Hemodynamic response, arrhythmic risk, and overall safety of regadenoson as a pharmacologic stress agent for myocardial perfusion imaging in chronic obstructive pulmonary disease and bronchial asthma patients

Regadenoson versus dipyridamole: Evaluation of stress myocardial blood flow response on a CZT-SPECT camera

BACKGROUND

Regadenoson is a selective adenosine receptor agonist. It is currently unclear if the level of hyperemia differs between stress agents. We compared Myocardial Blood Flow (MBF) and Myocardial Flow Reserve (MFR) response on CZT-SPECT Myocardial Perfusion Imaging (MPI) to evaluate if dipyridamole and regadenoson could induce the same level of hyperemia.

METHODS

228 patients with dynamic CZT-SPECT MPI were retrospectively analyzed (66 patients stressed with regadenoson and 162 with dipyridamole) in terms of MBF and MFR. To rule out confounding factors, two groups of 41 patients were matched for clinical characteristics in a sub-analysis, excluding high cardiovascular risk patients.

RESULTS

Overall stress MBF was higher in regadenoson patients (1.71 ± 0.73 vs. 1.44 ± 0.55 mL·min-1·g-1 for regadenoson and dipyridamole, respectively, p < .05). However, when confounding factors were ruled out, stress MBF (1.57 ± 0.56 vs. 1.61 ± 0.62 mL·min-1·g-1 for dipyridamole and regadenoson, respectively, p = .88) and MFR (2.62 ± 0.77 vs. 2.46 ± 0.76 for dipyridamole and regadenoson, respectively, p = .40) were not different between regadenoson and dipyridamole.

CONCLUSIONS

Our results suggest that dipyridamole and regadenoson induce equivalent hyperemia in dynamic SPECT with similar stress MBF and MFR in comparable patients.

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.

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.

Regadenoson myocardial perfusion scintigraphy for the evaluation of coronary artery disease in patients with lung disease: A series of five cases

Coronary artery disease (CAD) is a leading cause of death and morbidity globally. Myocardial perfusion scintigraphy (MPS) is commonly used for the diagnosis of CAD, necessitating hyperaemia achieved either by physical exertion or by pharmacological stress, most commonly through use of a coronary arteriolar dilator. This is challenging in patients with respiratory conditions because exercise may be submaximal and adenosine is contraindicated because of the risk of bronchoconstriction. Regadenoson is the only selective adenosine A2A receptor agonist approved as a vasodilator in MPS. The risk of bronchospasm with regadenoson has been investigated in large, randomised trials; however, patients with the most severe respiratory conditions were not included. In this case series, we present the use of regadenoson MPS in five patients with moderate-to-severe lung conditions, including patients requiring lung volume reduction surgery and lung transplant. In all cases, regadenoson MPS provided valuable information for risk assessment and treatment optimisation. Although dyspnoea occurred in all patients, regadenoson was well tolerated without serious adverse events or bronchospasm; in no case was intervention required to treat dyspnoea.

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.

Safety of regadenoson stress testing in patients with pulmonary hypertension

OBJECTIVES

We sought to determine the safety of regadenoson stress testing in patients with PH.

BACKGROUND

PH is increasingly recognized at more advanced ages. As many as one-third of patients with PH have coronary artery disease. Because of their physical limitations, patients with PH are unable to adequately exercise. Regadenoson can potentially have an adverse impact due to their tenuous hemodynamics. Current guidelines suggest performing a coronary angiography in patients with PH who have angina or multiple coronary risk factors.

METHODS

We identified 67 consecutive patients with confirmed PH by catheterization (mean PA > 25 mmHg not due to left heart disease) who underwent MPI with regadenoson stress. Medical records were reviewed to determine hemodynamic and ECG response to regadenoson.

RESULTS

No serious events occurred. Common side effects related to regadenoson were observed, dyspnea being the most common (70.6%). No syncope occurred. Heart rate increased from 74.6 ± 14 to 96.3 ± 18.3 bpm, systolic blood pressure increased from 129.8 ± 20.9 to 131.8 ± 31 mmHg, and diastolic blood pressure decreased from 77.1 ± 11.4 to 72.9 ± 15.3 mmHg. There was no ventricular tachycardia, ventricular fibrillation, or second- or third-degree atrioventricular block.

CONCLUSION

Regadenoson stress MPI appears to be well tolerated and safe in patients with PH.

Regadenoson in Myocardial Perfusion Study - First Institutional Experiences in Bosnia and Herzegovina

Introduction:

Myocardial perfusion imaging (MPI) is widely used in the evaluation of known and suspected coronary artery disease (CAD). Imaging of heart in stress and rest enables the comparison of myocardial uptake of radiotracer in proportion to the needs and coronary flow, which is used for detection of perfusion defects. Exercise stress and pharmacologic agents are used for the stressing purpose. Novel pharmacologic stressor regadenoson is A2A selective adenosine agonist, which selectively binds to the adenosine receptors in coronary arteries causing coronary dilatation.

Materials and methods:

We analyzed 50 myocardial perfusion studies performed with regadenoson as a pharmacologic agent that was injected before Tc99m-sestamibi in stress imaging. Stress and rest sets of images were evaluated for relative uptake of Tc99m-sestamibi in order to detect and characterize perfusion defects. After the injection of regadenoson, hemodynamic parameters and potential side-effects were closely monitored. Side-effects were stratified per severity as mild, moderate and severe. Studies were read by nuclear medicine physicians using quantitative perfusion SPECT software. Additional diagnostic information such as wall motion and wall thickening were provided by gating.

Results:

Thirty-three patients (66%) experienced one or more side-effects upon the administration of regadenoson, most commonly warmth and chest discomfort. In all patients but one (98%), the symptoms were mild, of short duration and self-limiting. Out of all side-effects registered, 44 (96%) were mild, and 2 (4%) were moderate. Two moderate side-effects developed in one patient with a prior history of asthma, and included shortness of breath and cough. Heart rate changed by 16 +- 31 bpm. Highest increase in blood pressure was 30 mm Hg for systolic, and 10 mm Hg for diastolic. One case of significant decrease in blood pressure was noted from the hypertensive basal values, 50 mm for systolic, and 30 mm Hg for diastolic. ST segment depression of up to 1 mm occurred in 4 cases (8%), and T-wave changes in 3 cases (6%). No conduction abnormalities, significant hypotension, symptomatic bradycardia or cardiac arrest ocurred.

Conclusion:

Our first institutional experiences proved regadenoson as A2A selective adenosine agonist as a pharmacologic stressor to be safe, tolerable and easily used. Its safety profile enabled the study to be performed in patients with respiratory disease also.

Regadenoson stress for myocardial perfusion imaging

Noninvasive functional imaging plays a major role in the diagnosis of hemodynamically significant coronary artery disease (CAD) by means of the detection of abnormal myocardial perfusion. For this, cardiac stressors are essential as they induce hypoperfusion in the presence of flow-limiting coronary stenosis. Several pharmacological stressors are currently available and it is important that clinicians who are involved in the care and management of patients with CAD become familiar with their indications, contraindications and protocols. Among the primary coronary vasodilator agents, regadenoson is increasingly used as the default stressor or as an alternative to other modalities of stress. This article provides an updated review of regadenoson stress for the assessment of patients with suspected or known CAD and describes its pharmacological properties, stress protocol, efficacy and safety profile.

[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.

Safety and tolerability of regadenoson CMR

AIMS

Knowledge of adverse events associated with regadenoson perfusion cardiac magnetic resonance (CMR) and patient tolerability has implications for patient safety and staff training. We sought to assess the safety and tolerability of regadenoson stress CMR.

MATERIALS AND METHODS

A group of 728 consecutive patients (median age 58, 44% female) and 25 normal volunteers (median age 21, 24% female) were recruited from August 2009 to March 2012 using a prospective, cross-sectional study design. Subjects were stressed using fixed-dose regadenoson and imaged using a 1.5T MRI scanner. Symptoms and adverse events including death, myocardial infarction (MI), ventricular tachycardia (VT)/ventricular fibrillation (VF), hospitalization, arrhythmias, and haemodynamic stability were assessed.

RESULTS

There were no occurrences of death, MI, VT/VF, high-grade atrioventricular block, or stress-induced atrial fibrillation. Notable adverse events included one case of bronchospasm and one case of heart failure exacerbation resulting in hospitalization. The most common symptoms in patients were dyspnoea (30%, n = 217), chest discomfort (27%, n = 200), and headache (15%, n = 111). There was minimal change between baseline and peak systolic and diastolic blood pressure in both patients and volunteers (P > 0.05). A blunted heart rate response to regadenoson was noted in patients with body mass index (BMI) ≥ 30 kg/m(2) (P < 0.001), and diabetes (P = 0.001).

CONCLUSIONS

Regadenoson CMR is well tolerated and can be performed safely with few adverse events.

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.

Prevalence and significance of electrocardiographic changes and side effect profile of regadenoson compared with adenosine during myocardial perfusion imaging

BACKGROUND

Significance of electrocardiogram (EKG) changes associated with regadenoson as well as side effects compared to adenosine in a real world, unselected population is unknown.

METHODS AND RESULTS

Three hundred ninety six consecutive patients undergoing either adenosine or regadenoson-based single-isotope (Technetium 99c) nuclear images were evaluated. A standard form documenting side effects was filled immediately following administration. The EKGs and nuclear scans were reviewed in a blinded-fashion. Commonest symptoms reported were flushing (64%), chest pain (36%) and dyspnea (36%). Flushing and chest pain were significantly more common with adenosine (73% vs. 57%, P < 0.01 and 53% vs. 47%, P = 0.06) and dyspnea more with regadenoson (40% vs. 31%, P = 0.05). Sixty (29%) patients carried a diagnosis of chronic bronchitis or asthma but only 4 (2 with each) required aminophylline. There was no significant correlation between chest pain induced by either agent or ischemia on nuclear imaging. EKG changes occurred infrequently (16% with regadenoson and 10% with adenosine), and had low sensitivity for detecting ischemia (7% for regadenoson and 11% for adenosine).

CONCLUSIONS

EKG changes with adenosine and regadenoson occur infrequently and have low sensitivity for detecting ischemia. Chest pain is frequently induced by both, and is not predictive of ischemia on nuclear imaging.

Regadenoson pharmacologic rubidium-82 PET: a comparison of quantitative perfusion and function to dipyridamole

BACKGROUND

Dipyridamole is used for stress (82)rubidium chloride ((82)RbCl) PET because of its long hyperemic duration. Regadenoson has advantages of a fixed dose and favorable symptom profile, but its mean maximal hyperemia is only 2.3 minutes. To determine its suitability for (82)RbCl PET, we imaged subjects using a regadenoson protocol based on its hyperemic response and compared the images in the same subjects having dipyridamole PET.

METHODS

In 32 subjects (23 M), we assessed visually by blinded interpretation and quantitatively compared summed stress and difference scores, total perfusion deficit (TPD), LVEF, LV volumes, and change in stress-rest function. Linear correlation and Bland-Altman analysis of the paired measurements were applied for evaluation of differences. Paired t test and Pearson's correlation were applied for testing of significance.

RESULTS

The images were interpreted the same by visual assessment. Twenty-six (26) subjects had reversible defects; by quantitation the SSS was 12.9 ± 7.0 and 14.1 ± 6.4 (P = .23) and SDS was 7.0 ± 6.8 versus 7.6 ± 6.2 (P = .40) for dipyridamole and regadenoson, respectively. Six (6) subjects had <5% likelihood of CAD and were normal by both. All paired measurements showed a high positive correlation between regadenoson and dipyridamole; stress segmental perfusion Reg = 0.93Dip + 4.4, r = 0.88; TPD Reg = 0.94Dip + 0.41, r = 0.93; LVEF Reg = 0.92Dip + 4.7, r = 0.95; stress minus rest LVEF Reg = 0.87Dip - 0.99, r = 0.82.

CONCLUSION

Regadenoson stress (82)RbCl PET perfusion defect and cardiac function measurements are visually and quantitatively equivalent to dipyridamole studies and can be obtained with the clinical advantages of regadenoson.

Patient- and clinician-reported satisfaction with pharmacological stress agents for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI)

OBJECTIVE

The objective of this study was to compare clinician and patient measures of satisfaction with two pharmacological stress agents (PSA), regadenoson and dipyridamole, used in Single Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging (MPI).

METHODS

This observational study included patients who had undergone SPECT MPI with regadenoson or dipyridamole, as well as the clinician/clinical technologist who performed the test. Mean scores for individual item and domain scores of the main outcome measures were computed as well as the effect sizes (ES) of the mean difference in scores between treatment groups. Statistical significance of the mean item and domain score differences were assessed via Mann-Whitney tests.

MAIN OUTCOME MEASURES

Two self-report questionnaires which had beeb previously developed and validated: Patient Satisfaction/Preference Questionnaire (PSPQ) and Clinician Satisfaction/Preference Questionnaire (CSPQ).

RESULTS

A total of 87 patients (68 received regadenoson, 19 received dipyridamole) and nine clinicians/clinical technologists took part in the study. Patients had a mean age of 66.8 ± 12.2 years, and 56.3% were male. Compared to dipyridamole, use of regadenoson was associated with greater clinician satisfaction on all items and domains of the CSPQ (p < 0.001 for all comparisons). Among patients, regadenoson was associated with less bother and greater satisfaction than dipyridamole for all items on the PSPQ. These patients reported less stinging at the injection site (ES = -0.66) and less nervousness during injection (ES = -0.60). The PSPQ found that regadenoson patients were more satisfied with their PSA than dipyridamole patients in all areas.

LIMITATIONS

This study utilized a relatively small sample size of dipyridamole patients and lacked an adenosine group. A broader sampling of professionals would also help demonstrate generalizability.

CONCLUSION

Both patients and clinicians reported higher satisfaction with regadenoson compared to dipyridamole for SPECT-MPI. Clinicians were particularly satisfied with the preparation and administration aspects of the drug, while patients rated it highly on convenience and reduced incidence of side-effects.

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.