Follow-up provocative testing fails to find coronary artery disease

Aaron Lear

Follow-up provocative tests were not likely to discover coronary artery disease in patients with low pretest probability and observed or admitted to the hospital after ED presentation with chest pain, according to findings recently published in the Journal of the American Board of Family Medicine.

Perspective from Michelle M. Kittleson, MD, PhD

“In the United States, once patients at low risk for [acute coronary syndrome] are admitted for observation or to inpatient units, and determined not to have [acute coronary syndrome], there is wide variability in the decisions made regarding provocative stress testing and further confirmatory imaging of coronary arteries,” Aaron Lear, MD, CAQ, of Akron General Family Medicine in Ohio, and colleagues wrote.

“It is unclear what leads to this variability in decision making, and what affect this variability has on patient outcomes. Several recent studies suggest that it may be safe and appropriate to release patients considered to have low pretest probability for [coronary artery disease] from the hospital after it has been determined they are not having [acute coronary syndrome] without progressing to provocative stress testing,” they added.

Researchers used the Duke Clinical Score to classify 238 patients as moderate/high pretest probability for coronary artery disease and 305 patients as low pretest probability for the same condition. Patients were aged 30 to 70 years, had no prior coronary artery disease diagnosis and were admitted to observation or inpatient status based on chest pain or related complaints.

Lear and colleagues found that among the two groups, neither rates of positive or equivocal stress tests (RR = 0.653; 95% CI, 0.415–1.028) nor rates for stress testing (RR = 1.01; 95% CI, 0.852–1.192) showed a difference. In addition, patients with low-pretest-probability had a lower probability of positive coronary imaging following the stress test (RR = 0.061; 95% CI, 0.004–0.957).

“Our findings confirm our hypothesis that patients with no previous diagnosis of [coronary artery disease], admitted to observation or inpatient status for serial cardiac enzymes and further evaluation of their chest pain may be at increased risk for unnecessary coronary angiogram,” Lear and colleagues wrote.

“We believe these findings speak to the implications of national guidelines, which pay attention to the benefit of testing and diagnosis, and pay little heed to risks inherent in testing those that have little risk for disease. We believe the mounting evidence calling into question the current blanket recommendations for provocative stress testing by the [American Heart Association] should be revisited,” they added.

Lear also discussed how primary care physicians can implement these findings with their patients in an interview with Healio Family Medicine.

“PCPs should let patients know that: one, a negative stress test is not protective for having acute coronary syndrome in the future; two, we should only perform the stress test if there is a fair chance one actually has coronary artery disease; and three: having a positive stress test in the setting of one with low risk for coronary artery disease is more likely to be a false positive test, than it is to suggest coronary artery disease.”

“It is [also] notable that there is evidence suggesting that aggressive diagnostic testing for coronary artery disease may not really lead to much good. There is historic evidence suggesting that medical management is as effective as percutaneous interventions and more recent research suggesting that the chest pain ‘benefit’ one gets after a stent may simply be placebo-and not necessarily long lasting,” he continued. “In light of findings such as these, aggressive management of risk factors (smoking, sedentary life, hypertension) may be the most appropriate way to deal with low risk chest pain with persisting problems, or it may be appropriate to consider stress testing, or even cardiology referral.” – by Janel Miller

Disclosure: The authors report no relevant financial disclosures.

Perspective

Michelle M. Kittleson, MD, PhD

There are a few pearls of wisdom from medical school that remain with me two decades hence: 1) differential diagnosis is a funnel that starts with the history and moves on to diagnostic testing such that testing is only done to confirm a diagnosis already suspected after the history and 2) don’t check a test if you already know the answer. This study by Lear and colleagues illustrates why these timeless pearls hold true.

In this retrospective analysis, 543 patients with no known coronary artery disease who presented to the emergency department with chest pain classified by the Duke Clinical Score. The Duke Clinical Score, published in 1983, classifies patients as having low or moderate/high risk for coronary artery score based on the history: age, sex, nature of chest discomfort, and risk factors. More than half the cohort, 305 patients, were in the low-risk category. However, half of the low-risk patients still underwent stress testing, the same rate as patients in the moderate/high risk category, thus violating pearl number 1: if the history does not suggest coronary artery disease, then testing to assess for coronary artery disease is not warranted.

Ultimately, 27 patients in the low-risk group by history had positive or equivocal stress tests, and 16 went on to coronary angiography or CT coronary angiography — and none had significant coronary artery disease. Of course, this is not surprising; the history holds true and Bayes’ Theorem reigns supreme. A hallmark of the medical student biostatics curriculum, Bayes‘ Theorem describes how pretest probability affects posttest probability. According to this theorem, if the pretest probability is low, then a positive test is more likely a false-positive than a true-positive. Or, from pearl number 2: don’t check a test if you already know the answer.

However, due to lack of confidence in one’s clinical skills, or concern about the increasingly litigious culture we struggle with, these pearls of wisdom may be easier quoted than practiced. But how incredible that a clinical risk score formulated in 1983 holds true today, 35 years later, because the pathophysiology of angina and the art of history-taking remains constant.

So what should we take away from this study? Obtain a history that you are confident with, and it will guide you in the choice and timing of appropriate testing. In doing so, you will save the health care system from needless expenditure and most importantly, save patients from unnecessary worry, inconvenience, and risk.

Michelle M. Kittleson, MD, PhD

Director, Heart Failure Research

Director, Post-Graduate Education in Heart Failure and Transplantation

Associate Professor of Medicine, Smidt Heart Institute, Cedars-Sinai

Disclosures: Kittleson reports no relevant financial disclosures.

Sources/Disclosures

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Source:

Lear A, et al. J Am Board Fam Med. 2018;doi:10.3122/jabfm.2018.02.170295.