Looking for Coronary Disease in Patients With Atrial Fibrillation

Abstract

Canadian Journal of Cardiology 30 (2014) 861e863 Editorial Looking for Coronary Disease in Patients With Atrial Fibrillation Payal Kohli, MD, and David D. Waters, MD Division of Cardiology, San Francisco General Hospital, and the Department of Medicine, University of California, San Francisco, San Francisco, California, USA See article by Tsigkas et al., pages 920-924 of this issue. “Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong remedies.” dGroucho Marx Atrial fibrillation (AF) is common in older individuals with risk factors. Coronary artery disease (CAD) is common in older individuals with risk factors too, and several risk factors for AF and CAD overlap, such as hypertension, diabetes, and obstructive sleep apnea. It should therefore surprise no one that CAD is present in many patients with AF. What should we do about it? Specifically, how aggressively should we look for CAD in patients with AF? And when CAD is silent, what should we do about it when we find it? We should be careful to avoid Groucho’s definition of politics: looking for trouble, finding it everywhere, diagnosing it incorrectly, and applying the wrong remedies. Prevalence of Coronary Disease in AF Patients The prevalence of CAD reported in patients with AF varies according to how patients are selected and how CAD is diagnosed. Results from several representative studies are listed in Table 1. 1-8 The prevalence ranges from 22% to 49%, with the lowest prevalence observed in the study of Tsigkas et al., published in this issue of the Canadian Journal of Cardiology. 8 The clinical factors predictive of CAD in patients with AF tend to be the same as in patients without AF, with older age, male sex, and smoking predominating. 3-5,7 Myocardial Ischemia in AF Patients If approximately a third of patients with AF have under- lying CAD, it should be quite straightforward to detect them with noninvasive modalities such as stress testing. In fact, the rapid ventricular rate that is often seen in patients with AF has been termed a stress test equivalent, and ST depression occurring at these rates has been attributed to subendocardial Received for publication June 4, 2014. Accepted June 6, 2014. Corresponding author: Dr David D. Waters, Room 5G1, San Francisco General Hospital, 1001 Potrero Ave, San Francisco, California 94114, USA. E-mail: dwaters@medsfgh.ucsf.edu See page 862 for disclosure information. myocardial ischemia. In the study of Tsigkas et al., ST depression was seen in 44 of 115 patients with rapid AF, defined as rates >80% of maximum predicted heart rate, and half of them had CAD at angiography. 8 Perhaps the most clinically useful finding in their study is that only 3 of the 71 patients without ST depression during rapid AF had positive noninvasive tests for myocardial ischemia and CAD at angi- ography. Clearly, performing coronary angiography or even noninvasive stress testing in all of these patients would be an overreaction. In contrast, 22 of the 44 patients with ST depression during rapid AF had CAD at angiography. This finding is not of great clinical use because the pretest probability of CAD based on previous studies was 1 in 3 and the posttest prob- ability based on this study is 1 in 2. In another study, only 11 of 35 patients with ST depression during rapid AF had obstructive CAD at angiography. 4 Therefore, electrocardio- graphic stress testing might have a limited role in diagnosing CAD in AF patients. More sophisticated ways to detect myocardial ischemia such as stress nuclear imaging are also plagued by a high rate of false positives in patients with AF, perhaps because of problems with gating for patients in AF at the time of the study, or because of problems with coronary flow regulation. For example, in 1 study, single-photon emission computed tomography detected myocardial ischemia in 13 AF patients, only 2 of whom had coronary disease at angiography. 9 In another study, thallium scintigraphy was falsely positive in 23 of 56 AF patients without CAD (and truly positive in 23 of 27 AF patients with CAD). 5 In that study, myocardial contrast stress echocardiography was the only test with an acceptably high specificity. However this test is not without problems in AF patients. Dobutamine stress echocardiography might trigger a rapid ventricular rate, complicating the hemodynamic loading conditions and the interpretation of wall motion abnormal- ities. In 1 large study, a history of AF increased the odds of developing AF during dobutamine stress echocardiography by 18.4-fold. 10 As discussed by Tsigkas et al., AF might induce coronary vasoconstriction or a failure of appropriate coronary flow regulation, such that myocardial ischemia occurs in the 0828-282X/$ - see front matter O 2014 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cjca.2014.06.001