine on top of medical treatment prior to elective PCI reduces microvascular dysfunction by lowering postprocedural IMR values when compared to standard therapy alone.

First Experience of Measuring Index of Microcirculatory Resistance at Auckland City Hospital

Patients with angina and non-obstructive coronary artery disease (NOCAD) present an important diagnostic and management challenge. Measurement of the index of microcirculatory resistance (IMR) with a coronary pressure wire at the time of invasive coronary angiography can help distinguish between microvascular angina and non-cardiac chest pain. A retrospective audit was undertaken of consecutive patients with NOCAD and measurement of microvascular indices from the Northern region between March 2020 and January 2023 at Auckland City Hospital (ACH). Coronary flow reserve, IMR, and fractional flow reserve were measured, as shown in the Table. Sixty-two patients had IMR measured and seven were excluded as they were out of area; 75% were male and the mean age was 65 (SD 8.6) years. An elevated IMR was found in 24 (43%); 47% had history of smoking, 24% previous myocardial infarction, 7% previous stroke, and 51% diabetes; 52% presented with stable angina, 24% with unstable angina, and 22% with non-ST elevation myocardial infarction; and 70% were on aspirin, 44% on beta blockers, 18% on calcium channel blockers, 31% nitrates, 38% statins, and 2% nicorandil.TableMedianInterquartile rangeHeart rate (per minute)75.9(64.6, 87.2)Coronary flow reserve (CFR)3.51(2.18, 4.79)Index of microcirculatory resistance (IMR)22.8(14.8, 39.8)Fractional flow reserve (FFR)0.85(0.81, 0.90)Gensini score7.5(2.6, 18.6) Open table in a new tab This study describes initial experience in measuring IMR amongst patients with NOCAD at ACH. This cohort had a low burden of coronary disease. IMR provides useful diagnostic information that informs management.

Four of Five Patients With Chest Pain and Non-Obstructive Coronary Artery Disease who had a Microvascular Assessment had Microvascular Angina

Patients with chest pain and non-obstructive coronary artery disease (NOCAD) may have microvascular disease. Measurement of the index of microcirculatory resistance (IMR) with a coronary pressure wire at the time of invasive coronary angiography identifies those with microvascular disease. This helps to correctly diagnose these patients and tailor their therapeutic strategy. A retrospective audit was undertaken of consecutive patients with NOCAD and measurement of microvascular indices from the Northern region between March 2020 and January 2023 at Auckland City Hospital. Coronary flow reserve, IMR, and fractional flow reserve were measured. Fifty-six participants were included. Seven were excluded as they resided outside the Northern region. Forty-one (75%) were male with mean age of 65 (SD 8.6) years. A total of 47% had a history of smoking, 24% previous myocardial infarction, 7% previous stroke, 51% diabetes; 52% presented with stable angina, 24% with unstable angina and 22% with non-ST elevation myocardial infarction (NSTEMI); 70% were on aspirin, 44% on beta blockers, 18% on calcium channel blockers, 31% nitrates, 38% statins, and 2% nicorandil. Normal IMR (<25) was seen in 24% of patients with an initial diagnosis of stable angina, 15% with unstable angina, and 17% with NSTEMI. Amongst those with chest pain and NOCAD, who had a microvascular assessment, four of five had an elevated IMR, suggesting significant microvascular disease. The remaining patients were reassured that their chest pain was not due to coronary disease. These data reinforce the diagnostic value of IMR in this patient cohort.

The Impact of Trimethylamine N-Oxide and Coronary Microcirculatory Dysfunction on Outcomes following ST-Elevation Myocardial Infarction

Persistent coronary microcirculatory dysfunction (CMD) and elevated trimethylamine N-oxide (TMAO) levels after ST-elevation myocardial infarction (STEMI) may drive negative structural and electrical cardiac remodeling, resulting in new-onset atrial fibrillation (AF) and a decrease in left ventricular ejection fraction (LVEF). TMAO and CMD are investigated as potential predictors of new-onset AF and left ventricular remodeling following STEMI. This prospective study included STEMI patients who had primary percutaneous coronary intervention (PCI) followed by staged PCI three months later. Cardiac ultrasound images were obtained at baseline and after 12 months to assess LVEF. Coronary flow reserve (CFR), and index of microvascular resistance (IMR) were assessed using the coronary pressure wire during the staged PCI. Microcirculatory dysfunction was defined as having an IMR value ≥25 U and CFR value <2.5 U. A total of 200 patients were included in the study. Patients were categorized according to whether or not they had CMD. Neither group differed from the other with regards to known risk factors. Despite making up only 40.5% of the study population, females represented 67.4% of the CMD group p < 0.001. Similarly, CMD patients had a much higher prevalence of diabetes than those without CMD (45.7% vs. 18.2%; p < 0.001). At the one-year follow-up, the LVEF in the CMD group had decreased to significantly lower levels than those in the non-CMD group (40% vs. 50%; p < 0.001), whereas it had been higher in the CMD group at baseline (45% vs. 40%; p = 0.019). Similarly, during the follow-up, the CMD group had a greater incidence of AF (32.6% vs. 4.5%; p < 0.001). In the adjusted multivariable analysis, the IMR and TMAO were associated with increased odds of AF development (OR: 1.066, 95% CI: 1.018-1.117, p = 0.007), and (OR: 1.290, 95% CI: 1.002-1.660, p = 0.048), respectively. Similarly, elevated levels of IMR and TMAO were linked with decreased odds of LVEF improvement, while higher CFR values are related to a greater likelihood of LVEF improvement. CMD and elevated TMAO levels were highly prevalent three months after STEMI. Patients with CMD had an increased incidence of AF and a lower LVEF 12 months after STEMI.

TCT-283 Impact of Plaque Morphology on Invasive Coronary Physiology and Pressure Wire Discordance—Preliminary Results From the iEquate Trial

TCT-283 Impact of Plaque Morphology on Invasive Coronary Physiology and Pressure Wire Discordance—Preliminary Results From the iEquate Trial

Real time reduced order model for angiography fractional flow reserve

Background and ObjectivesFractional flow reserve (FFR) is the gold standard for quantification of coronary stenosis and pressure wire is the gold standard for measuring FFR. Recently, computational fluid dynamics (CFD) methods have been used to compute FFR less invasively using images obtained from coronary angiography. This approach is, however, computationally intensive and solutions to reduce computation time are clearly required. MethodsWe hypothesized that FFR can be calculated instantly using a reduced order model (ROM) derived using response surface method (RSM) for simulation modeling in lieu of the computationally intensive CFD. Specifically, eleven physiological and anatomical factors known to affect FFR were selected as input variables, and Plackett–Burman analysis was performed in conjunction with CFD on model arteries to identify set of variables affecting FFR the most. Based on the Box–Behnken design, a mathematical model was developed to compute FFR using the retained set of variables. ResultsThe model fidelity was tested on a cohort of 90 patients (100 coronary arteries) with known pressure-wire FFR. FFR derived from this ROM had a strong correlation with pressure-wire FFR with sensitivity of 89.4%, specificity of 100% and area under curve of 0.947 (p < 0.05). ConclusionsThe ROM method can be used to reliably calculate FFR in patients with coronary stenosis and able to replace time-consuming CFD-based FFR estimation and provide instead a real-time calculation method.

Comparison of Resting Full-Cycle Ratio and Fractional Flow Reserve in a German Real-World Cohort.

Objective: The aim of this study was to evaluate non-hyperemic resting pressure ratios (NHPRs), especially the novel “resting full-cycle ratio” (RFR; lowest pressure distal to the stenosis/aortic pressure during the entire cardiac cycle), compared to the gold standard fractional flow reserve (FFR) in a “real-world” setting.Methods: The study included patients undergoing coronary pressure wire studies at one German University Hospital. No patients were excluded based on any baseline or procedural characteristics, except for insufficient quality of traces. The diagnostic performance of four NHPRs vs. FFR ≤ 0.80 was tested. Morphological characteristics of stenoses were analyzed by quantitative coronary angiography.Results: 617 patients with 712 coronary lesions were included. RFR showed a significant correlation with FFR (r = 0.766, p < 0.01). Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of RFR were 78% (95% confidence interval = 75; 81), 72% (65; 78), 81% (77; 84), 63% (57; 69), and 86% (83; 89). Relevant predictors for discordance of RFR ≤ 0.89/FFR > 0.8 were LAD lesions, peripheral artery disease, age, female sex and non-focal stenoses. Predictors for discordance of RFR > 0.89/FFR ≤ 0.8 included non-LCX lesions, percent diameter stenosis and previous percutaneous coronary intervention in the target vessel. RFR and all other NHPRs were highly correlated with each other.Conclusion: All NHPRs have a similar correlation with the gold standard FFR and may facilitate the acceptance and implementation of physiological assessments of lesion severity. However, we found ~20% discordant results between NHPRs and FFR in our “all-comers” German cohort.

Performance of quantitative flow ratio in patients with aortic stenosis undergoing transcatheter aortic valve implantation.

This study aims to evaluate the diagnostic performance of quantitative flow ratio (QFR) pre transcatheter aortic valve implantation (TAVI) in patients with aortic valve stenosis (AS) and coronary artery disease (CAD). Post-TAVI fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) was used as reference. CAD is prevalent in patients with AS, but the hemodynamics of AS confounds evaluation using pressure wire-based assessments. QFR might be less sensitive to the presence of AS thereby allowing for CAD evaluation before aortic valve replacement. Further, QFR does not require the use of pressure wire and therefore has the potential for reducing costs and complications related to insertion of a coronary pressure wire. The diagnostic performance of QFR in coronary angiograms from 28 patients undergoing TAVI was evaluated. In all patients, both FFR and iFR were measured pre- and immediately post-TAVI while QFR was measured pre-TAVI. Using post-TAVI FFR and iFR as reference the diagnostic accuracy of pre-TAVI QFR were 83% (95%CI; 68-97) and 52% (95%CI; 30-74) p=.008, respectively. Pre-TAVI QFR showed a good diagnostic performance using post-TAVI FFR as reference. QFR could become a wire-free, safe, and quick way of evaluating CAD in patients with severe AS undergoing TAVI.

Coronary Physiology Derived from Invasive Angiography: Will it be a Game Changer?

There is a large body of evidence suggesting that having knowledge of the presence and extent of coronary atheroma and whether it is causing downstream myocardial ischaemia facilitates optimal diagnosis and management for patients presenting with chest pain. Despite this, the use of coronary pressure wire in routine practice is surprisingly low and routine assessment of all diseased vessels before making a bespoke management plan is rare. The advent of angiogram-derived models of physiology could change diagnostic practice completely. By offering routine assessment of the physiology of all the major epicardial coronary vessels, angiogram-derived physiology has the potential to radically modify current practice by facilitating more accurate patient-level, vessel-level, and even lesion-level decision-making. In this article, the authors review the current state of angiogram-derived physiology and speculate on its potential impact on clinical practice.

P854Physiological patterns of coronary artery disease

Abstract Background Randomised controlled trials have confirmed the clinical benefit of invasive functional assessment to guide clinical decision making about myocardial revascularisation in patients with stable coronary artery disease. Treatment decision is based on one FFR value which provides a vessel-level metric as a surrogate of myocardial ischaemia. Also, the distribution of epicardial conductance can be evaluated using an FFR pullback manoeuvre. Purpose The objective of the present study is to characterise the physiological patterns of CAD using motorised coronary pressure pullbacks during continuous hyperaemia in patients with stable coronary artery disease. Methods Prospective, multicentre study of patients undergoing clinically-indicated coronary angiography. A pullback device, adapted to grip the coronary pressure wire, was set at a speed of 1 mm/sec. The pattern of CAD was adjudicated by visual inspection of the FFR pullback curves as focal, diffuse, or a combination of both mechanisms. Also, a quantitative classification of the physiological pattern of CAD was performed based on (1) the functional contribution of the epicardial lesion in relation to the total vessel FFR (Δlesion FFR/Δvessel FFR) and (2) the length (mm) of epicardial coronary segments with FFR drops in relation to the total vessel length. The combination of these two ratios, namely, lesion-related pressure drops (%FFR-lesion), and the extent of functional disease, resulted in the functional outcomes index (FOI), a metric that represents the pattern of CAD (i.e. focality or diffuseness) based on coronary physiology. Agreement on CAD patterns and between observers was assessed using Fleiss' Kappa. Analysis of variance (ANOVA) was used to compared quantitative variables. Correlation between variables was assessed by the Pearson moment coefficient. Results One hundred and fifty-eight vessels were included; 984,813 FFR values were used to generate the FFR pullback curves. Using motorised FFR pullbacks, 34% of the vessel disease patterns (i.e. focal, diffuse or combined) were reclassified compared to conventional angiography. The mean contribution of the angiographic lesions to the distal FFR (%FFR-lesion) was 61.7±25% whereas vessel length with the physiological disease was 59.8±21% of the total vessel length. The mean FOI was 0.61±0.17, and differentiated focal from diffuse CAD in terms of %FFR-lesion (p&lt;0.001) and physiological extent of CAD (p&lt;0.001). Conclusion Coronary angiography was inaccurate to assess the patterns of CAD. The inclusion of the functional component reclassified 34% of the vessel disease patterns (i.e. focal, diffuse or combined). A new metric, the FOI, based on the functional impact of anatomical lesions and the extent of physiological disease, discriminated focal from diffuse CAD. Further clinical trials are required to evaluate the usefulness of FOI for clinical decision making and outcomes.

TCT-783 Feasibility of Using Radial Access and 4Fr Catheters for Coronary Pressure Wire Measurements

Radial artery access for coronary angiography has been associated with lower vascular complications, major bleeding events, ischemic events, and all-cause mortality compared with femoral access. The radial approach has become the preferred approach for both diagnostic coronary angiography and

Accuracy of Fractional Flow Reserve Derived From Coronary Angiography.

Measuring fractional flow reserve (FFR) with a pressure wire remains underutilized because of the invasiveness of guide wire placement or the need for a hyperemic stimulus. FFR derived from routine coronary angiography (FFRangio) eliminates both of these requirements and displays FFR values of the entire coronary tree. The FFRangio Accuracy versus Standard FFR (FAST-FFR) study is a prospective, multicenter, international trial with the primary goal of determining the accuracy of FFRangio. Coronary angiography was performed in a routine fashion in patients with suspected coronary artery disease. FFR was measured in vessels with coronary lesions of varying severity using a coronary pressure wire and hyperemic stimulus. Based on angiograms of the respective arteries acquired in ≥2 different projections, on-site operators blinded to FFR then calculated FFRangio using proprietary software. Coprimary end points were the sensitivity and specificity of the dichotomously scored FFRangio for predicting pressure wire-derived FFR using a cutoff value of 0.80. The study was powered to meet prespecified performance goals for sensitivity and specificity. Ten centers in the United States, Europe, and Israel enrolled a total of 301 subjects and 319 vessels meeting inclusion/exclusion criteria which were included in the final analysis. The mean FFR was 0.81 and 43% of vessels had an FFR≤0.80. The per-vessel sensitivity and specificity were 94% (95% CI, 88% to 97%) and 91% (86% to 95%), respectively, both of which exceeded the prespecified performance goals. The diagnostic accuracy of FFRangio was 92% overall and remained high when only considering FFR values between 0.75 to 0.85 (87%). FFRangio values correlated well with FFR measurements ( r=0.80, P<0.001) and the Bland-Altman 95% confidence limits were between -0.14 and 0.12. The device success rate for FFRangio was 99%. FFRangio measured from the coronary angiogram alone has a high sensitivity, specificity, and accuracy compared with pressure wire-derived FFR. FFRangio has the promise to substantially increase physiological coronary lesion assessment in the catheterization laboratory, thereby potentially leading to improved patient outcomes. URL: https://www.clinicaltrials.gov . Unique Identifier: NCT03226262.

Sex Differences in Adenosine-Free Coronary Pressure Indexes: A CONTRAST Substudy

ObjectivesThe goal of this study was to investigate sex differences in adenosine-free coronary pressure indexes. BackgroundSeveral adenosine-free coronary pressure wire indexes have been proposed to assess the functional significance of coronary artery lesions; however, there is a theoretical concern that sex differences may affect diagnostic performance because of differences in resting flow and distal myocardial mass. MethodsIn this CONTRAST (Can Contrast Injection Better Approximate FFR Compared to Pure Resting Physiology?) substudy, contrast fractional flow reserve (cFFR), obtained during contrast-induced submaximal hyperemia, the instantaneous wave-free ratio (iFR), and distal/proximal coronary pressure ratio (Pd/Pa) were compared with fractional flow reserve (FFR) in 547 men and 216 women. Using FFR ≤0.8 as a reference, the diagnostic performance of each index was compared. ResultsMen and women had similar diameter stenosis (p = 0.78), but women were less likely to have FFR ≤0.80 than men (42.5% vs. 51.5%, p = 0.04). Sensitivity was similar among cFFR, iFR, and Pd/Pa when comparing women and men, respectively (cFFR, 77.5% vs. 75.3%; p = 0.69; iFR, 84.9% vs. 79.4%; p = 0.30; Pd/Pa, 78.8% vs. 77.3%; p = 0.78). cFFR was more specific than iFR or Pd/Pa regardless of sex (cFFR, 94.3% vs. 95.8%; p = 0.56; iFR, 75.6% vs. 80.1%; p = 0.38; Pd/Pa, 80.6% vs. 78.7%; p = 0.69). By receiver-operating characteristic curve analysis, cFFR provided better diagnostic accuracy than resting indexes irrespective of sex (p ≤ 0.0001). ConclusionsDespite the theoretical concern, the diagnostic sensitivity and specificity of cFFR, iFR, and Pd/Pa did not differ between the sexes. Irrespective of sex, cFFR provides the best diagnostic performance.

Development of a Porcine Model of Coronary Stenosis Using Fully Percutaneous Techniques Suitable For Performing Cardiac Computed Tomography, CT-Perfusion Imaging and Fractional Flow Reserve

The aim of this study was to develop and describe percutaneous coronary angiographic techniques to create a porcine model of acute coronary stenosis with methacrylate plugs that can by assessed using fractional flow reserve (FFR), invasive coronary angiography and coronary computed tomographic (CT) perfusion imaging without introducing artefacts associated with surgical models. Following animal care and institutional approval and using percutaneous coronary catheterisation techniques within an animal laboratory we introduced precision drilled methacrylate plugs into one of the three main coronary arteries of 10 experimental female pigs. Coronary pressure wire measurements were performed across the experimental stenosis for the calculation of FFR. Invasive coronary angiograms were obtained in stenosed arteries. Animals were transported to a dual source CT scanner (Siemens Healthcare, Forcheim, Germany) and CT perfusion imaging was performed. Ten (10) pigs were investigated with seven data sets obtained. Three (3) pigs expired prior to CT imaging secondary to pneumothorax, high grade coronary stenosis with induced cardiac arrhythmia and iatrogenic air embolism. Graded coronary stenosis was produced in six pigs in the LAD (2), LCX (2) and RCA (2) territories and one animal served as a control. Fractional flow reserve ranged from 0.21 to 0.91. Myocardial blood flow derived from dynamic CT perfusion imaging ranged from 3.5 to 136.7ml/100ml of tissue/minute. No artefacts from the deployment of the methacrylate plug, nor the plug itself, were identified. Fully percutaneous preparation of a pig model of acute coronary stenosis is feasible and provides subjects for imaging that are free of surgically induced artefact. This technique is substantially less expensive than surgically induced coronary stenosis and can be performed using standard catheterisation techniques with mobile imaging equipment. The technique is extendable to produce multivessel acute coronary stenosis and can be used for multimodality imaging.

Effects of Impella on Coronary Perfusion in Patients With Critical Coronary Artery Stenosis

Mechanical circulatory support devices are used to maintain hemodynamic stability during high-risk percutaneous coronary interventions. Little is known on the effects of such devices on coronary hemodynamics in patients with significant coronary stenosis. We sought to investigate whether mechanical circulatory support in the form of Impella (Abiomed Inc, Danvers, MA) can improve coronary hemodynamics in the presence of a critical coronary stenosis. We examined coronary perfusion pressures and coronary pressure distal to a critical stenosis using a coronary pressure wire in 11 patients (12 coronary lesions) undergoing high-risk percutaneous coronary interventions with the use of mechanical circulatory support. Systemic, ventricular, and coronary hemodynamics were obtained at both minimum and maximum support levels before high-risk percutaneous coronary interventions. All patients had obstructive lesions with angiographically estimated diameter stenosis between 70% and 99% and distal coronary artery pressure to aortic pressure ratios between 0.44 and 0.88. When compared with minimum support, maximum support resulted in a decrease in the left ventricular end-diastolic pressure (27.3±8.6 versus 21.5±5.2 mm Hg; P=0.002) and increases in the mean systemic blood pressure (77.6±13.5 versus 88.2±12.2 mm Hg; P<0.001) and mean distal coronary pressure (51.8±20.2 versus 60.8±18.1 mm Hg; P<0.001). Effective coronary perfusion pressure (mean aortic pressure-left ventricular end-diastolic pressure) significantly increased with maximum support (49.8±15.7 versus 67.2±13.6 mm Hg; P<0.001). Diastolic perfusion pressure (diastolic blood pressure-left ventricular end-diastolic pressure) also significantly increased with maximum support (32.9±13.4 versus 52.0±11.6 mm Hg; P<0.001). Mechanical circulatory support with Impella can improve distal coronary pressure and coronary perfusion pressures in the presence of critical coronary stenosis.

SEX DIFFERENCES AND ADENOSINE FREE CORONARY PRESSURE INDICES: A CONTRAST SUBSTUDY

Several adenosine-free coronary pressure wire indices have been proposed to assess the functional significance of coronary artery lesions. However, there is a theoretical concern that sex differences may affect diagnostic performance due to differences in resting flow. In the CONTRAST (Can Contrast

Safety and utility of dobutamine and pressure wire use in the hemodynamic assessment of low-flow, low-gradient aortic stenosis with reduced left ventricular ejection fraction.

The ACC/AHA guidelines recommend low-dose dobutamine challenge for hemodynamic assessment of the severity of AS in patients with low flow, low gradient aortic stenosis with reduced ejection fraction (EF) (LFLG-AS; stage D2). Inherent pitfalls of echocardiography could result in inaccurate aortic valve areas (AVA), which have downstream prognostic implications. Data on the safety and efficacy of coronary pressure wire and fluid-filled catheter use for low dose dobutamine infusion is sparse. We retrospectively analyzed 39 consecutive patients with EF<50%, AVA<1cm2 and SVI<35ml/m2 on echocardiography who underwent simultaneous right and left heart catheterization. Hemodynamic assessments were performed at baseline and at every increment in the dobutamine infusion rate (The infusion was continued until maximal dose of dobutamine or a mean AV gradient>40mmHg was attained. The occurrence of sustained ventricular arrhythmias, symptomatic hypotension or intolerable symptoms leading to cessation of infusion was recorded. Transient ischemic attacks (TIAs) or clinically apparent strokes periprocedurally or up to 30days after the procedure were recorded. Dobutamine challenge confirmed true AS in 26 patients (67%) and pseudosevere AS in 34%. No sustained arrhythmias, hypotension or cessation of infusion from intolerable symptoms were observed. No clinical strokes or TIAs were observed up to 30days after procedure in any of these patients. Hemodynamic assessment of AS using a pressure wire with dobutamine challenge is a safe and effective tool in identifying truly severe AS in patients with LFLG-AS with reduced EF.

Impact of Asymmetric Dimethylarginine on Coronary Physiology Early After Heart Transplantation

Cardiac allograft vasculopathy is a major cause of long-term graft failure following heart transplantation. Asymmetric dimethylarginine (ADMA), a marker of endothelial dysfunction, has been mechanistically implicated in the development of cardiac allograft vasculopathy, but its impact on coronary physiology early after transplantation is unknown. Invasive indices of coronary physiology, namely, fractional flow reserve (FFR), the index of microcirculatory resistance, and coronary flow reserve, were measured with a coronary pressure wire in the left anterior descending artery within 8 weeks (baseline) and 1 year after transplant. Plasma levels of ADMA were concurrently assayed using high-performance liquid chromatography. In 46 heart transplant recipients, there was a statistically significant correlation between elevated ADMA levels and lower FFR values at baseline (r = -0.33; p = 0.024); this modest association persisted 1 year after transplant (r = -0.39; p = 0.0085). Patients with a baseline FFR <0.90 (a prognostically validated cutoff) had significantly higher baseline ADMA levels (0.63 ± 0.16 vs 0.54 ± 0.12 µM; p = 0.034). Baseline ADMA (odds ratio 1.80 per 0.1 µM; 95% confidence interval 1.07 to 3.03; p = 0.027) independently predicted a baseline FFR <0.90 after multivariable adjustment. Even after dichotomizing ADMA (≥0.60 µM, provides greatest diagnostic accuracy by receiver operating characteristic curve), this association remained significant (odds ratio 7.52, 95% confidence interval 1.74 to 32.49; p = 0.006). No significant relationship between ADMA and index of microcirculatory resistance or coronary flow reserve was detected. In conclusion, baseline ADMA was a strong independent predictor of FFR <0.90, suggesting that elevated ADMA levels are associated with abnormal epicardial function soon after heart transplantation.