Intravenous regadenoson with aminophylline reversal is safe and equivalent to intravenous adenosine infusion for fractional flow reserve measurements

Feasibility and safety of regadenoson stress perfusion protocol in pediatric transplant patients under general anesthesia

BACKGROUND

Cardiovascular magnetic resonance with myocardial stress perfusion (stress CMR) is a non-invasive technique that offers an assessment of myocardial function, perfusion, and viability. Regadenoson is a selective cardiac adenosine A2 receptor agonist with fewer side effects than adenosine and a favorable safety profile in older pediatric heart transplant recipients (PHTR). There are limited studies evaluating the hemodynamic response of regadenoson in pediatric patients under general anesthesia (GA).

METHODS

We reviewed our experience with regadenoson stress CMR in PHTR under GA from 2020-2024 and compared to a non-GA group of PHTR who underwent regadenoson stress CMR from 2015-2022. Demographic and clinical data were recorded. Hemodynamic response and adverse events were reviewed. CMRs were reviewed for perfusion abnormalities and semi-quantitative analysis was performed using myocardial perfusion reserve index (MPRI).

RESULTS

Forty-six PHTR underwent 53 stress CMRs under GA over the study period (mean age 7.8 years; range 3-19 years). All patients received endotracheal intubation and sevoflurane and were monitored during and after regadenoson administration per institutional protocol. Heart rate (HR) prior to regadenoson administration was 84±12 beats/min with a peak of 109±14 beats/min and average mean blood pressure (BP) was 63±12 mmHg with a nadir of 45±8 mmHg. Transient hypotension was observed in 33 (77%) scans, which resolved with phenylephrine. There were no other adverse events. Phenylephrine was used in 48 CMRs (91%) for BP support at the discretion of anesthesia. Thirty-eight PHTR underwent 48 stress CMRs without sedation. CMRs were matched by time since transplant. The non-GA group was significantly older (mean age 15.8 years; p<0.001). GA patients had a larger percent decrease in mean BP compared to non-GA patients (27±17% vs 15±17%; p<0.001) with no difference in HR change. There were no significant differences in rates of qualitative perfusion defects, (11% vs 4%, p=0.18), late gadolinium enhancement or MPRI values between the two groups.

CONCLUSION

Regadenoson stress CMR is safe and feasible in PHTR under GA. While hypotension was frequently seen, it improved in all cases with phenylephrine. Semi-quantitative myocardial perfusion analysis by MPRI is feasible in these young patients, however further studies are needed to assess its clinical utility in this population.

Differences in coronary microcirculation measurements during regadenoson vs. adenosine - induced hyperemia

BACKGROUND

Little is known about the similarity of microcirculation assessment outcomes performed with regadenoson and adenosine. The aim of the current study was to compare coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) assessment using adenosine and regadenoson, and to evaluate predictors regarding the size of differences.

METHODS

44 patients were enrolled and diagnosed between 2021 and 2023. Fractional flow reserve (FFR), CFR and IMR were measured twice in the circumflex (Cx) (n = 8) or left anterior descending (LAD) (n = 36) artery: once with continuous infusion of adenosine (Adenocor 140 µg/kg/min) and 10 minutes later with regadenoson (Rapiscan 400 µg i.v.).

RESULTS

Averaged results were quantified with adenosine and regadenoson for FFR (0.81 [0.75 ÷ 0.89] vs. 0.80 [0.73 ÷ 0.88]), CFR (3.84 [1.67 ÷ 4.08] vs. 3.97 [1.78 ÷ 4.32]) and IMR (20.01 [11 ÷ 24.5] vs. 20.25 [10.75 ÷ 23]), respectively. None of the differences were statistically significant. Among the significant (p < 0.05) predictors of greater ΔCFR, the following can be noted: prior percutaneous transluminal angioplasty/carotid artery stenting (β = 2.35), oral anticoagulant usage (β = 0.89), and prior stroke/transient ischaemic attack (TIA) (β = 1.09), with the latter being also confirmed for greater ΔIMR (β = 8.89). Moreover, patients with New York Heart Association (NYHA) class II/III, as compared to those with NYHA class I, were more likely to have greater ΔIMR (β = 11.89).

CONCLUSIONS

Regadenoson may be a feasible alternative to adenosine in coronary microcirculation assessment, as it produces similar outcomes. Selected factors were found to be predictors of greater differences in IMR, CFR and FFR values according to the agent used for coronary hyperemia.

[Functional assessment of coronary stenosis: alternative hyperemic, nonhyperemic, and angiographic indexes]

Assessment of the functional significance of coronary artery stenoses to guide percutaneous coronary intervention is widely performed using pressure wire fractional flow reserve during adenosine- or adenosine triphosphate-induced hyperemia. However, the use of fractional flow reserve may be limited by the contraindications and adverse effects of this hyperemic stimulus, as well as the potential risk of vessel damage from the pressure wire. This review will discuss alternative evaluation methods, including various hyperemic agents, nonhyperemic pressure ratios, and angiography-based indices.

Comparative efficacy and safety of adenosine and regadenoson for assessment of fractional flow reserve: A systematic review and meta-analysis

BACKGROUND

Adenosine is a coronary hyperemic agent used to measure invasive fractional flow reserve (FFR) of intermediate severity coronary stenosis.

AIM

To compare FFR assessment using adenosine with an alternate hyperemic agent, regadenoson.

METHODS

PubMed, Google Scholar, CINAHL and Cochrane databases were queried for studies comparing adenosine and regadenoson for assessment of FFR. Data on FFR, correlation coefficient and adverse events from the selected studies were extracted and analyzed by means of random effects model. Two tailed P-value less than 0.05 was considered significant. Heterogeneity was assessed using I² test.

RESULTS

Five studies with 248 patients were included in the final analysis. All included patients and coronary lesions underwent FFR assessment using both adenosine and regadenoson. There was no significant mean difference between FFR measurement by the two agents [odds ratio (OR) = -0.00; 95% confidence interval (CI): (-0.02)-0.01, P = 0.88]. The cumulative correlation coefficient was 0.98 (0.96-0.99, P < 0.01). Three of five studies reported time to FFR with cumulative results favoring regadenoson (mean difference 34.31 s; 25.14-43.48 s, P < 0.01). Risk of adverse events was higher with adenosine compared to regadenoson (OR = 2.39; 95%CI: 1.22-4.67, P = 0.01), which most commonly included bradycardia and hypotension. Vast majority of the adverse events associated with both agents were transient.

CONCLUSION

The performance of regadenoson in inducing maximal hyperemia was comparable to that of adenosine. There was excellent correlation between the FFR measurements by both the agents. The use of adenosine, was however associated with higher risk of adverse events and longer time to FFR compared to regadenoson.

Safety and tolerability of regadenoson in comparison with adenosine stress cardiovascular magnetic resonance: Data from a multicentre prospective registry

To assess the feasibility and incidence of immediate complications of stress cardiovascular magnetic resonance (CMR) with regadenoson in comparison with adenosine in a large referral population. This is a large, multicenter, prospective registry of vasodilator stress-CMR in a referral population. We recorded the clinical and demographic data, quality of test, CMR findings, hemodynamic data, and complications. Between January 2016 and July 2019, 2908 patients underwent stress-CMR, 2253 with regadenoson and 655 with adenosine. 25.1% of patients had previously known coronary artery disease (CAD). In 305 patients regadenoson was used due to presence of chronic obstructive pulmonary disease (COPD) or asthma, while in 1948 subjects regadenoson was used as first-line vasodilator. Quality was optimal in 90.0%, suboptimal in 9.5%, and poor in 0.5%. Images were diagnostic in 98.9%. After stress with regadenoson, aminophylline 200 mg was administered intravenously in all patients. No patient died or had severe immediate complications with regadenoson as opposed to 2 severe bronchospasm with adenosine (p = 0.05). 11 patients (0.5%) had non-severe complications with regadenoson and five patients (0.8%) with adenosine (p = n.s.). Only two patients (0.088%) had non-severe bronchospasm after regadenoson administration. All complications were solved in the CMR unit, with no need for further specific care. Factors significantly associated with presence of complications were history of COPD or asthma and detection of inducible ischaemia. Patients had significantly more minor symptoms when adenosine was used (66.0% vs. 18.4%, p < 0.0001). Stress-CMR with regadenoson is feasible, providing diagnostic information in a referral population. Regadenoson had an excellent safety profile and better tolerability than adenosine, with no serious immediate complications and low incidence of non-severe complications. Only inducible ischaemia and previous history of COPD or asthma were associated with complications after regadenoson-CMR. The incidence of minor symptoms was low.

Intravenous regadenoson with aminophylline reversal is safe and equivalent to intravenous adenosine infusion for fractional flow reserve measurements

BACKGROUND

Small studies have shown that adenosine is equivalent to regadenoson when obtaining coronary fractional flow reserve (FFR) measurements. A study that also evaluates time and safety of aminophylline reversal of regadenoson effects has not been presented.

HYPOTHESIS

Reversal of regadenoson with aminophylline is safe and equivalent to adenosine for FFR measurements.

METHODS

Forty-six consecutive patients who underwent clinically indicated FFRs at the time of coronary angiography were enrolled between 4/2012 and 5/2014. Each patient had FFR measured using adenosine 140 mcg/kg/min IV, and following return to baseline, FFR was measured using regadenoson 400 mcg IV, which then was reversed with aminophylline 150 mg IV. Time to baseline hemodynamics was measured. Agreement between the two assessments was compared using linear regression.

RESULTS

FFR results were similar with both agents (R² = 0.935, P < 0.0001). Also, using the 0.80 cutoff for significantly depressed FFR, there was no divergence regarding studies' significance. After aminophylline reversal of regadenoson, hemodynamics returned to baseline in 111 ± 71 seconds. There were no unexpected side effects or complications.

CONCLUSIONS

For FFR measurement, regadenoson and adenosine are equivalent hyperemic agents. Regadenoson with aminophylline reversal may be considered as an alternative to adenosine for FFR measurements.