Intracoronary Continuous Adenosine Infusion A Novel and Effective Way of Inducing Maximal Hyperemia for Fractional Flow Reserve Measurement

Comparison of efficacy and safety of intracoronary nicardipine and adenosine for fractional flow reserve assessment of coronary stenosis

BACKGROUND

Administration of intracoronary (IC) adenosine allows an easily feasible, inexpensive, and more rapid alternative method for fractional flow reserve (FFR). It is common practice in many centers worldwide. Nicardipine is a strong coronary vasodilator but its efficacy and safety for assessing FFR is not established. The purpose of present study was to compare the efficacy and safety of IC nicardipine and adenosine for assessing FFR.

METHODS

One hundred and fifty-nine patients with a total of 193 vessels undergoing clinically indicated FFR assessment of intermediate coronary stenoses were included. For the initial assessment of FFR, hyperemia was induced by an IC adenosine. After a washout period of 3 min, FFR was reassessed using 200 μg of IC nicardipine.

RESULTS

Hyperemic efficacy among two different stimuli was compared. The mean FFR with IC adenosine was 0.83 ± 0.09 and that with an IC nicardipine was 0.84 ± 0.09. The median FFR with an IC adenosine was 0.83 (0.78-0.91) and that with an IC nicardipine was 0.85 (0.79-0.91) (p-value 0.246). Both FFR values showed an excellent correlation (R² = 0.982, p < 0.001). Nicardipine produced fewer changes in heart rate, less chest pain and less flushing than adenosine. Transient atrioventricular block occurred in 29 patients with IC adenosine and none with IC nicardipine.

CONCLUSIONS

IC bolus injection of nicardipine could be introduced as a safe and practical alternative method of inducing hyperemia during FFR measurements. Compared to IC adenosine, IC nicardipine has a similar hyperemic efficacy and excellent side-effect profile.

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.

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.

Intralesional versus intracoronary administration of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention in patients with acute coronary syndromes: A meta-analysis of randomized controlled trials

BACKGROUND

Glycoprotein IIb/IIIa inhibitors (GPIs) have been regarded as an adjuvant regimen to deal with no-reflow. However, whether intralesional (IL) administration of GPIs improves myocardial reperfusion without increasing bleeding in patients with acute coronary syndrome (ACS) compared with intracoronary (IC) administration has not been well addressed. Our meta-analysis aimed to evaluate the efficacy and safety of IL versus IC administration of GPIs for patients with ACS during percutaneous coronary intervention.

METHODS

We systematically searched Medline, Embase, the Cochrane Central Register of Controlled Trials, and Cambridge Scientific Abstracts from January 2007 to May 2017. Thrombolysis in Myocardial Infarction (TIMI) 3 flow, corrected TIMI frame count (CTFC), and complete ST-segment resolution (>70%) were selected as the primary outcomes. Major adverse cardiac events (MACEs) were the secondary outcome, and major bleeding complications were the safety outcome. Data analysis was conducted using the Review Manager 5.3 software.

RESULTS

Six randomized controlled trials were included in our meta-analysis. Compared with IC, IL obtained better results in terms of TIMI grade 3 flow [odds ratio (OR) 2.29; 95% confidence intervals (CIs) 1.31-4.01; P = .004], CTFC [weighted mean difference (WMD) -4.63; 95% CI -8.82 to -0.43; P = .03], and complete ST-segment resolution (OR 1.55; 95% CI 1.12-2.14; P = .008). There was a trend toward decreased MACE in the IL administration groups, which was not of statistical significance (OR 0.63; 95% CI 0.30-1.31; P = .22). No significant difference was found between the two groups in terms of in-hospital major bleeding events (OR 2.52; 95% CI .66 to 9.62; P = .18).

CONCLUSION

IL administration yielded favorable outcomes in terms of myocardial tissue reperfusion as evidenced by the improved TIMI flow grade, CTFC, complete ST-segment resolution, and decreased MACE without increasing in-hospital major bleeding events. The IL administration of GPIs can be recommended as the preferred regimen to guard against no-reflow.

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.

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.

Impact of additional intracoronary nicorandil administration during fractional flow reserve measurement with intravenous adenosine 5'-triphosphate infusion

BACKGROUND

Fractional flow reserve (FFR) is a useful index for determining the functional severity of epicardial coronary artery stenosis as an invasive physiological method. Although intravenous adenosine 5'-triphosphate (ATP) is generally used as a hyperemic agent for FFR measurement in Japan, there are some concerns about the variability of FFR measurement (short half-life, effect of caffeine, cyclic change). It is difficult to confirm sufficient maximum hyperemia after ATP infusion. Recent studies reported that nicorandil (NIC) could be an alternative to ATP as a hyperemic agent.

METHODS

Patients who underwent FFR assessments of angiographically intermediate lesions were included. All patients were asked to refrain from caffeine-containing products more than 12hours before FFR measurements. All patients first received intravenous (IV) ATP infusion (180μg/kg/min) for 3min to measure FFR (ATP-FFR). After additional intracoronary (IC) NIC administration (2mg/30s) during ATP infusion, FFR was measured again (NIC-FFR). To check cyclic change in FFR, we measured minimum and maximum FFR values during both ATP and NIC hyperemic phase.

RESULTS

In this study, 94 patients with 94 lesions were enrolled. Mean FFR value was 0.81±0.10 in ATP-FFR infusion and 0.80±0.09 in NIC-FFR, respectively. ATP-FFR and NIC-FFR had a strong correlation on the whole (r=0.92, p<0.001). In 18 patients (19%), FFR values were significantly lower in NIC-FFR than in ATP-FFR. In one-third of those patients (6%), it was possible to change therapeutic strategy from deferral range (>0.80) to interventional range (≦0.80) after NIC-FFR measurements. Cyclic change in FFR was smaller in NIC-FFR than in ATP-FFR (0.03±0.02 vs. 0.06±0.05, p<0.0001).

CONCLUSION

Additional IC NIC might be useful to confirm sufficient maximum hyperemia after IV ATP infusion in daily clinical practice. Furthermore, IC NIC could reduce cyclic change in FFR; thus, physicians might find it easier to determine FFR value during the procedure.

Measuring Procedure and Maximal Hyperemia in the Assessment of Fractional Flow Reserve for Superficial Femoral Artery Disease

AIM

The optimal fractional flow reserve (FFR) measurement method for superficial femoral artery (SFA) lesions remains to be established. We clarified the optimal measuring procedure for FFR for SFA lesions and investigated the necessary dose of papaverine for inducing maximal hyperemia in SFA lesions.

METHODS

Forty-eight patients with SFA lesions who underwent measurement of peripheral FFR (pFFR: distal mean pressure divided by proximal mean pressure) after endovascular treatment by the contralateral femoral crossover approach were prospectively enrolled. In the pFFR measurement, a guide sheath was placed on top of the common iliac bifurcation and pressure equalization was performed. After advancing the pressure wire distal to the SFA lesion, sequential papaverine administration selectively to the affected common iliac artery was performed.

RESULTS

There were no symptoms, electrocardiogram changes, and significant pressure drops at the guide sheath tip with increasing papaverine dose. pFFR changes following 20, 30, and 40 mg of papaverine were 0.87±0.10, 0.84±0.10, and 0.84±0.10, respectively (P＜0.001). Although not significantly different, pFFR decreased more in several patients at 30 mg of papaverine than at 20 mg. The pFFR at 40 mg of papaverine was almost similar to that at 30 mg of papaverine. The necessary papaverine dose was not changed according to sex and number of run-off vessels.

CONCLUSIONS

The contralateral femoral crossover approach is useful in FFR measurement for SFA lesions, and maximal hyperemia is induced by 30 mg of papaverine.

Advances in coronary physiology

Pressure-wire technology, most typically fractional flow reserve (FFR), has provided interventional cardiologists with a means of determining the physiological importance of a stenosis during angiography. There has been renewed interest in coronary physiology in the light of guideline recognition, ongoing clinical research and new technologies changing the paradigm of how assessment is performed in the catheter laboratory. We reflect on FFR, with regards the potential effects of changing hemodynamics on FFR and the latest evidence with regards to outcomes. We also review the instantaneous wave-free ratio (iFR), a new pressure-only index, measured at rest, that is under active evaluation in several international randomized controlled trials. We review the accumulated evidence and discuss the important physiological concepts between pressure and flow that underlie the approach to using resting indices. Finally we investigate future developments, including physiological mapping with iFR-Pullback and the potential to predict the hemodynamic effect of stenting.

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.

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

BACKGROUND

Inducing stable maximal coronary hyperemia is essential for measurement of fractional flow reserve (FFR). We evaluated the efficacy of the intracoronary (IC) continuous adenosine infusion method via a microcatheter for inducing maximal coronary hyperemia.

METHODS

In 43 patients with 44 intermediate coronary lesions, FFR was measured consecutively by IC bolus adenosine injection (48-80 microg in left coronary artery, 36-60 microg in the right coronary artery) and a standard intravenous (IV) adenosine infusion (140 microg x min(-1) x kg(-1)). After completion of the IV infusion method, the tip of an IC microcatheter (Progreat Microcatheter System, Terumo, Japan) was positioned at the coronary ostium, and FFR was measured with increasing IC continuous adenosine infusion rates from 60 to 360 microg/min via the microcatheter.

RESULTS

Fractional flow reserve decreased with increasing IC adenosine infusion rates, and no further decrease was observed after 300 microg/min. All patients were well tolerated during the procedures. Fractional flow reserves measured by IC adenosine infusion with 180, 240, 300, and 360 microg/min were significantly lower than those by IV infusion (P < .05). Intracoronary infusion at 180, 240, 300, and 360 microg/min was able to shorten the times to induction of optimal and steady-stable hyperemia compared to IV infusion (P < .05). Functional significances were changed in 5 lesions by IC infusion at 240 to 360 microg/min but not by IV infusion.

CONCLUSIONS

The results of this study suggest that an IC adenosine continuous infusion method via a microcatheter is safe and effective in inducing steady-state hyperemia and more potent and quicker in inducing optimal hyperemia than the standard IV infusion method.

Effects of Intraaortic Balloon Pumping on the Angiographic No-Reflow Phenomenon After Percutaneous Coronary Intervention in Patients With Anterior Myocardial Infarction

BACKGROUND

The effects of intraaortic balloon pumping (IABP) are considered to be a reduction in myocardial oxygen demand because of systolic left ventricular unloading and an increase in coronary blood flow. Although the former effect has been consistently recognized, the latter effect remains controversial. The purpose of this study was to examine the effects of IABP on the angiographic no-reflow phenomenon.

METHODS AND RESULTS

The coronary flow velocity pattern of the left anterior descending artery (LAD) was assessed by transthoracic Doppler echocardiography during IABP counterpulsation, and the effects of IABP were compared between angiographic no-reflow and good reflow patients. The study group comprised 17 patients with anterior myocardial infarction who underwent percutaneous coronary intervention and IABP for typical clinical indications. Echocardiographic data were obtained during 2:1 balloon pumping after coronary angioplasty. In the good reflow group (n=9), IABP counterpulsation increased the mean diastolic flow velocity (MDFV) and peak diastolic flow velocity (PDFV) by 56 +/- 32% (p<0.001) and 48 +/- 27% (p<0.001), respectively. In contrast, in the no-reflow group (n=8), IABP only increased the MDFV and PDFV by 19 +/- 33% (p=0.24) and 6 +/- 12% (p=0.22), respectively. Diastolic deceleration time was smaller and the prevalence of systolic retrograde flow was greater in the no-reflow group than in the good reflow group, and IABP affected neither parameter.

CONCLUSIONS

IABP had limited effects on LAD flow velocity pattern in patients with the angiographic no-reflow phenomenon.