Intravenous Administration Of Adenosine Research Articles

Use of coronary physiology to guide revascularization in clinical practice: results of the F(FR)2 registry

BackgroundDespite the recommendation of coronary physiology to guide revascularization in angiographically intermediate stenoses without established correlation to ischemia, its uptake in clinical practice is slow.AimsThis study aimed to analyze the use of coronary physiology in clinical practice.MethodsBased on a multicenter registry (Fractional Flow Reserve Fax Registry, F(FR)2, ClinicalTrials.gov identifier NCT03055910), clinical use, consequences, and complications of coronary physiology were systematically analyzed.ResultsF(FR)2 enrolled 2,000 patients with 3,378 intracoronary pressure measurements. Most measurements (96.8%) were performed in angiographically intermediate stenoses. Out of 3,238 lesions in which coronary physiology was used to guide revascularization, revascularization was deferred in 2,643 (78.2%) cases.Fractional flow reserve (FFR) was the most common pressure index used (87.6%), with hyperemia induced by an intracoronary bolus of adenosine in 2,556 lesions (86.4%) and intravenous adenosine used for 384 measurements (13.0%). The route of adenosine administration did not influence FFR results (change-in-estimate -3.1% for regression model predicting FFR from diameter stenosis). Agreement with the subsequent revascularization decision was 93.4% for intravenous and 95.0% for intracoronary adenosine (p = 0.261).Coronary artery occlusion caused by the pressure wire was reported in two cases (0.1%) and dissection in three cases (0.2%), which was fatal once (0.1%).ConclusionsIn clinical practice, intracoronary pressure measurements are mostly used to guide revascularization decisions in angiographically intermediate stenoses. Intracoronary and intravenous administration of adenosine seem equally suited. While the rate of serious complications of wire-based intracoronary pressure measurements in clinical practice seems to be low, it is not negligible.Graphical abstract

Impact of Mitral Regurgitation on the Hyperemic Induction by Intravenous Administration of Adenosine

Impact of Mitral Regurgitation on the Hyperemic Induction by Intravenous Administration of Adenosine

Safety of Adenosine for the Treatment of Supraventricular Tachycardia in Hospitalized Patients with COVID-19 Pneumonia.

Coronavirus disease 2019 (COVID-19) is associated with pulmonary involvement and cardiac arrhythmias, including supraventricular tachycardia (SVT). Adenosine is commonly used to treat SVT and is generally safe, but is rarely associated with bronchospasm. There are no data regarding the safety of adenosine use in patients with COVID-19 pneumonia and physicians may hesitate to use it in such patients. We surveyed resident physicians and cardiology attendings regarding their level of comfort in administering adenosine to hospitalized COVID-19 patients. We compared a study group of 42 COVID-19 hospitalized patients who received adenosine for SVT to a matched (for age, sex, and co-morbidities) control group of 42 non-COVID-19 hospitalized patients during the same period, all of whom received IV adenosine for SVT. Escalation of care following intravenous adenosine administration was defined as increased/new pressor requirement, need for higher O2 flow rates, need for endotracheal intubation, new nebulizer therapy, or transfer to intensive care unit within 2 h of adenosine administration. Survey results showed that 82% (59/72) of residents and 62% (16/26) of cardiologists expressed hesitation/significant concerns regarding administering adenosine in hospitalized COVID-19 patients. Adenosine use was associated with escalation of care in 47.6% (20/42) COVID-19 as compared to 50% (21/42) non-COVID-19 patients (odds ratio 0.95, 95% CI 0.45-2.01, p = NS). Escalation of care was more likely in patients who were on higher FiO2, on prior nebulizer therapy, required supplemental oxygen, or were already on a ventilator. In conclusion, we identified significant hesitation among physicians regarding the use of adenosine for SVT in hospitalized COVID-19 patients. In this study, there was no evidence of increased harm from administering adenosine to patients with SVT and COVID-19. This finding needs to be confirmed in larger studies. Based on the current evidence, adenosine for treatment of SVT in this setting should not be avoided. Key Points: Question: Given the known bronchospastic effects of adenosine, is the use of adenosine safe for treatment of supraventricular tachycardia in hospitalized patients with COVID-19? Findings: A survey of residents and cardiology attending identified that a majority expressed some level of apprehension in using adenosine for SVT in COVID-19 patients. In our matched cohort study, we found adenosine use to be comparably safe in COVID-19 and non-COVID-19 hospitalized patients. Meaning: Based on current evidence, adenosine for treatment of SVT in this setting should not be avoided.

Early dose of Adenosine, postRadiofrequency abLation of accessory pathwaYin determining acute procedural success (EARLY study).

Post ablation of the accessory pathway (AP), the patient is observed in the catheterization laboratory for a variable period for resumption of pathway conduction. Aim of the study was to determine whether the administration of intravenous adenosine at 10 min after ablation of APwould have the same diagnostic accuracy as waiting for 30 min in predicting the resumption of AP conduction. This was a prospective interventional study conducted in two centers. Post ablation of the AP, intravenous adenosine was administered at 10 min to look for dormant pathway conduction. The response was recorded as positive (presence of pathway conduction), negative (absence), or indeterminate (not able to demonstrate AV and VA block and inability to ascertain AP conduction). The study included 110 procedures performed in 109 patients. Adenosine administration at 10 min showed positive result in 3 cases (2.7%), negative result in 99 cases (90%) and indeterminate result in 8 cases (7.3%). Reconnection of accessory pathway at 30 min postablation was seen in 8 cases (7.3%). Of these 8 cases, 10 minadenosine administration showed positive test in 3 patients and negative test in 5 patients. Adenosine test at 10 min has a sensitivity, specificity, positive predictive value, and negative predictive value of 37.5%, 100%, 100%, and 94.9% in identifying the recurrence of accessory pathway conduction at 30 min, respectively. Absence of pathway conduction on administration of adenosine 10 min postablation does not help predict the absence of resumption of conduction thereafter.

The effect of iron deficiency and goiter on the adaptation process of iatrogenic cerebral vasodilation and cardiac parameters

Aim: Adenosine is a pharmacological stress agent used in many nuclear medicine clinics. It causes different and widespread effects in different tissues. It causes widespread inhibition and cerebral vasodilation through A1 and A2a receptors in the central nervous system. We evaluated the duration of side effects in patients with iron deficiency and euthyroid goiter. Materials and Methods: Our study included 183 patients with atypical chest pain who underwent myocardial perfusion scintigraphy to investigate the presence of coronary artery disease. Adenosine infusion was administered intravenously at a rate of 140 µg/kg/min for 6 minutes. Complaints that occurred during intravenous administration of adenosine were questioned. The presence of at least three of the most common complaints of flushing, headache, nausea, and feeling of ill feeling was considered to have prominent complaints. If these complaints continued for at least 30 minutes, the presence of prolonged prominent complaints was accepted. Patients who developed prolonged complaints were categorized as group 1 and patients without prolonged complaints as group 2. Results: The number of patients diagnosed with euthyroid goiter was significantly higher in Group 1 (p<0.005). Additionally, thyroid size was significantly larger in patients in Group 1 compared to those in Group 2, with respective medians (minimum-maximum) of 20 (11-18 ml) and 15 (11-28 ml) (p<0.005). In group 1, 44 (86.3%) patients had iron deficiency, while in group 2 37 (28%) patients had iron deficiency (p<0.005). The free variables determining the development of prolonged prominent complaints in patients who received adenosine infusion were found to be goiter size (Odds: 1.437, confidence interval: 1.264-1.633; p<0.005) and presence of iron deficiency (Odds: 135.744, confidence interval: 27.055-681.074; p<0.005). Conclusion: Iron deficiency and euthyroid goiter are common subclinical conditions in the Turkish population. In the presence of subclinical diseases followed without treatment, the duration of drug effects may be prolonged. Prospective and more comprehensive studies are needed on this subject.

Comparative study of fractional flow reserve and diastolic pressure ratio using a guidewire with a sensor for measuring intravascular pressure

This study aimed to evaluate the correlation and diagnostic agreement between diastolic pressure ratio (dPR) and fractional flow reserve (FFR) in a Japanese real-world setting. Prospective multicenter observational study. This study included 100 patients with intermediate coronary artery stenosis at 4 Japanese hospitals. For these lesions, FFR and dPR were measured using a guidewire with a sensor and a monitor to measure intravascular pressure. The correlation and diagnostic agreement between FFR and dPR were assessed. When both FFR and dPR were negative or positive, the results were considered to be concordant. When one was positive and the other was negative, the result was regarded as discordant (positive discordance, FFR > 0.80 and dPR ≤ 0.89; negative discordance, FFR ≤ 0.80 and dPR > 0.89). Overall, the FFR and dPR were well-correlated (R = 0.841). FFR and dPR were concordant in 89% of cases (concordant normal, 43%; concordant abnormal, 46%) and discordant in 11% (positive discordance, 7%; negative discordance, 4%). No significant difference was observed in the rate of concordant results between patients with and without diabetes mellitus. The diagnostic concordance rate was significantly different among the 3 coronary arteries (right coronary artery, 93.3%; left anterior descending artery, 93.2%; and left circumflex artery, 58.3%; P = .001). Additionally, the rate of concordant results tended to be higher when using intravenous administration of adenosine than when using intracoronary bolus injection of nicorandil (adenosine, 95.1%; nicorandil, 84.7%; P = .103). We found that dPR was highly correlated with FFR, and diagnostic discordance was observed in 11% of the lesions. Several factors, including lesion location and medication for hyperemia, may cause the diagnostic discordance between dPR and FFR.

Impact of Adenosine on Wavefront Propagation in Persistent Atrial Fibrillation: Insights From Global Noncontact Charge Density Mapping of the Left Atrium.

BackgroundAdenosine shortens action potential duration and refractoriness and provokes atrial fibrillation. This study aimed to evaluate the effect of adenosine on mechanisms of wavefront propagation during atrial fibrillation.Methods and ResultsThe study included 22 patients undergoing catheter ablation for persistent atrial fibrillation. Left atrial mapping was performed using the AcQMap charge density system before and after administration of intravenous adenosine at 1 or more of 3 time points during the procedure (before pulmonary vein isolation, after pulmonary vein isolation, and after nonpulmonary vein isolation ablation). Wave‐front propagation patterns were evaluated allowing identification and quantification of localized rotational activation (LRA), localized irregular activation, and focal firing. Additional signal processing was performed to identify phase singularities and calculate global atrial fibrillation cycle length and dominant frequency. A total of 35 paired maps were analyzed. Adenosine shortened mean atrial fibrillation cycle length from 181.7±14.3 to 165.1±16.3, (mean difference 16.6 ms; 95% CI, 11.3–21.9, P<0.0005) and increased dominant frequency from 6.0±0.7 Hz to 6.6±0.8 Hz (95% CI, 0.4–0.9, P<0.0005). This was associated with a 50% increase in the number of LRA occurrences (16.1±7.6–24.2±8.1; mean difference 8.1, 95% CI, 4.1–12, P<0.0005) as well as a 20% increase in the number of phase singularities detected (30.1±7.8–36.6±9.3; mean difference 6.5; 95% CI, 2.6–10.0, P=0.002). The percentage of left atrial surface area with LRA increased with adenosine and 42 of 70 zones (60%) with highest density of LRA coincided with high density LRA zones at baseline with only 28% stable across multiple maps.ConclusionsAdenosine accelerates atrial fibrillation and promotes rotational activation patterns with no impact on focal activation. There is little evidence that rotational activation seen with adenosine represents promising targets for ablation aimed at sites of stable arrhythmogenic sources in the left atrium.

An Adult Patient with Seizure and Supraventricular Tachycardia (SVT) - Occam’s Razor or Hickam’s Dictum

This is a case report describing a young lady presenting with both seizure and supraventricular tachycardia (SVT) to the emergency department (ED). She was previously well, asymptomatic with no risk factors for both conditions. A 33-year-old lady presented to the emergency department (ED) with her first episode of seizure. She was found in the kitchen with up rolling of eyes, jerking of all four limbs which self-aborted after two minutes. Electrocardiogram (ECG) performed showed supraventricular tachycardia, which reverted to sinus rhythm after administration of intravenous adenosine. Post conversion ECG showed normal sinus rhythm, absence of pre-excitation and normal QTc. Laboratory tests and computed tomography of the brain were normal. This case highlights the complex relationship between seizure and cardiac arrhythmia. SVT and seizure occurring at the same time is unusual. Clinicians need to rule out hypoxic convulsions. Epilepsy and seizures could also have a profound effect on cardiac function. Drug therapy for epilepsy is not without influence on heart rhythm. Both alcohol and illicit drugs could also precipitate concurrent seizure and SVT. Is this a case of Occam’s razor or Hickam’s dictum?

Involvement of adenosine signaling pathway in migraine pathophysiology: A systematic review of clinical studies.

To systematically review clinical studies investigating the involvement of adenosine and its receptors in migraine pathophysiology. Adenosine is a purinergic signaling molecule, clinically used in cardiac imaging during stress tests. Headache is a frequent adverse event after intravenous adenosine administration. Migraine headache relief is reported after intake of adenosine receptor antagonist, caffeine. These findings suggest a possible involvement of adenosine signaling in migraine pathophysiology and its potential as a drug target. A search through PubMed and EMBASE was undertaken for clinical studies investigating the role of adenosine and its receptors in migraine, published until September 2021. A total of 2510 studies were screened by title and abstract. Of these, seven clinical studies were included. The main findings were that adenosine infusion induced headache, and plasma adenosine levels were elevated during ictal compared to interictal periods in migraine patients. The present systematic review emphasizes a potentially important role of adenosine signaling in migraine pathogenesis. Further randomized and placebo-controlled clinical investigations applying adenosine receptors modulators in migraine patients are needed to further understand the adenosine involvement in migraine.

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

AimsWe 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 ResultsCoronary 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 (R2 = 0.757, p < 0.001). There was no correlation between respiratory rate and variations in resting Pd/Pa. When single‐beat averages were used to calculate FFR, mean ΔFFR was 0.04 ± 0.02. With averaging of FFR over three or five cardiac cycles, mean ΔFFR decreased to 0.02 ± 0.02, and 0.01 ± 0.01, respectively. Using a FFR ≤ 0.80 threshold, stenosis classification changed in 20.5% (8/39), 12.8% (5/39) and 5.1% (2/39) for single‐beat, three‐beat and five‐beat averaged FFR. The impact of respiration was more pronounced in patients with pulmonary disease (ΔFFR 0.05 ± 0.02 vs 0.03 ± 0.02, p = 0.021).ConclusionBeat‐to‐beat variations in FFR during plateau hyperemia related to respiration are common, of clinically relevant magnitude, and frequently lead FFR to cross treatment thresholds. A five‐beat averaged FFR, overcomes clinically relevant impact of FFR variation.

Adenosine-induced ventricular fibrillation in a patient with supraventricular tachycardia.

Adenosine is frequently used for paroxysmal supraventricular tachycardia (PSVT) treatment in the emergency department (ED). Atrial and ventricular pro-arrhythmic effects of adenosine were described in the literature, but ventricular fibrillation (VF) secondary to adenosine administration was rarely reported (with an incidence of < 1%). Reported herein is the first case of a 72-year-old female patient who developed VF hemodynamic collapse after an intravenous administration of adenosine for PSVT treatment. She had no known pre-excitation or accessory pathway, nor any underlying structural heart disease or prolonged QT syndrome. Raising awareness of this potential life-threatening pro-arrhythmic effect of adenosine is important, given its frequent use for PSVT treatment in the ED.

The Effectiveness of Adenosine in Treating the Acute Attacks of Supra-ventricular Tachycardia

Background: Adenosine is a natural adenine nucleoside available endogenously that decreases heart beat by blocking atrioventricular (AV) node transiently so that extend the duration of conduction in (AV) node when injected intravenously. It has a curative value in the conversion of majority of supraventricular tachycardia (SVT) to sinus rhythm. In order to evaluate the adenosine in the management of arrhythmias we conduct this study. Objective: This study was conducted to evaluate the safety and efficacy of intravenous adenosine therapy for treatment of (SVT), to determine the optimal adenosine dose effective in (SVT), and to determine the underlying conditions affecting the effective dose. And to evaluate the effectiveness of vagal maneuvers in terminating of spontaneous SVT patients and methods: A cross-sectional study conducts in a group consist of 69 patients ranged from 23-70 years old admitted to the Coronary care unit in Azadi Teaching Hospital ,in Kirkuk city, from July 2014 to June 2016. The diagnosis of (SVT) was made by present of tachycardia which is of narrow complex with a heart beat rate greater than 140 beats/ min by 12 leads chest electrocardiography (ECG). In patients who are hemodynamically stable, vagal maneuvers were carried out initially in the form of carotid sinus massage, gag reflex and Valsalva maneuver, if this failed intravenous administration of adenosine as recommended doses were preformed. If three doses of adenosine boluses were unsuccessful to convert the arrhythmia, patients were managed with other available antiarrythmias or managed with direct electrical cardio version (DC). In unstable patients were managed with (DC). Results: Of 69 included patients, diagnosed as (SVT), M: F ratio was 1:2.1. Their age ranged from 23 years to 70 years with mean age of 57 years. Vagal maneuvers (VM) resulted in restoration of sinus rhythm (SR) in 8patients (7.6%). Out of 57 episodes of (SVT), Adenosine was effective in reverting 51 episodes of SVT to sinus rhythm (89.5%). Of those converted, 18 required a single dose (6mg) (31.6%), fifteen required one additional (12mg) dose (26.3%), and another 18 required two additional doses (81mg) (31.6%).four patients were hemo-dynamically unstable (systolic blood pressure <90 mm Hg) which required (DC). Six patients (10.5%) not responding to full adenosine dose(81mg), started treatment with other medication, 1 with verapamil, 4 with amiodarone, and1 with digoxin. All of them were successfully treated. Conclusions: Adenosine is an effective medicine in treating (SVT) in those patients in whom vagal maneuvers has unsuccessful. It demonstrates a high rate of success in terminating acute attack of SVT. A higher dose may be required in majority of patients specially

Instantaneous wave-free ratio compared with fractional flow reserve in PCI: A cost-minimization analysis

BackgroundCoronary physiology is a routine diagnostic tool when assessing whether coronary revascularization is indicated. The iFR-SWEDEHEART trial demonstrated similar clinical outcomes when using instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) to guide revascularization. The objective of this analysis was to assess a cost-minimization analysis of iFR-guided compared with FFR-guided revascularization. MethodsIn this cost-minimization analysis we used a decision-tree model from a healthcare perspective with a time-horizon of one year to estimate the cost difference between iFR and FFR in a Nordic setting and a United States (US) setting. Treatment pathways and health care utilizations were constructed from the iFR-SWEDEHEART trial. Unit cost for revascularization and myocardial infarction in the Nordic setting and US setting were derived from the Nordic diagnosis-related group versus Medicare cost data. Unit cost of intravenous adenosine administration and cost per stent placed were based on the average costs from the enrolled centers in the iFR-SWEDEHEART trial. Deterministic and probabilistic sensitivity analyses were carried out to test the robustness of the result. ResultsThe cost-minimization analysis demonstrated a cost saving per patient of $681 (95% CI: $641 - $723) in the Nordic setting and $1024 (95% CI: $934 - $1114) in the US setting, when using iFR-guided compared with FFR-guided revascularization. The results were not sensitive to changes in uncertain parameters or assumptions. ConclusionsIFR-guided revascularization is associated with significant savings in cost compared with FFR-guided revascularization.

Ultra-high density mapping to characterize effective cryoballoon ablation of roof line in persistent atrial fibrillation: a pilot study

Abstract Funding Acknowledgements Type of funding sources: None. Background Roof Posterior Wall (RPW) debulking may be important in the maintenance of AF activity as reducing the surface area below a critical mass can prevent persistent AF. No data exists on a combined cryoballoon ablation (CBA) approach guided by ultra-high density mapping (UHDM) system. Objective To explore, through UHDM, generation of consistent linear lesions at the left atrial (LA) roof using CBA in patients (pts) with persistent AF. Methods Once PVI was completed, the CB (Arctic Front Advance) was used to perform RPW isolation (RPWI). CBA was applied to create a continuous lesion connecting the ostial areas of the right and left superior PVs. Optimal position of the CB along the different segments of the RPW was obtained by advancing/retracting the inner lumen catheter distally/proximally within the PV. A detailed pre- and post-ablation 3D map was created in each pt using the Orion catheter and the Rhythmia UHDM system. Areas and type of isolation over the RPW and the entire LA were precisely identified and measured. Ablation endpoint was PVI and RPWI as assessed by entrance and exit block and after administration of intravenous adenosine. Results Ten consecutive pts were included (mean LA volume = 126 ± 36 ml, mean points per map = 10800 ± 8500, mean roof area = 22 ± 4 cm²). A mean of 4.6 ± 0.8 freezes at PV and 5.4 ± 2 at the roof per pt were required (mean nadir temperature (T) = −45°C ± 6°C and −41°C ± 3°C, respectively, mean T at the roof = −33°C ± 4°C) during a mean CBA time of 954 ± 73 s for PVs and 810 ± 311 s for the roof. The mean conduction delay along the roof line at the shortest segment was 55 ± 13 ms. Resulting low-voltage areas (&amp;lt;0.1 mV, 12 ± 4cm², 53% of the roof area) and complete electrical quiescence areas (&amp;lt;0.05 mV, 8 ± 3cm², 32% of the roof area) correlated well with the linear roofline of CB positions. At the first pass all PVs were successfully isolated in all study pts. In two cases at the RPWs UHDM revealed a small conductive corridor (&amp;lt;0.1 mV) along a posterior takeoff that required adjunct RFA to complete RPW isolation. No complications were reported. Conclusions In our preliminary experience PVI plus RPWI can be achieved safely and effectively using the CB in conjunction with UHDM. The use of UHDM allowed a precise definition of the effective isolation areas.

Diagnostic utility and safety of intracoronary nicorandil as a hyperemic agent for the measurement of fractional flow reserve

We investigated the diagnostic utility and safety of intracoronary bolus administration of nicorandil compared with intravenous administration of adenosine for evaluating FFR in patients with intermediate (40–70%) coronary stenosis. The FFR values obtained with nicorandil and adenosine showed linear relationship. This correlation is statistically significant with regression coefficient of 0.932 (R2 = 0.834, p < 0.001). The side effects such as bronchospasm, hypotension, and bradycardia were significantly higher after administration of adenosine compared to nicorandil (20% vs. 1.66%, p = 0.001). Intracoronary use of nicorandil seems to be promising in offering the advantages of lesser side effects, similar efficacy, and lesser cost as compared to adenosine.

Contrast medium Pd/Pa ratio in comparison to fractional flow reserve, quantitative flow ratio and instantaneous wave-free ratio for evaluation of intermediate coronary lesions.

IntroductionContrast medium Pd/Pa ratio (cFFR) was introduced as an alternative to fractional flow reserve (FFR).AimTo assess the accuracy of cFFR in predicting of FFR, quantitative flow ratio (QFR) and instantaneous wave-free ratio (iFR).Material and methodsResting Pd/Pa, cFFR, FFR, QFR, and iFR were measured in 110 intermediate coronary lesions. cFFR was obtained after intracoronary injection of contrast medium. FFR was measured after the intravenous administration of adenosine. QFR was derived from fixed empiric hyperemic flow velocity based on coronary angiography. iFR was calculated by measuring the resting pressure gradient across a coronary lesion during diastole.ResultsForty-four patients with 110 intermediate coronary lesions were enrolled. Mean baseline Pd/Pa was 0.93 ±0.05. Mean cFFR value was similar to FFR value (0.83 ±0.09 vs. 0.81 ±0.09; p = 0.13) and QFR (0.81 ±0.1; p = 0.69) and iFR (0.90 ±0.07; p = 0.1). A total of 46 vessels (41.8%) had FFR ≤ 0.80, 50 (45.5%) vessels had cFFR ≤ 0.83, 44 (40.0%) vessels had QFR ≤ 0.80, and 38 (34.5%) vessels had iFR ≤ 0.89. An excellent agreement between cFFR and resting Pd/Pa, FFR, QFR, and iFR was confirmed (intraclass correlation coefficients of 0.83, 0.99, 0.98, and 0.88, respectively). The optimal cutoff value of cFFR was 0.83 for prediction of FFR ≤ 0.80 with sensitivity, specificity, and accuracy of 96.9%, 97.8%, and 97.3%, respectively. 100% sensitivity was observed for a cutoff value of 0.82 and 100% specificity for a cutoff value of 0.84; AUC = 0.998 (0.995–1.00); p < 0.001.ConclusionsContrast medium Pd/Pa ratio seems to be accurate in predicting the functional significance of borderline coronary lesions assessed with FFR, iFR, and QFR.

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

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. We aim to investigate the relationship between intracoronary adenosine and intravenous adenosine to determine FFR. We performed a lesion-level meta-analysis to compare intracoronary adenosine with intravenous adenosine (140 µg/kg per minute) for FFR assessment. The search was conducted in accordance to the Preferred Reporting for Systematic Reviews and Meta-Analysis statement. Lesion-level data were obtained by contacting the respective authors or by digitization of scatterplots using custom-made software. Intracoronary adenosine dose was defined as; low: <40 µg, intermediate: 40 to 99 µg, and high: ≥100 µg. We collected 1972 FFR measurements (1413 lesions) comparing intracoronary with intravenous adenosine from 16 studies. There was a strong correlation (correlation coefficient =0.915; P<0.001) between intracoronary-FFR and intravenous-FFR. Mean FFR was 0.81±0.11 for intracoronary adenosine and 0.81±0.11 for intravenous adenosine (P<0.001). We documented a nonclinically relevant mean difference of 0.006 (limits of agreement: -0.066 to 0.078) between the methods. When stratified by the intracoronary adenosine dose, mean differences between intracoronary and intravenous-FFR amounted to 0.004, 0.011, or 0.000 FFR units for low-dose, intermediate-dose, and high-dose intracoronary adenosine, respectively. The present study documents clinically irrelevant differences in FFR values obtained with intracoronary versus intravenous adenosine. Intracoronary adenosine hence confers a practical and patient-friendly alternative for intravenous adenosine for FFR assessment.

P6573Adenosine plasma levels may determine tilt table test outcome in syncopal patients with prodromal symptoms

Abstract Background/Introduction Head-up tilt table test (HUTT) and Adenosine test (ADT) are tools frequently used in the diagnostic workup of syncope. It has been suggested that patient responses to HUTT and ADT can be related to the plasma levels of Adenosine (ADPL) and Adenosine receptors (ADR). However, the exact type of association and the role of (ADPL) and ADR levels in the risk stratification and management of patients with syncope has not yet been clarified. Purpose We sought to assess the ADPL and ADR levels in patients without structural heart disease who underwent HUTT and ADT tests as part of the diagnostic workup of syncope. We specifically investigated differences with regards to the presence of a history of prodromal symptoms. Methods HUTT and ADT were performed as per the standard protocols. ADT was considered positive in the event of asystole &gt;6 seconds or heart block for &gt;10 seconds after intravenous Adenosine administration in a supine position at a dose of 0.15 mg/kg. ADPL were assessed at three timepoints during the HUTT: in the supine position, immediately after bed tilt and, in cases of a positive test, at the time of syncope. Furthermore, we assessed the A2A ADR of monocytes in the study patients. Results We prospectively analyzed 77 patients (48 women, age 47.05±21.10 years). ADT was positive in 16.7% of patients and HUTT in 49.4% of patients. ADPL in the supine position did not differ between patients with negative vs. positive ADT but showed a significant correlation with the body mass index (p=0.002). There was a trend for reduced ADPL at the tilt phase in patients with positive HUTT (0.32±0.89 vs. 0.42±0.77 ppm/Um/L, p=0.09). Of all patients, 60 (77.9%, 41 women, age 46.80±21.83 years) had reported a history of prodromal symptoms at syncope. In the subset of patients with prodromal symptoms, the ADL at the tilt phase were lower in patients with positive vs. negative HUTT (0.15±0.23 vs. 0.51±0.89, p&lt;0.05). ADR did not differ among groups but showed a significant correlation with the ADL during syncope in patients with prodromal symptoms (p&lt;0.05). Conclusion(s) Patients with prodromal symptoms and a positive HUTT demonstrate reduced ADPL at the tilt phase of HUTT preceding syncope. In these patients, ADPL in syncope correlate with the ADR. Adenosine plasma levels and receptors warrant further investigation and may predict the response to HUTT thereby contributing to the diagnostic evaluation and risk stratification of patients with syncope.

TCT-622 Respiration-Related Variations in Pd/Pa Ratio and Fractional Flow Reserve in Resting Conditions and During Intravenous Adenosine Administration

TCT-622 Respiration-Related Variations in Pd/Pa Ratio and Fractional Flow Reserve in Resting Conditions and During Intravenous Adenosine Administration

Regulation of human brown adipose tissue by adenosine and A2A receptors \u2013 studies with [15O]H2O and [11C]TMSX PET/CT

PurposeBrown adipose tissue (BAT) has emerged as a potential target to combat obesity and diabetes, but novel strategies to activate BAT are needed. Adenosine and A2A receptor (A2AR) agonism activate BAT in rodents, and endogenous adenosine is released locally in BAT as a by-product of noradrenaline, but physiological data from humans is lacking. The purpose of this pilot study was to investigate the effects of exogenous adenosine on human BAT perfusion, and to determine the density of A2ARs in human BAT in vivo for the first time, using PET/CT imaging.MethodsHealthy, lean men (n = 10) participated in PET/CT imaging with two radioligands. Perfusion of BAT, white adipose tissue (WAT) and muscle was quantified with [15O]H2O at baseline, during cold exposure and during intravenous administration of adenosine. A2AR density of the tissues was quantified with [11C]TMSX at baseline and during cold exposure.ResultsAdenosine increased the perfusion of BAT even more than cold exposure (baseline 8.3 ± 4.5, cold 19.6 ± 9.3, adenosine 28.6 ± 7.9 ml/100 g/min, p < 0.01). Distribution volume of [11C]TMSX in BAT was significantly lower during cold exposure compared to baseline. In cold, low [11C]TMSX binding coincided with high concentrations of noradrenaline.ConclusionsAdenosine administration caused a maximal perfusion effect in human supraclavicular BAT, indicating increased oxidative metabolism. Cold exposure increased noradrenaline concentrations and decreased the density of A2AR available for radioligand binding in BAT, suggesting augmented release of endogenous adenosine. Our results show that adenosine and A2AR are relevant for activation of human BAT, and A2AR provides a future target for enhancing BAT metabolism.