Lessons from regadenoson and low-level treadmill/regadenoson myocardial perfusion imaging: initial clinical experience in 1263 patients

Clinical experience with regadenoson SPECT myocardial perfusion imaging: insights into patient characteristics, safety, and impact of results on clinical management

The Henry Ford Hospital (HFH) regadenoson (REG) registry includes patients with a variety of comorbidities allowing for the evaluation of outcomes in a large, unselected population. Using a database of electronic medical records and nuclear cardiology reports, patients aged > 18 years who underwent REG-facilitated single-photon emission computed tomography (SPECT) testing at HFH between January 2009 and August 2012 were identified. The primary objective was to describe the clinical and demographic characteristics of patients who had undergone REG only vs REG WALK (REG + low-level exercise) SPECT. A total of 2104 patients were included in the analysis (mean age 65.3 years; 50% women; 51% African American, 43% Caucasian). For the REG only (n = 1318) and REG WALK (n = 786) cohorts, SPECT was abnormal in 37% of patients (REG only, 39%; REG WALK, 34%; P < 0.01). No differences in diagnostic modalities or interventions in 90 days after SPECT were observed. Immediate safety analysis showed no deaths 48 h after REG SPECT testing. Although they guide invasive therapy, abnormal scans do not automatically lead to invasive testing. This demonstrates the focus on initial medical management, which reflects the existing evidence of initial goal-directed medical management of stable coronary disease.

Modulation of Blood-Brain Barrier Permeability by Activating Adenosine A2 Receptors in Oncological Treatment

The blood–brain barrier (BBB) plays an important protective role in the central nervous system and maintains its homeostasis. It regulates transport into brain tissue and protects neurons against the toxic effects of substances circulating in the blood. However, in the case of neurological diseases or primary brain tumors, i.e., gliomas, the higher permeability of the blood-derived substances in the brain tissue is necessary. Currently applied methods of treatment for the primary brain neoplasms include surgical removal of the tumor, radiation therapy, and chemotherapy. Despite the abovementioned treatment methods, the prognosis of primary brain tumors remains bad. Moreover, chemotherapy options seem to be limited due to low drug penetration into the cancerous tissue. Modulation of the blood–brain barrier permeability may contribute to an increase in the concentration of the drug in the CNS and thus increase the effectiveness of therapy. Interestingly, endothelial cells in cerebral vessels are characterized by the presence of adenosine 2A receptors (A2AR). It has been shown that substances affecting these receptors regulate the permeability of the BBB. The mechanism of increasing the BBB permeability by A2AR agonists is the actin-cytoskeletal reorganization and acting on the tight junctions. In this case, the A2AR seems to be a promising therapy target. This article aims to assess the possibility of increasing the BBB permeability through A2AR agonists to increase the effectiveness of chemotherapy and to improve the results of cancer therapy.

Position paper on stress cardiac magnetic resonance imaging in chronic coronary syndrome: Endorsed by the Société française de radiologie (SFR), the Société française d'imagerie cardiovasculaire (SFICV) and the Société française de cardiologie (SFC)

This paper is intended to update the former consensus between the French Societies of Radiology and Cardiology about the use of stress cardiac magnetic resonance imaging in chronic coronary syndrome, published in 2009. The Delphi method was used to build the present consensus. This expert panel consensus includes recommendations for indications, the procedure (with patient preparation), stress-inducing drugs, the acquisition protocol, interpretation and risk stratification by stress magnetic resonance imaging.

Position paper on stress cardiac MRI in chronic coronary syndrome: Endorsed by the Société Française de Radiologie (SFR) the Société Française d'Imagerie CardioVasculaire (SFICV) and the Société Française de Cardiologie (SFC)

This position paper was intended to update the former consensus between the French Societies of Radiology and Cardiology about the use of stress cardiac magnetic resonance imaging (MRI) in chronic coronary syndrome published in 2009. The Delphi method was used to build the present consensus. This expert panel consensus includes recommendations for indications, procedure with patient preparation, stress inducing drugs, acquisition protocol, interpretation and risk stratification by stress MRI.

Trials and Tribulations of Assessing New Imaging Protocols: Combining Vasodilator Stress With Exercise

Among all patients referred for stress myocardial perfusion imaging (MPI), a substantial proportion in contemporary practice cannot exercise. Another group of patients are those who are thought to be able to achieve an adequate workload with treadmill (or bicycle) exercise but do not achieve at least 85% of maximum predicted heart rate without developing symptoms. There has been substantial interest and literature on the adjunctive use of vasodilator stress during the same visit to generate best-quality results for patients who do not exercise adequately. Current American Society of Nuclear Cardiology Guidelines recommend the possible use of vasodilator stress agents to supplement exercise in those patients who do not achieve target heart rate. However, optimal timing of administration is not clear. Herein, we summarize literature to date on the combination of vasodilator and exercise stress testing in light of the recently published Exercise to Regadenoson in Recovery Trial (EXERRT).

Incidence of atrioventricular block with vasodilator stress SPECT: A meta-analysis

BACKGROUND

Adenosine or regadenoson are often used with pharmacologic stress testing. Adenosine may trigger atrioventricular block (AVB). Despite its higher selectivity, regadenoson has also been associated with AVB. We studied the incidence of de novo AVB with these agents.

METHODS

A comprehensive search of SCOPUS was performed from inception to March 2016. Studies of at least 10 patients, using adenosine and/or regadenoson with SPECT-MPI, reporting rates of AVB were selected for further review.

RESULTS

Thirty four studies were pooled including 22,957 patients. Adenosine was used in 21 studies and regadenoson in 15. Both were administered in two studies. The estimated incidence of overall and high-grade AVB was 3.81% (95% CI 1.99%-6.19%) and 1.93% (95% CI 0.77%-3.59%), respectively. The incidence of AVB (8.58%; 95% CI 5.55%-12.21% vs 0.30%; 95% CI 0.04%-0.82%, respectively, P < .001) and high-grade AVB (5.21%; 95% CI 2.81%-8.30% vs 0.05%; 95% CI < .001%-0.19% respectively, P < .001) were higher with adenosine compared to regadenoson.

CONCLUSION

AVB is seen in about 4% of patients undergoing vasodilator stress test. Both overall and high-grade AVB are more frequent with adenosine compared to regadenoson.

Regadenoson use in chronic kidney disease and end-stage renal disease: A focused review

Regadenoson is a selective A2A adenosine receptor agonist that has been approved as a vasodilator stress agent with single-photon emission-computed tomography (SPECT) myocardial perfusion imaging (MPI). Since its approval by the Food and Drug Administration (FDA) in 2008, it has become the most commonly used pharmacologic stress agent with SPECT-MPI. Given that it is predominantly renally excreted, its use in patients with chronic kidney disease has been the subject of active post-marketing clinical research. Until recently, prescribing information regarding the use of regadenoson in patients with end-stage renal disease (ESRD) was not defined in the package insert. Based on accumulating data since its initial approval, the FDA has recently outlined the use of regadenoson in patients with ESRD in a label update on January 17, 2017. In this review, we discuss the evidence leading to the recent label update, focusing on the pharmacokinetics of regadenoson in patients with impaired kidney function, the safety and tolerability of regadenoson in patients with chronic kidney disease and ESRD, and the prognostic value of regadenoson stress MPI in this patient population.

Prognostic value of vasodilator response using rubidium-82 positron emission tomography myocardial perfusion imaging in patients with coronary artery disease

BACKGROUND

Prognostic value of positron emission tomography (PET) myocardial perfusion imaging (MPI) is well established. There is paucity of data on how the prognostic value of PET relates to the hemodynamic response to vasodilator stress. We hypothesize that inadequate hemodynamic response will affect the prognostic value of PET MPI.

METHODS AND RESULTS

Using a multicenter rubidium (Rb)-82 PET registry, 3406 patients who underwent a clinically indicated rest/stress PET MPI with a vasodilator agent were analyzed. Patients were categorized as, "responders" [increase in heart rate ≥ 10 beats per minute (bpm) and decrease in systolic blood pressure (SBP) ≥10 mmHg], "partial responders" (either a change in HR or SBP), and "non-responders" (no change in HR or SBP). Primary outcome was all-cause death (ACD), and secondary outcome was cardiac death (CD). Ischemic burden was measured using summed stress score (SSS) and % left ventricular (LV) ischemia. After a median follow-up of 1.68 years (interquartile range = 1.17- 2.55), there were 7.9% (n = 270) ACD and 2.6% (n = 54) CD. Responders with a normal PET MPI had an annualized event rate (AER) of 1.22% (SSS of 0-3) and 1.58% (% LV ischemia = 0). Partial and non-responders had higher AER with worsening levels of ischemic burden. In the presence of severe SSS ≥12 and LV ischemia of ≥10%, partial responders had an AER of 10.79% and 10.36%, compared to non-responders with an AER of 19.4% and 12.43%, respectively. Patient classification was improved when SSS was added to a model containing clinical variables (NRI: 42%, p < 0.001) and responder category was added (NRI: 61%, p < 0.001). The model including clinical variables, SSS and hemodynamic response has good discrimination ability (Harrell C statistics: 0.77 [0.74-0.80]).

CONCLUSION

Hemodynamic response during a vasodilator Rb-82 PET MPI is predictive of ACD. Partial and non-responders may require additional risk stratification leading to altered patient management.

The EXERRT trial: "EXErcise to Regadenoson in Recovery Trial": A phase 3b, open-label, parallel group, randomized, multicenter study to assess regadenoson administration following an inadequate exercise stress test as compared to regadenoson without exercise for myocardial perfusion imaging using a SPECT protocol

BACKGROUND

This study assessed the non-inferiority and safety of regadenoson administration during recovery from inadequate exercise compared with administration without exercise.

METHODS

Patients unable to achieve adequate exercise stress were randomized to regadenoson 0.4 mg either during recovery (Ex-Reg) or 1 hour after inadequate exercise (Regadenoson) (MPI1). All patients also underwent non-exercise regadenoson MPI 1-14 days later (MPI2). The number of segments with reversible perfusion defects (RPDs) detected using single photon emission computerized tomography imaging was categorized. The primary analysis evaluated the majority agreement rate between Ex-Reg and Regadenoson groups.

RESULTS

1,147 patients were randomized. The lower bound of the 95% confidence interval of the difference in agreement rates (-6%) was above the -7.5% non-inferiority margin, demonstrating non-inferiority of Ex-Reg to Regadenoson. Adverse events were numerically less with Ex-Reg (MPI1). In the Ex-Reg group, one patient developed an acute coronary syndrome and another had a myocardial infarction following regadenoson after exercise. Upon review, both had electrocardiographic changes consistent with ischemia prior to regadenoson.

CONCLUSIONS

Administering regadenoson during recovery from inadequate exercise results in comparable categorization of segments with RPDs and with careful monitoring appears to be well tolerated in patients without signs/symptoms of ischemia during exercise and recovery.

Influence of body mass index and type of low-level exercise on the side effect profile of regadenoson

PURPOSE

Regadenoson, an A_2A adenosine receptor pharmacologic stress agent for radionuclide myocardial perfusion imaging (MPI), is administered as a single, fixed dose. We studied the side effect profile of regadenoson combined with two types of low-level exercise, according to body mass index (BMI).

METHODS

Three hundred and fifty-six patients (46.1% men, mean age 67.7±10.7 years, range 31-90 years) underwent regadenoson stress testing combined with low-level exercise. Subjects were classified according to BMI as normal, overweight, or obese, and the type of low-level exercise performed as walking on the treadmill (TE group, n=190) or forcefully swinging legs while sitting (SS group, n=166). Patients' demographics, medical history, clinical symptoms during stress, changes in ECG, oxygen saturation (SatO₂), systolic blood pressure (SBP), and heart rate (HR) were evaluated.

RESULTS

Groups were comparable (p=ns) with regard to cardiovascular risks factors. The incidence of side effects was similar across BMI (p=ns), although the TE patients showed improved profiles over those with SS exercise, with a significantly lower incidence of flushing, dizziness and nausea/gastrointestinal discomfort (12.9% vs. 28.4%; 19.9% vs. 33.4%; 11.4% vs. 19.2%, respectively; all p<0.05). Regarding the hemodynamic response, we did not observe significant changes in SBP and HR after regadenoson administration across BMI categories. Comparing the TE and SS groups, no significant changes were observed in SBP, but there was a higher increase in HR in the TE group (p<0.05).

CONCLUSIONS

Regadenoson in combination with low-level exercise is safe and well tolerated over a wide range of BMI, with TE exercise showing a better side effect profile than SS.

Myocardial CT perfusion imaging for ischemia detection

Coronary computed tomography angiography (CCTA) plays an important role in many specific scenarios such as in symptomatic patients with intermediate pretest of coronary artery disease (CAD), as well as in the triage of patients with acute chest pain with TIMI risk ≤2. However, it cannot detect the presence of associated ischemia, which is critical for clinical decision making among patients with moderate to severe stenosis. Although functional information can be obtained with different non-invasive tools, cardiac CT is the unique modality that can perform a comprehensive evaluation of coronary anatomy plus the functional significance of lesions. Myocardial CT perfusion (CTP) can be performed with different approaches such as static and dynamic CTP. In addition, static CTP can be performed using single energy CT (SECT) or dual energy CT (DECT). In this review, we will discuss the technical parameters and the available clinical evidence of static CTP using both SECT and DECT.

A useful and easy to develop combined stress test for myocardial perfusion imaging: Regadenoson and isometric exercise, preliminary results

BACKGROUND

Regadenoson, a selective A2a receptor agonist, is a vasodilator increasingly used in myocardial perfusion imaging. Adjunction of isometric exercise is a simple method that could improve side effect profile while providing better image quality.

METHODS

Patients undergoing SPECT MPI were prospectively enrolled in handgrip-Regadenoson (HG-Reg test, N = 20) and Regadenoson (Reg) stress test (N = 40). Investigator blinded to stress test analyzed clinical data and images.

RESULTS

Heart rate (HR) increase was statistically higher in the HG-Reg group (27 vs 22 bpm, P = .019). Decrease in SBP was less frequent in the HG-Reg group than in the Reg group (55% vs 85.5%, P = .005), there were less drops >10 mmHg (45% vs 77.7%, P = .012). During stress testing, fewer subjects reported at least one side effect in the HG-Reg compared to Reg group (70% vs 92.5%, P = .021). Images were more often classified as good in the HG-Reg group (75% vs 52.5% in the Reg group, P = .25).

CONCLUSIONS

Adjunction of handgrip exercise to Regadenoson administration is a well-tolerated and easy method, without loss of time. Furthermore, image quality seems to be better.

Safety of regadenoson in patients with severe chronic obstructive pulmonary disease

OBJECTIVE

To assess the safety of regadenoson, a selective agonist of A2A adenosine receptors, combined with low-level exercise in subjects with severe chronic obstructive pulmonary disease (COPD), referred for myocardial perfusion imaging (MPI).

METHODS

We studied prospectively 12 male patients with severe COPD. Stress was 4min of low-level exercise with bolus injection of regadenoson (0.4mg) at 1.5min, followed by (99m)Tc-MPI agent injection. Demographics, medical history, lung medications, adverse events, oxygen saturation (SatO2), MPI findings for coronary artery disease (CAD), and changes in systolic blood pressure (SBP), and heart rate (HR) were registered.

RESULTS

The observed adverse event profile of regadenoson was similar to that of patients with mild-moderate COPD. There was no clinical exacerbation of COPD. Adverse events were self-limiting: dyspnea (33.3%), fatigue (25.0%), chest pain, headache (16.7%, respectively), and gastrointestinal discomfort, dry mouth, flushing, feeling hot and dizziness (8.3%, respectively). 25.0% of patients did not report any symptoms. We observed significant increases in SBP and HR from baseline (142.6mmHg±22.3 vs 152.5mmHg±18.5, and 80 b.p.m.±18 vs 105 b.p.m.±22, respectively; p<0.05).

CONCLUSIONS

Regadenoson combined with low-level exercise is safe and well tolerated in stable patients with severe COPD undergoing MPI.

[Regadenoson as a new stress agent in myocardial perfusion imaging. Initial experience in The Netherlands]

OBJECTIVE

Regadenoson is a recently approved selective adenosine-2A receptor agonist to induce pharmacological stress in myocardial perfusion imaging (MPI) procedures using a single bolus injection.

MATERIAL AND METHODS

We included 123 patients referred for MPI because of suspected coronary arterial disease (CAD). Of these, 66 patients underwent a regadenoson stress test and 57 patients underwent an adenosine stress test preceding standard myocardial SPECT imaging. Technicians, physicians and patients were asked to report their experience using questionnaires.

RESULTS

As compared to adenosine, regadenoson did not produce any atrio-ventricular block (0 vs. 10% with adenosine), but did produce minor tachycardia and minimal blood pressure changes while all other side effects were milder and shorter. There were fewer patients with severe complaints after taking regadenoson than adenosine (17% vs. 32%, respectively, p<0.01). The most frequent complaint reported was dyspnea, followed by flushing and chest pain. However, when they did occur, they usually disappeared rapidly. The overall symptom score, including severity and duration of side effects, was significantly lower after regadenoson than after adenosine (6.7±6.3 vs. 10.0±7.9, respectively; p<0.01.) SPECT imaging results were similar. The regadenoson procedure was faster and more practical.

CONCLUSION

Regadenoson, the new selective adenosine-2A receptor agonist, is a stress agent for MPI with a patient- and department friendly profile.

Regadenoson use in patients with chronic obstructive pulmonary disease: the state of current knowledge

Stress testing is challenging in patients with chronic obstructive pulmonary disease (COPD). Functional capacity is generally decreased in this patient population, limiting patients’ ability to achieve physiologic stress through exercise. Additionally, due to emphysematous changes, COPD patients tend to have poor acoustic windows that impair the quality and therefore diagnostic accuracy of stress echocardiography techniques. Pharmacologic stress myocardial perfusion imaging (MPI) testing is also problematic, particularly due to the concern for adenosine-induced bronchoconstriction with conventional vasodilator stress agents. Regadenoson, a selective A_2A adenosine receptor agonist, has gained popularity due to its ease of administration and improved patient experience in the general population. The literature describing the experience with regadenoson in COPD patients, though limited, is rapidly growing and reassuring. This review summarizes the pharmacology and clinical application of this novel stress agent and presents the available data on the safety and tolerability of its use in COPD patients.

Comparative study of the safety of regadenoson between patients with mild/moderate chronic obstructive pulmonary disease and asthma

PURPOSE

To compare the safety of regadenoson, a selective agonist of A2A adenosine receptors, combined with low-level exercise, between subjects with mild/moderate chronic obstructive pulmonary disease (COPD) and asthma referred for myocardial perfusion imaging (MPI).

METHODS

We studied 116 patients, of whom 67 had COPD and 49 asthma (62 % men, mean age 68.3 ± 11.3 years, range 31 - 87 years). Patient demographics, past medical history, medications, clinical symptoms during stress and changes in blood pressure (BP) and heart rate (HR) were evaluated.

RESULTS

Both groups were comparable with regard to hypertension, dyslipidaemia, diabetes and medications with the exception of a higher rate of use of anticholinergics in patients with COPD and of antileukotrienes in asthmatics (58.2 % vs. 28.6 % and 1.5 % vs. 14.3 %, respectively; all p < 0.01). There was a higher incidence of dyspnoea in COPD patients and of headache and feeling hot in asthmatic patients (40.3 % vs. 22.4 %, 6 % vs. 18.4 % and 10.4 % vs. 26.5 %, respectively; all p < 0.05). Although there was no difference in the incidence of other adverse events, we observed a higher frequency in asthmatics of flushing, dry mouth, sweating and fatigue (1.5 % vs. 6.1 %, 14.9 % vs. 24.5 %, 0 % vs. 4.1 % and 37.3 % vs. 49 %, respectively). Adverse events were self-limiting, except in three patients who suffered persistent dyspnoea (2 of 67 COPD patients; 1 of 49 asthma patients) requiring theophylline administration. We observed no significant changes in BP among either group, but there was a tendency towards a higher increase in systolic BP in COPD patients following regadenoson administration (148.3 ± 27.6 vs. 154.6 ± 31.0 mmHg, p = 0.056).

CONCLUSION

This study showed a good safety profile in our series of COPD and asthma patients undergoing MPI. Regadenoson was well tolerated by all patients, with dyspnoea, headache and feeling hot showing differences between groups.

Comparison of hemodynamic and stress testing variables in patients undergoing regadenoson stress myocardial perfusion imaging to regadenoson with adjunctive low-level exercise myocardial perfusion imaging

BACKGROUND

Regadenoson (REG), a selective adenosine A2a receptor agonist, is becoming the preferred pharmacologic agent for stress myocardial perfusion imaging (MPI). Hemodynamic and stress variables, immediate safety and use of aminophylline when using REG combined with low-level exercise (REG WALK MPI) compared with REG MPI, have not been well studied and formed the basis of our study.

METHODS

Retrospective evaluation of patients who underwent REG MPI (n = 887) was compared to patients undergoing REG WALK MPI (n = 485) from January to November 2009. Patient demographics, hemodynamic parameters, REG MPI data, side effects, immediate major clinical events, and use of aminophylline were evaluated.

RESULTS

Patients in REG WALK MPI group tended to be younger, male and obese compared to patients in REG MPI group. REG WALK MPI patients had higher stress heart rate (103 ± 20.5 vs 84 ± 19 bpm, P = .001), higher heart rate reserve (36.3 ± 19 vs 14.7 ± 15.5 bpm, P < .001), and greater systolic blood pressure rise (4.8 ± 21.3 vs -8.9 ± 19.8 mm Hg, P < .001), compared to REG MPI patients. No major adverse events were reported immediately after REG WALK MPI. There were no differences in drug-related side effects in between the two groups; however, the use of aminophylline was lower in REG WALK MPI Group (5.6% vs 11.4%, P = .001).

CONCLUSION

REG WALK MPI gives more favorable hemodynamic response with lesser use of aminophylline and no increase in adverse events when compared with REG MPI.

Regadenoson: review of its established role in myocardial perfusion imaging and emerging applications

Myocardial perfusion imaging is a well-established noninvasive modality for the diagnosis and prognosis of coronary artery disease. The pharmacologic stress agents adenosine and dipyridamole are widely used in imaging studies, but cause undesirable side effects, like atrioventricular block and bronchospasm, due to their nonselective adenosine receptor activation. Furthermore, the mode of administration of these agents as a bolus infusion is less preferred. Regadenoson, an A2A adenosine receptor selective pharmacologic stress agent was approved in 2008 and is widely used instead of adenosine and dipyridamole. This article reviews regadenosons structure, mechanism of action, advantages over adenosine and dipyridamole, and its role in various patient populations undergoing stress perfusion imaging. Emerging applications where regadenoson could be of potential use are also explored.

A strategy of symptom-limited exercise with regadenoson-as-needed for stress myocardial perfusion imaging: a randomized controlled trial

BACKGROUND

Ambulatory patients with uncertain functional capacity may benefit from combined exercise and vasodilator stress protocols for myocardial perfusion imaging (MPI). The safety and MPI image quality with regadenoson administered during symptom-limited exercise have not been prospectively evaluated.

METHODS AND RESULTS

A total of 140 patients (mean age 61 years, 48% female) referred for exercise with vasodilator stress MPI were randomized 2:1 to a strategy of exercise with regadenoson-as-necessary (Ex-Reg, n = 96) or dipyridamole with exercise (Dip-Ex, n = 44) after Duke Activity Status Index (DASI) scoring (median score 28 vs 24, P = .09). Ex-Reg subjects commenced treadmill exercise and regadenoson was administered only if the subject was unable to reach standard endpoints. Dip-Ex subjects received dipyridamole prior to symptom-limited exercise. Hemodynamics were recorded throughout. Subjects completed symptom questionnaires and MPI image quality was assessed by blinded read. Ex-Reg subjects were more likely to achieve ≥85% age-predicted maximum heart rate than Dip-Ex subjects (57% vs 32%, P < .01). Only 50% of subjects meeting inclusion criteria and randomized to Ex-Reg required regadenoson and none had symptomatic hemodynamic changes. Severe side effects or adverse events occurred in 16% of Ex-Reg and 24% of Dip-Ex subjects (P = .12). MPI image quality was "good" or "excellent" in 88% of Ex-Reg subjects and 86% of Dip-Ex subjects (P = .33).

CONCLUSION

A strategy of exercise with regadenoson-as-needed for MPI offers similar safety and side effect profile with similar image quality compared to dipyridamole with exercise, with reduced pharmaceutical use.

Regadenoson: a focused update

Since its approval by the Food and Drug Administration in 2008, regadenoson has become the most commonly used vasodilator in the United States. Previous reviews have summarized the pre-clinical and clinical data on the use of regadenoson for myocardial perfusion imaging (MPI). Since then, data have emerged on the safety of this agent in special groups of patients such as those with chronic kidney disease, airway disease (asthma and chronic obstructive pulmonary disease), and liver disease. There has also been recent interest in the use of regadenoson in hybrid protocols with exercise as a way to improve patient tolerance and image quality. Finally, although regadenoson was approved for clinical use based on the agreement rate of regadenoson MPI and adenosine MPI with regards to perfusion abnormalities, data are now available on the prognostic data derived from regadenoson MPI. We will briefly summarize these recent reports here in a focused update on the use of regadenoson for MPI.

Regadenoson pharmacologic stress for myocardial perfusion imaging: a three-way comparison between regadenoson administered at peak exercise, during walk recovery, or no-exercise

BACKGROUND

Regadenoson (Reg) is being administered with increasing frequency either at peak exercise (ExPeak-Reg) or during a slow-down/walking recovery state (ExRec-Reg) rather than at rest (Rest-Reg). The aim of this study was to compare the clinical response of ExPeak-Reg, ExRec-Reg, and Rest-Reg.

METHODS

We compared 531 patients divided equally between Rest-Reg, ExPeak-Reg, and ExRec-Reg matched for age, sex, and BMI.

RESULTS

The average systolic blood pressure (SBP) rise following Reg was modest, but there was considerable heterogeneity and the ExPeak-Reg group had a higher percentage of patients who had a SBP rise of 40 mm Hg or a fall of 20 mm Hg than either the ExRec-Reg or the Rest-Reg groups (≥40 mm Hg rise 6.8%, 1.7%, and 1.7%, respectively) (P < .02) (≥20 mm Hg fall 15.8%, 13.0%, and 7.3%, respectively) (P < .05). Chest discomfort, nausea, dizziness, and interfering abdominal radiotracer activity were less common in both exercise Reg groups compared to Rest-Reg (P < .05).

CONCLUSION

Regadenoson injected at peak of symptom-limited exercise was generally well tolerated, but some patients had a significant rise or drop in SBP. There is no apparent advantage of administering regadenoson at peak exercise rather than during walk recovery, and the latter approach may have a greater safety margin.

Safety and tolerability of regadenoson in 514 SPECT MPI patients with and without coronary artery disease and submaximal exercise heart rate response

PURPOSE

The safety of regadenoson (Reg) during low-level exercise testing has been established. However, its administration at peak exercise for patients who do not reach target heart rate (THR) on standard exercise treadmill stress testing (ETT) needs to be established, particularly among patients with known coronary artery disease (CAD) METHODS: From our stress myocardial perfusion imaging (MPI) database, we identified all patients between 2009 and 2012 who underwent standard ETT and received Reg at peak exercise for failure to reach THR. Hemodynamics, side effects, and adverse events were entered prospectively into the database at the time of testing and were subsequently retrieved for analysis.

RESULTS

There were 514 patients, mean age 60 ± 12 years, 34 % female gender, and 51 % with prior CAD. There were 218 (42 %) and 297 (57 %) patients who underwent standard or modified Bruce and Cornell protocols, respectively, and with a mean exercise time of 5.8 ± 2.1 min. The mean percentage of peak heart rate achieved was 71 ± 8 %, and mean maximal metabolic equivalent (MET) was 6.7 ± 1.8. There were 63 (12 %) patients who developed ≥30 mmHg drop in systolic blood pressure (SBP) after 2 min of Reg administration, and 10 (2 %) had SBP <100 mmHg at 2 min and were younger and achieved higher METs; 8 and 2 patients were symptomatic, respectively. The most common side effects reported were shortness of breath (12 %), chest pain/discomfort (13 %), and dizziness (7 %). There was one syncopal event, but no high-degree heart block, cardiac or respiratory arrest. Four patients received aminophylline. Women were more likely to have shortness of breath or gastrointestinal symptoms, while diabetics were less likely to have chest discomfort. There was otherwise no significant difference in adverse events between different groups including those with and without CAD.

CONCLUSION

Among patients undergoing standard treadmill stress testing for MPI who do not reach THR, the administration of Reg at peak exercise is safe and without major adverse events. Future large prospective studies are warranted to further evaluate the off-label use of Reg in this setting.

Safety and feasibility of regadenoson use for suboptimal heart rate response during symptom-limited standard Bruce exercise stress test

BACKGROUND

Regadenoson during exercise stress test (ETT) can provide maximal hyperemia for myocardial perfusion imaging (MPI), along with exercise information. Our aim was to study the feasibility and safety of regadenoson injection at peak ETT for submaximal heart rate (HR) response.

METHODS

Consecutive patients who underwent SPECT MPI with standard Bruce ETT or supine-regadenoson (Supine-Reg) were analyzed. ETT patients were grouped as ETT-Max [maximal HR > 0.85 * (220 - age), N = 1,522], ETT-Submax (submaximal HR no regadenoson, N = 504), ETT-Reg (submaximal HR and regadenoson, N = 211).

RESULTS

The HR during ETT was submaximal in 715 (32%) patients. Of these, 211 patients (30%) underwent ETT-Reg (mean exercise duration: 5.5 ± 2.5 minutes). ETT-Reg patients had a higher frequency of hypertension, diabetes, smoking and beta-blocker use, similar rest systolic blood pressure (SBP), but lower rest and peak HR and peak SBP compared to ETT-Max patients. There were no serious complications with regadenoson. Side effects (49% vs 6%, P < .0001) were fewer and aminophylline use was lower with ETT-Reg compared to Supine-Reg (0.5% vs 8.1%, P = .001).

CONCLUSIONS

Submaximal HR response to ETT is common. ETT-Reg is safe, feasible, and well-tolerated. ETT-Reg facilitates a diagnostic MPI with reporting of functional capacity, exercise ECG/hemodynamic changes and MPI at maximal hyperemia.

Selective adenosine agonists and myocardial perfusion imaging

Selective adenosine receptor agonists have several advantages for use as stress agents in conjunction with myocardial perfusion imaging compared to the non selective agents such as adenosine and dipyridamole. This review will summarize the pre-clinical and clinical data on the selective adenosine agonist stress agents regadenoson (Lexiscan(®)), binodenoson (CorVue™) and apadenoson (Stedivaze™) that have been studied so far with focus on regadenoson that has the most clinical data published so far. The article will review the adenosine receptor types and properties. It will also review the various attributes of the selective adenosine agonists including their pharmacology, pharmacokinetics and pharmacodynamics, their coronary vasodilatory and hemodynamic effects, their safety and side effects, their interactions with other drugs and their use with myocardial perfusion imaging. The landmark trials of the selective adenosine agonists will be reviewed as well as their use in special patient populations undergoing stress myocardial perfusion imaging.

[State of the art: new developments in cardiac imaging]

Cardiac imaging continues to reveal new anatomical and functional insights into heart disease. In echocardiography, both transesophageal and transthoracic three-dimensional imaging have been fully developed and optimized, and the value of the techniques that have increased our understanding of cardiac mechanics and ventricular function is well established. At the same time, the healthcare industry has released new devices onto the market which, although they are easier to use, have limitations that restrict their use for routine assessment. Tomography's diagnostic and prognostic value in coronary artery disease continues to increase while radiation exposure becomes progressively lower. With cardiac magnetic resonance imaging, myocardial injury and recovery in ischemic heart disease and following acute coronary syndrome can be monitored in exquisite detail. The emergence of new combined tomographic and gamma camera techniques, exclusively developed for nuclear cardiology, have improved the quality of investigations and reduced radiation exposure. The hybrid or fusion images produced by combining different techniques, such as nuclear cardiology techniques and tomography, promise an exciting future.

MRI and CT in the diagnosis of coronary artery disease: indications and applications

In recent years, technical advances and improvements in cardiac computed tomography (CT) and cardiac magnetic resonance imaging (MRI) have provoked increasing interest in the potential clinical role of these techniques in the non-invasive work-up of patients with suspected coronary artery disease (CAD) and correct patient selection for these emerging imaging techniques. In the primary detection or exclusion of significant CAD, e.g. in the patient with unspecific thoracic complaints, and also in patients with known CAD or advanced stages of CAD, both CT and MRI yield specific advantages. In this review, the major aspects of non-invasive MR and CT imaging in the diagnosis of CAD will be discussed. The first part describes the clinical value of contrast-enhanced non-invasive CT coronary angiography (CTCA), including the diagnostic accuracy of CTCA for the exclusion or detection of significant CAD with coronary artery stenoses that may require angioplastic intervention, as well as potentially valuable information on the coronary artery vessel wall. In the second section, the potential of CT for the imaging of myocardial viability and perfusion will be highlighted. In the third and final part, the range of applications of cardiac MRI in CAD patients will be outlined.