Vasodilator stress agents for myocardial perfusion imaging

Journal of Nuclear Cardiology, Feb 2016

Rayan Saab MD, Fadi G. Hage MD, FASH, FASNC, FACC

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Vasodilator stress agents for myocardial perfusion imaging

Received Jan Vasodilator stress agents for myocardial perfusion imaging Rayan Saab 0 2 Fadi G. Hage 0 FASNC 0 0 Reprint requests: Rayan Saab, MD, Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham , Lyons Harrison Research Building 306, 1720 2nd Ave S, Birmingham, AL 35294-0007 1 Section of Cardiology, Birmingham Veterans Affairs Medical Center , Birmingham, AL 2 Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham , Birmingham, AL - In this issue of the Journal, Yao et al report on the prognostic value of adenosine triphosphate (ATP) myocardial perfusion imaging (MPI) with Technetium99 sestamibi (Tc-99m) in a population aged 70 years and older.1 The ability to exercise in this population is expected to be rather limited. A total of 415 patients with suspected coronary artery disease (CAD) were identified and retrospectively enrolled in the study. The primary composite end point was major adverse cardiac events (MACE) and included death from a cardiac etiology, nonfatal myocardial infarction (MI), and late coronary revascularization ([60 days). Sixteen patients met exclusion criteria as they underwent early coronary revascularization B60 days after MPI. Reversible and/or fixed perfusion defects were considered abnormal and patients were followed over a mean of 3.45 ± 1.71 years. MACE occurred in 37 patients, including 9 cardiac deaths, and was significantly lower in patients with normal MPI, even after adjusting for other variables such as age [80 years, male gender, chest pain or dyspnea, hypertension, hyperlipidemia, diabetes mellitus, chronic kidney disease, atrial fibrillation, and abnormal ATP stress ECG. Each of the individual outcomes included in MACE was also significantly lower in patients with normal MPI. In addition, although patients aged C80 years had higher MACE rates than those aged 7079 years when the summed stress score (SSS) was [8, the two groups had similar MACE rates when the SSS was B8. These results confirm the prognostic value of ATP-MPI in an elderly population with suspected CAD. The proportion of pharmacologic stress tests performed in the United States has steadily increased over the past several decades. Exercise stress testing is favored over vasodilator stress, since it is more physiological and since it assesses the functional capacity which provides important prognostic information.2 However, when patients are not able to achieve a specified gender and age-adjusted target heart rate and exercise capacity, the test loses some of its diagnostic and prognostic value. Further, a significant proportion of the population in developed countries is unable to exercise. This is likely the primary driver of the 23% drop in the rates of exercise stress tests in 2006-2009 as compared to 1991-1995.3 In these instances, and in other special circumstances, such as the presence of left bundle branch block or ventricular paced rhythm, pharmacologic stress agents are used for myocardial perfusion imaging. Pharmacologic stress agents currently in use fall under two categories: the inotropes/ chronotropes that trigger a stress response by increasing myocardial oxygen demand, and the vasodilator agents that primarily trigger coronary vasodilation.4 The former include dobutamine, arbutamine, and higenamine, a b-receptor agonist derived from a traditional Chinese medicine which is currently undergoing clinical trials in China. The latter, which will be the focus of our discussion, include dipyridamole, adenosine, adenosine triphosphate (ATP) and regadenoson (Table 1). Of the vasodilator agents mentioned, ATP, the pharmacologic stress agent used in the study by Yao et al,1 is not approved for use in the United States but is being used in other parts of the world including Japan and China. The currently used vasodilator stress agents all mediate their effects, either directly or indirectly, s e tc ? id fe ? ? 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It also constitutes the nucleoside base of both ATP and cyclic adenosine monophosph (...truncated)


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Rayan Saab MD, Fadi G. Hage MD, FASH, FASNC, FACC. Vasodilator stress agents for myocardial perfusion imaging, Journal of Nuclear Cardiology, 2017, pp. 434-438, Volume 24, Issue 2, DOI: 10.1007/s12350-016-0408-4