Comparison of the intracoronary continuous infusion method using a microcatheter and the intravenous continuous adenosine infusion method for inducing maximal hyperemia for fractional flow reserve measurement

Continuous intracoronary versus standard intravenous infusion of adenosine for fractional flow reserve assessment: the HYPEREMIC trial

AIMS

The aim of this study was to evaluate the accuracy of a continuous intracoronary (IC) adenosine infusion, administered through the novel HYPEREM™IC over-the-wire microcatheter, to measure fractional flow reserve (FFR).

METHODS AND RESULTS

The HYPEREMIC trial was a randomised, non-inferiority, crossover study in which patients with intermediate coronary lesions were enrolled for sequential pressure wire studies. FFR was measured using intravenous (IV) (140-180 mcg/kg/min) versus continuous non-weight-adjusted IC (360 mcg/min) adenosine. Patients were randomised and blinded to the order in which they received the adenosine, separated by a washout period. The primary endpoint was the mean hyperaemic FFR. Forty-one patients were enrolled at three UK sites between June and November 2016. The mean (standard deviation) FFR was 0.82 (±0.09) after IC versus 0.84 (±0.09) after IV adenosine. The difference of -0.02 (95% confidence interval [CI]: -0.03 to -0.01) confirmed the non-inferiority (margin <0.05) of IC to IV adenosine. Intracoronary adenosine was associated with a shorter mean time to maximal hyperaemia (difference -44 [95% CI: -59 to -29] seconds; p<0.0001). Chest discomfort was reported in 32/41 (78.0%) patients during IV adenosine versus 12/41 (29.3%) patients during IC adenosine.

CONCLUSIONS

Continuous IC adenosine was a reliable, faster and better tolerated method of achieving maximal hyperaemia compared to IV adenosine.

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. We aim to investigate the relationship between intracoronary adenosine and intravenous adenosine to determine FFR.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Comparison of intracoronary versus intravenous adenosine-induced maximal hyperemia for fractional flow reserve measurement: A systematic review and meta-analysis

OBJECTIVE

We sought to perform a systematic review and meta-analysis of the available literature comparing fractional flow reserve (FFR) measurements after administration of adenosine using intracoronary (IC) bolus versus standard continuous intravenous (IV) infusion.

BACKGROUND

FFR is considered the gold standard for invasive assessment of coronary lesions of intermediate severity. IV adenosine is recommended to induce hyperemia; however, IC adenosine is widely used for convenience. The difference between IV and IC administration in lesions assessment is not well studied.

METHODS

We systematically searched MEDLINE and relevant databases for studies comparing IV with IC adenosine administration for FFR measurement. We reviewed data pertaining to adenosine doses, side effects, and FFR values.

RESULTS

Eight studies addressing the primary question were identified. Dose of IC adenosine varied between 36 and 600 μg. Compared to IV adenosine infusion, the sensitivity of IC administration is 0.805 (95% confidence interval [95% CI]: 0.664-0.896; p < .001), specificity is 0.965 (95% CI: 0.932-0.983; p < .001), positive likelihood ratio is 24.218 (95% CI: 12,263-47.830; p < .001), negative likelihood ratio is 0.117 (95% CI: 0.033-0.411; p < .01), and diagnostic odds ratio is 274.225 [95% CI: 92.731-810.946; p < .001]. Overall, hemodynamic side effects and symptoms were reported more frequently with IV adenosine.

CONCLUSIONS

The available literature suggests that IC adenosine is well tolerated and may provide equivalent diagnostic accuracy compared to IV administration. However, variability in dosing regimens does not allow definitive conclusions regarding noninferiority of IC approach compared to IV administration.

Intravascular ultrasound characteristics in patients with intermediate coronary lesions and borderline fractional flow reserve measurements

Revascularization of borderline fractional flow reserve (FFR) is controversial and the morphologic characteristics of borderline FFR lesions are not well known. The objective of this study was to determine the intravascular ultrasound (IVUS) characteristics in intermediate coronary lesions with borderline FFR in patients with intermediate coronary artery stenosis (40%-70% diameter stenosis).Both IVUS and FFR were performed in a total of 228 left anterior descending arteries. We divided them into 3 groups by FFR value: ischemic (n = 46, FFR < 0.75), borderline (n = 71, FFR 0.75 to ≤0.80), and non-ischemic (n = 111, FFR > 0.80). We compared the IVUS parameters, including minimum lumen area, lesion length, plaque burden, and volumetric analysis among the 3 groups.In the IVUS analysis, the minimum lumen area was smaller (2.5 ± 0.6 vs. 2.7 ± 0.7 vs. 3.4 ± 1.2 mm, P < .001); lesion length was longer (23.6 ± 8.4 vs. 23.6 ± 7.4 vs. 17.4 ± 6.8 mm, P < .001); plaque burden was larger (76.1 ± 9.6 vs. 73.9 ± 7.5 vs. 69.8 ± 9.5%, P < .001); plaque volume was larger (173.0 ± 78.3 vs. 167.7 ± 75.0 vs. 129.5 ± 79.1 mm, P < .01); and percent atheroma volume was larger (57.9 ± 7.5 vs. 57.6 ± 6.6 vs. 53.9 ± 8.0%, P < .01) in the ischemic and borderline groups compared with the non-ischemic group, respectively. However, post-hoc analyses showed there were no significant differences between the ischemic and borderline group for all IVUS parameters.There were no differences in IVUS characteristics between borderline and functionally significant FFR, but the amount of atheromatous plaque was more severe in these 2 groups than in the non-ischemic group.

Intracoronary versus intravenous adenosine to assess fractional flow reserve: a systematic review and meta-analysis

AIMS

Intravenous infusion of adenosine is the reference method to measure fractional flow reserve (FFR). Intracoronary boluses are often used because of time and convenience, but their effectiveness has yet to be assessed.

METHODS

We conducted a systematic review and meta-analysis of prospective studies directly comparing intravenous and intracoronary adenosine administration for FFR measurement. FFR values and prevalence of functionally critical lesions obtained with the different methods of adenosine administration were compared.

RESULTS

Twelve studies evaluating 781 lesions from 731 patients were included (63.7 years, 25.5% women, median FFR 0.82). FFR values were significantly lower with intravenous adenosine than with intracoronary adenosine [mean difference 0.01, 95% confidence interval (CI) 0.00-0.02, P = 0.005], even if no significant differences were observed when only high doses of intracoronary adenosine (≥150 μg) were considered. The prevalence of functionally critical lesions did not significantly differ between intracoronary and intravenous adenosine. Concerning the use of different doses of intracoronary adenosine, low doses (≤60 μg) were associated with higher FFR values (mean difference 0.02, 95% CI 0.01-0.03, P < 0.001) and fewer functionally critical lesions (OR 0.57, 95% CI 0.40-0.81, P = 0.002) compared with high doses. Meta-regression analysis did not show any significant interaction between the way of adenosine administration and main clinical features. Intracoronary adenosine was associated with a higher incidence of atrioventricular blocks, whereas angina and/or systemic symptoms were more frequent with intravenous adenosine.

CONCLUSION

Intracoronary adenosine might be as effective as intravenous adenosine to measure FFR, provided that adequate doses are used. Intracoronary adenosine represents a valuable alternative to intravenous adenosine whenever appropriately administered.

Myocardial Mass Contributes to the Discrepancy Between Anatomic Stenosis Severity Assessed by Intravascular Ultrasound and Fractional Flow Reserve in Intermediate Lesions of the Coronary Artery

OBJECTIVES

The present study investigated the major contributors to the discrepancy between the minimal lumen area (MLA) and fractional flow reserve (FFR).

BACKGROUND

There was considerable discrepancy between MLA or diameter stenosis (DS) and FFR.

METHODS

We enrolled 744 patients with intermediate stenoses of the left anterior descending artery (LAD). Summed epicardial coronary artery length distal to the target stenosis was obtained from each longest view of the vessels on the coronary angiograms. Mismatching was defined as a lesion with FFR of >0.80 and MLA smaller than the best cut-off value (BCV) for predicting FFR of ≤0.80. Reverse mismatching was defined as a lesion with FFR of ≤0.80 and MLA larger than the BCV.

RESULTS

Summed epicardial coronary artery length was longer at the lesions of proximal LAD than that of middle LAD (380 mm ± 82 mm vs. 341 mm ± 80 mm, P < 0.001). Reverse mismatching was found more frequently in the proximal than middle LAD (28.3% vs. 5.5%, P < 0.001). Independent predictors of FFR ≤ 0.80 were age, male, multi-vessel disease, proximal LAD lesion, MLA, DS, plaque burden at distal reference, lesion length and summed epicardial coronary artery length. Proximal LAD lesion was an independent predictor of reverse mismatching (hazard ratio 3.162, 1.858-5.382, P < 0.001).

CONCLUSIONS

Myocardial mass subtended by a lesion is an important factor predicting FFR ≤0.80 and discrepancy between FFR and MLA. Myocardial mass subtended by a lesion should be considered when determining the revascularization therapy by intravascular ultrasound parameters. © 2017 Wiley Periodicals, Inc.

Meta-Analysis of Head-to-Head Comparison of Intracoronary Versus Intravenous Adenosine for the Assessment of Fractional Flow Reserve

Intravenous (IV) infusion of adenosine represents the gold standard for measuring fractional flow reserve (FFR). However, IV adenosine is more expensive and time-consuming compared with intracoronary (IC) boluses of adenosine. We conducted a meta-analysis of studies comparing IC with IV adenosine for FFR assessment in the same coronary lesions. We searched for studies comparing IC with IV adenosine and reporting absolute FFR values or rate of abnormal FFR for both routes. Prespecified subgroup analysis was performed to appraise studies using low-dose (<100 μg) or high-dose IC adenosine (≥100 μg). We retrieved 11 studies amounting to 587 patients and 621 lesions. Six studies evaluated low-dose IC boluses (15 to 80 μg) and 5 studies high-dose boluses (120 to 600 μg). Absolute FFR values were slightly, yet significantly lower with IV adenosine compared with IC adenosine (mean difference 0.02, 95% confidence interval [CI] 0.00 to 0.03, p = 0.02). This difference, however, did not translate into a significant difference in the rate of abnormal FFR between IC and IV adenosine (hazard ratio 0.93, 95% CI 0.76 to 1.13, p = 0.57); moreover, no statistically significant difference was observed between low-dose and high-dose IC adenosine subgroups. Adverse events were less frequent with IC adenosine compared with IV adenosine (risk ratio 0.17, 95% CI 0.07 to 0.43, p <0.001). In conclusion, IC administration of adenosine, although inducing a slightly lower amount of hyperemia compared with IV infusion of adenosine, yields a similar diagnostic accuracy in identifying hemodynamically significant coronary stenosis and is better tolerated by the patients.

The impact of microvascular resistance on the discordance between anatomical and functional evaluations of intermediate coronary disease

AIMS

In intermediate coronary artery disease, discordance between anatomical and functional assessments persists and the diagnostic accuracy of an anatomical evaluation is not satisfactory for determining functional significance. We aimed to evaluate the impact of microvascular resistance on "anatomical-functional discordance".

METHODS AND RESULTS

In 97 intermediate coronary lesions of 83 patients, minimum lumen area (MLA), fractional flow reserve (FFR), Δ(Pd/Pa-FFR), and hyperaemic microvascular resistance index (hMVRI) were measured using intravascular ultrasound and an intracoronary dual pressure and Doppler sensor-tipped guidewire. hMVRI correlated with FFR and Δ(Pd/Pa-FFR) (r=0.611, p<0.001; r=-0.509, p<0.001; respectively). After the lesions were categorised into four groups based on functional significance (FFR 0.8) and the MLA cut-off for that (2.5 mm2), hMVRI was higher with a lower Δ(Pd/Pa-FFR) regardless of the MLA group in lesions with FFR >0.8, compared with those in lesions with FFR ≤0.8. hMVRI was independently associated with FFR and Δ(Pd/Pa-FFR) (β=0.443, p<0.001; β=-0.389, p<0.001; respectively).

CONCLUSIONS

Coronary microvascular resistance is associated with anatomical-functional discordance and the ischaemic potential of intermediate epicardial stenosis. In determining a treatment strategy, anatomy alone is insufficient and an integrated physiologic approach is important.

Clinical Outcomes in Patients with Deferred Coronary Lesions according to Disease Severity Assessed by Fractional Flow Reserve

Data on the clinical outcomes in deferred coronary lesions according to functional severity have been limited. This study evaluated the clinical outcomes of deferred lesions according to fractional flow reserve (FFR) grade using Korean FFR registry data. Among 1,294 patients and 1,628 lesions in Korean FFR registry, 665 patients with 781 deferred lesions were included in this study. All participants were consecutively categorized into 4 groups according to FFR; group 1: ≥ 0.96 (n = 56), group 2: 0.86-0.95 (n = 330), group 3: 0.81-0.85 (n = 170), and group 4: ≤ 0.80 (n = 99). Primary endpoint was major adverse cardiac events (MACE), a composite of all-cause death, myocardial infarction, and target vessel revascularization. The median follow-up period was 2.1 years. During follow-up, the incidence of MACE in groups 1-4 was 1.8%, 7.6%, 8.8%, and 13.1%, respectively. Compared to group 1, the cumulative rate by Kaplan-Meier analysis of MACE was not different for groups 2 and 3. However, group 4 had higher cumulative rate of MACE compared to group 1 (log-rank P = 0.013). In the multivariate Cox hazard models, only FFR (hazard ratio [HR], 0.95; P = 0.005) was independently associated with MACE among all participants. In contrast, previous history of percutaneous coronary intervention (HR, 2.37; P = 0.023) and diagnosis of acute coronary syndrome (ACS) (HR, 2.35; P = 0.015), but not FFR, were independent predictors for MACE in subjects with non-ischemic (FFR ≥ 0.81) deferred coronary lesions. Compared to subjects with ischemic deferred lesions, clinical outcomes in subjects with non-ischemic deferred lesions according to functional severity are favorable. However, longer-term follow-up may be necessary.

Physiologic Assessment of Coronary Artery Disease: Focus on Fractional Flow Reserve

The presence of myocardial ischemia is the most important prognostic factor in patients with ischemic heart disease. Fractional flow reserve (FFR) is a gold standard invasive method used to detect the stenosis-specific myocardial ischemia. FFR-guided revascularization strategy is superior to angiography-guided strategy. The recently developed hyperemia-free index, instantaneous wave free ratio is being actively investigated. A non-invasive FFR derived from coronary CT angiography is now used in clinical practice. Due to rapid expansion of invasive and non-invasive physiologic assessment, comprehensive understanding of the role and potential pitfalls of each modality are required for its application. In this review, we focus on the basic and clinical aspects of physiologic assessment in ischemic heart disease.

Meta-analysis of deferral versus performance of coronary intervention based on coronary pressure-derived fractional flow reserve

Fractional flow reserve (FFR) has been proposed as the gold standard to assess functional severity of coronary artery stenosis and to stratify which lesions should be subjected to intervention (percutaneous coronary intervention [PCI]). A systematic review was performed in MEDLINE and EMBASE including studies indexed until November 2013 that used FFR for deferral or performance of PCI. Outcomes of interest were death, acute myocardial infarction (AMI), and new revascularization (RV). Nineteen studies were included, totaling 3,097 patients (3,796 lesions). Mean follow-up was 21.2 months. In indirect comparisons, FFR-PCI and FFR-defer groups had similar death (2.2% vs 2.0%, respectively, p = 0.86) and AMI rates (1.9% vs 1.9%, respectively, p = 1.00). RV rates were higher in the FFR-PCI group (14.0% vs 4.4%, p = 0.002). Direct comparisons (2-arm trials) also showed no differences in death (odds ratio [OR] 1.86 [95% CI 0.81 to 4.27], I(2) = 11.5, p = 0.14) and AMI rates (OR 0.75 [95% CI 0.21 to 2.69], I(2) = 47.1, p = 0.66); RV rates were again higher in the FFR-PCI (OR 3.10 [95% CI 1.25 to 7.70], I(2) = 72.2, p = 0.015). Meta-regression suggests influence of male gender on RV rates (β = 0.058, p = 0.026). In conclusion, deferral of PCI based on FFR is a safe strategy. Considerable heterogeneity was observed, however.

Relationship between intravascular ultrasound parameters and fractional flow reserve in intermediate coronary artery stenosis of left anterior descending artery: intravascular ultrasound volumetric analysis

OBJECTIVES

The objective of this study was to assess the relationship between intravascular ultrasound (IVUS) parameters, including volumetric analysis, and fractional flow reserve (FFR).

BACKGROUND

Although it is known that coronary atherosclerosis burden measured by IVUS volumetric analysis is related with clinical outcomes, its relationship with functional significance remains unknown.

METHODS

Both IVUS and FFR were performed in 206 cases of intermediate stenosis of the left anterior descending artery (LAD). Myocardial ischemia was assessed by FFR and maximal hyperemia was induced by continuous intracoronary adenosine infusion. FFR < 0.80 was considered as significant inducible myocardial ischemia. We performed standard IVUS parameter measurements and volumetric analyses. IVUS parameter comparison was performed in the presence (n = 90) or absence (n =116) of significant myocardial ischemia.

RESULTS

Lesions with minimal lumen area (MLA) ≥ 4.0 mm2 had FFR ≥ 0.80 in 91.4% of cases, while 50.9% of lesions with MLA < 4.0 mm2 had FFR < 0.80. The independent predictors of FFR < 0.80 were IVUS lesion length (odds ratio [OR]: 1.1, 95% confidence interval [CI] = 1.06–1.18, P < 0.001) and MLA significance according to the lesion location (OR: 7.01, 95% CI = 3.09–15.92, P = 0.001). FFR correlated with plaque volume (r = −0.345, P < 0.001) and percent atheroma volume (PAV) (r = −0.398, P < 0.001). Lesions with significant ischemia (FFR < 0.80) as compared to those with FFR > 0.80 were associated with larger plaque volume (181.8 ± 82.3 vs. 125.9 ± 77.9 mm3, P < 0.001) and PAV (58.9 ± 5.6 vs. 53.8 ± 7.9%, P < 0.001).

CONCLUSIONS

IVUS parameters representing severity and extent of atheromatous plaque correlated with functional significance in LAD lesions with intermediate stenosis.

Thrombus aspiration during primary percutaneous coronary intervention for preserving the index of microcirculatory resistance: a randomised study

AIMS

We aimed to investigate whether thrombus aspiration could preserve the index of microcirculatory resistance (IMR) after primary percutaneous coronary intervention (PCI) in patients with ST-elevation myocardial infarction (STEMI).

METHODS AND RESULTS

Sixty-three patients with STEMI were randomised into two groups: primary PCI after thrombus aspiration (aspiration group, n=33) and primary PCI without thrombus aspiration (non-aspiration group, n=30). IMR was measured using a pressure-temperature sensor-tipped coronary wire. Echocardiography was performed at baseline and at six-month follow-up. No significant differences in baseline ejection fraction (EF, 47.3±8.5% vs. 49.5±7.8%, p=0.281) and baseline wall motion score index (WMSI, 1.45±0.31 vs. 1.37±0.27, p=0.299) were observed between the two groups. However, significant differences in IMR (23.5±10.2 U vs. 34.2±21.7 U, p=0.018), %E2%88%86EF (follow-up EF - baseline EF; 3.33±4.6% vs. 0.73±1.9%, p=0.005), and %E2%88%86WMSI (follow-up WMSI - baseline WMSI; -0.121±0.16 vs. -0.004±0.07, p=0.001) were observed between the two groups.

CONCLUSIONS

Thrombus aspiration as an adjunctive method to primary PCI for STEMI may preserve microvascular integrity and have beneficial effects on myocardial microcirculation.

Diagnostic accuracy of intravascular ultrasound-derived minimal lumen area compared with fractional flow reserve--meta-analysis: pooled accuracy of IVUS luminal area versus FFR

INTRODUCTION

Although intravascular ultrasound minimal luminal area (IVUS-MLA) is one of many anatomic determinants of lesion severity, it has been proposed as an alternative to fractional flow reserve (FFR) to assess severity of coronary artery disease.

OBJECTIVE

Pool the diagnostic performance of IVUS-MLA and determine its overall accuracy to predict the functional significance of coronary disease using FFR (0.75 or 0.80) as the gold standard.

METHODS

Studies comparing IVUS and FFR to establish the best MLA cutoff value that correlates with significant coronary stenosis were reviewed from a Medline search using the terms "fractional flow reserve" and "ultrasound." DerSimonian Laird method was applied to obtain pooled accuracy.

RESULTS

Eleven clinical trials, including two left main (LM) trials (total N = 1,759 patients, 1,953 lesions) were included. The weighted overall mean MLA cutoff was 2.61 mm(2) in non-LM trials and 5.35 mm(2) in LM trials. For non-LM lesions, the pooled sensitivity of MLA was 0.79 (95% CI = 0.76-0.83) and specificity was 0.65 (95% CI = 0.62-0.67). Positive likelihood ratio (LR) was 2.26 (95% CI = 1.98-2.57) and LR- was 0.32 (95% CI = 0.24-0.44). Area under the summary receiver operator curve for all trials was 0.848. Pooled LM trials had better accuracy: sensitivity = 0.90, specificity = 0.90, LR+ = 8.79, and LR- = 0.120.

CONCLUSION

Given its limited pooled accuracy, IVUS-MLA's impact on clinical decision in this scenario is low and may lead to misclassification in up to 20% of the lesions. Pooled analysis points toward lower MLA cutoffs than the ones used in current practice.

Intracoronary versus intravenous adenosine-induced maximal coronary hyperemia for fractional flow reserve measurements

BACKGROUND

Maximal hyperemia is the critical prerequisite for fractional flow reserve (FFR) assessment. Despite intravenous (IV) adenosine currently being the recommended approach, intracoronary (IC) administration of adenosine constitutes a valuable alternative in everyday practice. However, it is surprisingly unclear which IC strategy allows the achievement of FFR values that are comparable to IV adenosine.

OBJECTIVES

This study sought to compare increasing doses of IC adenosine versus IV adenosine for FFR.

METHODS

30 intermediate coronary stenoses undergoing FFR measurement were prospectively and consecutively enrolled. Hyperemia was sequentially induced by bolus of IC adenosine (ADN; 150 μg) followed by IV adenosine (IVADN) infusion over 3 minutes at dose of (140 μg/kg/min). FFR values, symptoms, and development of atrioventricular block were recorded.

RESULTS

150 μg doses of IC adenosine were well tolerated and associated with fewer symptoms than IV adenosine. Intracoronary adenosine doses induced a significant decrease of FFR compared with baseline levels (P < 0.01). Among the 6 patients with FFR values less than 0.80 identified by IVADN, 4 were correctly identified also by 150 μg bolus IC adenosine. Larger randomized studies with cross-over design are necessary to verify the results.

CONCLUSIONS

This small pilot study suggests that IC adenosine might be an alternative to IV adenosine. Larger randomized studies with a cross-over design are necessary.

Comparison of hyperemic efficacy between central and peripheral venous adenosine infusion for fractional flow reserve measurement

BACKGROUND

Maximal hyperemia is a prerequisite for the accurate measurement of fractional flow reserve (FFR). Although continuous infusion of adenosine via the femoral vein is considered to be the gold standard, this requires an additional invasive procedure for femoral vein access and is difficult to use during transradial coronary catheterization. We performed this prospective study to evaluate the feasibility and efficacy of peripheral intravenous infusion of adenosine for FFR measurement.

METHODS AND RESULTS

Seventy-one patients were prospectively enrolled, and FFR was measured using a 0.014-inch coronary pressure wire. Hyperemic efficacy of adenosine was compared among intracoronary bolus injection and continuous IV infusion (140 μg/min/kg) via the femoral and via the forearm vein. In 20 patients, hyperemic mean transit time and index of microcirculatory resistance were also measured. Mean FFR after bolus administration of adenosine was 0.81±0.10. As compared with femoral vein infusion (FFR: 0.80±0.10), hyperemic efficacy of forearm vein infusion of adenosine (FFR: 0.80±0.11) was not inferior (P for noninferiority=0.01). The number of functionally significant stenoses (FFR <0.75) was also not different between the 2 methods (femoral vein versus forearm vein; 17 (25.0%) versus 17 (25.0%), P=1.0). Both hyperemic mean transit time and index of microcirculatory resistance were not different between the 2 routes of adenosine infusion. Additional bolus injection of adenosine during IV infusion did not improve the hyperemic efficacy but increased the risk of atrioventricular block.

CONCLUSIONS

This study suggests that continuous intravenous infusion of adenosine via the forearm vein is a convenient and effective way to induce steady-state hyperemia for invasive physiological measurements.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01070420.

Physiologic evaluation of myocardial bridging: a new analysis for an old disease

BACKGROUND

Myocardial bridging (MB) is the most common congenital coronary anomaly. However, the functional relevance of MB is not well understood.

METHODS

Eighteen patients with lone MB were consecutively enrolled. Fractional flow reserve (FFR) was measured before and after dobutamine infusion. Diastolic FFR was calculated by offline analysis. Cutoff values for functional significance of FFR and diastolic FFR were 0.75 and 0.76, respectively.

RESULTS

Baseline systolic percent diameter stenosis and lesion length of MB were 70 ± 16% and 24 ± 7 mm. FFR and diastolic FFR were 0.92 ± 0.05 and 0.89 ± 0.07 at maximal hyperemia induced by adenosine, respectively (P = 0.006). Despite the angiographic stenosis, only 1 lesion was functionally significant. After dobutamine infusion, percent diameter stenosis (84 ± 11%, P = 0.002) and lesion length (26 ± 6 mm, P = 0.019) were aggravated and diastolic FFR was lowered (0.84 ± 0.10, P = 0.006). Two additional lesions became functionally significant after dobutamine infusion. Angiographic percent diameter stenosis at diastole was correlated with dobutamine diastolic FFR (R = -0.58, P = 0.04), but stenosis at systole was not. During median follow-up of 54 months, 2 patients underwent target-lesion revascularization.

CONCLUSIONS

Dobutamine increased the morphologic and functional severity of MB. Dobutamine-FFR seems to be helpful in the functional assessment of MB.

Usefulness of the fractional flow reserve derived by intracoronary pressure wire for evaluating angiographically intermediate lesions in acute coronary syndrome

INTRODUCTION AND OBJECTIVES

In contrast to findings in stable ischemic heart disease, in acute coronary syndrome (ACS), measurement of the fractional flow reserve (FFR) using an intracoronary pressure wire has not been shown to be useful for evaluating angiographically equivocal coronary lesions. The aim of this study was to analyze outcomes at 1 year in ACS patients with lesions that were classed as intermediate on coronary angiography and which were not nonrevascularized because of the FFR value determined by intracoronary pressure wire.

METHODS

The observational study involved a cohort of patients admitted for ACS who had intermediate lesions on coronary angiography that were not revascularized because the FFR was >0.75. Functional studies were not carried out if there was angiographic evidence of instability. All-cause mortality, non-fatal myocardial infarction, revascularization of the target lesion and readmission for cardiac causes in the first year of the study were recorded.

RESULTS

The study included 106 patients with 127 lesions that were not revascularized because the FFR was >0.75. Their mean age was 69.9+/-10 years, 92 (86.8%) had non-ST-elevation ACS, the mean angiographic stenosis was 40.5+/-7.8%, and the mean FFR was 0.88+/-0.06. There were no complications during the procedure. The follow-up rate at 1 year was 95.1%. Events observed at 1 year were: 2 deaths (total mortality 1.9%), 0 fatal acute myocardial infarctions, 1 (0.9%) target lesion revascularization and 5 (4.7%) readmissions for cardiac causes.

CONCLUSIONS

Once lesions with clear angiographic signs of instability are excluded, intracoronary pressure wire measurement could be useful in ACS patients for avoiding unnecessary revascularization of angiographically intermediate coronary lesions.