(aspirin, caffeine)4
(acetaminophen, aspirin, caffeine)5
(acetaminophen, butalbital, caffeine)9
(caffeine)6
(acetaminophen, butalbital, caffeine)10
(caffeine)7
Efficiency is often important in a busy nuclear cardiology lab. Anticipating challenges that can disrupt the daily workflow and implementing strategies to address the underlying issues can help avoid unnecessary interruptions.
Exercise stress testing is the gold standard and provides diagnostic and prognostic information. Adequate exercise requires patients to reach ≥85% of the maximum predicted heart rate (MPHR). Exercise tests should be symptom-limited and not stopped because adequate exercise is achieved.1 Exercise testing may need to be aborted if the patient experiences symptoms such as moderate-to-severe chest pain, excessive shortness of breath, or fatigue.1 Preparing patients for both exercise and pharmacologic stress testing may help avoid canceled or rescheduled tests and improve the patient experience.
Use the calculator below to help determine 85% of a patient’s MPHR2:
MPHR calculator developed by Astellas.
For patients who are unable to adequately exercise and need pharmacologic stress, abstaining from xanthine-containing substances such as caffeine and theophylline is important for achieving accurate results.3 Counseling patients on what to avoid before the pharmacologic stress test can help prevent the need for cancellation or rescheduling. Below, please find a nonexhaustive list of things patients should avoid if undergoing a pharmacologic stress test.
Technical and patient-related issues that can cause artifacts may arise during stress myocardial perfusion imaging (MPI). Artifacts can lead to false-positive results.16,17
Patient Motion
When patients are uncomfortable during image acquisition, they are more likely to create motion artifacts and compromise data integrity, as stated in an article from the Journal of Nuclear Medicine Technology. Patients may have discomfort due to illness, back pain, lack of flexibility, fatigue, or anxiety.16
Technical Issues
Periodic inspection and recalibration of MPI cameras, as recommended by the Intersocietal Accreditation Commission (IAC), is necessary.17 Always refer to the manufacturer’s recommendations for periodic assessment of scintillation cameras.
Certain patient populations pose unique challenges when imaging for coronary artery disease (CAD). For example, the stressor (exercise or pharmacologic) used in MPI testing in women and patients with left bundle-branch block (LBBB), implantable cardiac pacemakers, chronic kidney disease (CKD), or asthma or chronic obstructive pulmonary disease (COPD) requires special considerations for achieving quality imaging results.1,3,18-21
During exercise MPI, images from patients with LBBB often display false-positive defects. Because reversible septal perfusion defects can occur in non-CAD patients with LBBB who are stressed with exercise, vasodilator pharmacologic stress has become the preferred method of MPI.3
In patients with implantable cardiac pacemakers, vasodilator pharmacologic stress is the preferred method for MPI.3
All patients with CKDa should be considered at increased risk for subsequent cardiovascular disease (CVD) events, according to the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI).21 CVD is the leading cause of death in patients with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2.18 Even less severe CKD is an independent risk factor for CVD.21
Cardiac imaging in patients with CKD may have challenges:
Because of these factors, pharmacologic stress MPI may be preferred for patients with CKD.19
aDefined as abnormalities of kidney structure or function (eGFR <90 represents reduced glomerular filtration) for >3 months.
ASNC Imaging Guidelines recommend using caution when administering certain vasodilatory stress agents to patients with asthma or COPD because of the potential for vasodilator-induced bronchospasm.1
The clinical evaluation of women may be challenging due to factors such as20,22:
Also, women may have smaller heart size compared with men, which can result in blurred images and potentially lower test sensitivity.20
According to a consensus statement by the American Society of Nuclear Cardiology (ASNC), radionuclide imaging with either SPECT or positron emission tomography (PET) MPI can effectively risk stratify women with intermediate-to-high pretest probability of stable ischemic heart disease (SIHD).20 While exercise stress is the preferred method of noninvasive testing,22 women may have limited exercise capacity due to older age and comorbidities.20 Pharmacologic stress testing provides an alternative for those who are unable to exercise adequately.20
With the increasing focus on delivering efficient, cost-conscious imaging, trained nonphysician providers may conduct exercise stress tests under a physician's supervision according to American Hospital Association (AHA) guidelines.23 The degree of supervision needed should be determined by the physician based on the patient’s clinical status. This can help contain costs while maintaining quality of care.23
American Society of Nuclear Cardiology (ASNC) guidelines recommend performing an MPI stress test first and, if the stress test results are normal, canceling the rest test. This minimizes radiation exposure during a 1-day study. In obese patients for whom a 2-day study is appropriate, ASNC guidelines recommend performing the stress test first, using attenuation correction if available, and canceling the rest study if the stress test results are normal.24
References+
1. Henzlova MJ, Duvall WL, Einstein AJ, Travin MI, Verberne HJ. ASNC imaging guidelines for SPECT nuclear cardiology procedures: stress, protocols, and tracers. J Nucl Cardiol 2016:23(3):606-39. Erratum in: J Nucl Cardiol 2016;23(3):640-2. 2. Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol 2001;37(1):153-6. 3. DePuey EG, Mahmarian JJ, Miller TD, et al. Patient-centered imaging. J Nucl Cardiol 2012;19(2):185-215. Erratum in: J Nucl Cardiol 2012;19(3):633. 4. Anacin [package insert]. Tarrytown, NY: Insight Pharmaceuticals LLC. 5. Excedrin [package insert]. Warren, NJ: GlaxoSmithKline Consumer Healthcare Holdings (US) LLC. 6. Vivarin [package insert]. East Windsor, NJ: Vespyr Brands, Inc. 7. NoDoz [package insert]. Cedar Rapids, IA: Lil’ Drug Store Products, Inc. 8. Ergotamine tartrate, caffeine [package insert]. Atlanta, GA: MIKART, INC. 9. Esgic [package insert]. Atlanta, GA: MIKART, LLC. 10. Fioricet [package insert]. Parsipanny, NJ: Teva Pharmaceuticals USA, Inc. 11. Butalbital, aspirin, and caffeine [package insert]. Kansas City, MO: Nostrum Laboratories, Inc. 12. Aggrenox [package insert]. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc. 13. Dipyridamole [package insert]. Pennington, NJ: Zydus Pharmaceuticals USA Inc. 14. Elixophyllin [package insert]. Bryan, OH: Nostrum Laboratories, Inc. 15. Theo-24 [package insert]. Caguas, PR: Neolpharma, Inc. 16. Wheat JM, Currie GM. Incidence and characterization of patient motion in myocardial perfusion SPECT: Part 1. J Nucl Med Technol 2004;32(2):60-5. 17. Intersocietal Accreditation Commission. The IAC standards and guidelines for nuclear/PET accreditation (06-23-2023). https://intersocietal.org/wp-content/uploads/2023/06/IACNuclearPETStandards2023.pdf. Accessed 06-23-2023. 18. Thompson S, James M, Wiebe N, et al. Cause of death in patients with reduced kidney function. J Am Soc Nephrol 2015;26(10):2504-11. 19. Okwuosa T, Williams KA. Coronary artery disease and nuclear imaging in renal failure. J Nucl Cardiol 2006;13(2):150-5. 20. Taqueti VR, Dorbala S, Wolinsky D, et al. Myocardial perfusion imaging in women for the evaluation of stable ischemic heart disease-state-of-the-evidence and clinical recommendations. J Nucl Cardiol 2017;24(4):1402-26. 21. Kidney Disease Improving Global Outcomes. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int Suppl 2013;3(1):1-150. 22. Fihn SD, Gardin JM, Abrams J, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease. J Am Coll Cardiol 2012;60(24):e44-164. Erratum in: J Am Coll Cardiol 2014;63(15):1588-90. 23. Myers J, Forman DE, Balady GJ, et al. Supervision of exercise testing by nonphysicians: A scientific statement from the American Heart Association. Circulation 2014;130(12):1014-27. 24. Cerqueira MD, Allman KC, Ficaro EP, et al. Recommendations for reducing radiation exposure in myocardial perfusion imaging. J Nucl Cardiol 2010;17(4):709-18.