Three days later, you notice that Mrs. S is still an inpatient. She had a positive stress test and subsequently underwent a cardiac catheterization that was negative for any significant coronary vessel disease. Post catheterization, Vascular Surgery was consulted because she had unfortunately developed a femoral artery pseudoaneurysm. Femoral artery vascular complications such as pseudoaneurysm and hematomas occur in up to 6% of cases, and other complications include dissection, thrombosis and infection [4,5,6].

The Coronary Artery Surgery Study (CASS) found that the pretest probability of coronary artery disease (CAD) varied between 5% and 89% based on age, sex, and chest pain characteristics [7]. Risk factors for CAD include chest pain consistent with angina, age, gender, history of diabetes or hyperlipidemia, and smoking. The current American College of Cardiology/American Heart Association guidelines for stress testing recommend assessment with an imaging modality (i.e. stress ECHO) for patients that are at intermediate risk for CAD. Any of the following factors suggests an intermediate risk: Prior history of CAD, ECG with ST-segment depression 0.05 to <0.10 mV and/or flat or inverted T waves <0.20 mV deep, diabetes mellitus, chronic kidney disease, and advanced age [8, 9, 10, 11].

With the rising costs of healthcare in the U.S., the American College of Physicians has called for more judicious use of screening and diagnostic tests. One principle they emphasize is that when the pretest probability of disease is low, the likelihood of a false positive test result is higher than a true positive test result [12]. Namely, cardiac stress testing in patients that are low risk for CAD is not recommended because the low pretest probability of this study in this population leads to subsequent higher likelihood for false positives and increased needless downstream interventions with their own rates of harm. Of note, the inverse is also true; those with a very high pretest probability are more likely to have a false negative result. Moreover, a retrospective study in 2013 by Foy et al demonstrated that out of 2662 patients without a history of CAD that had a cardiac catheterization, 866 were preceded by a stress imaging, with a pretest probability of 18% PPV for stress echocardiogram, and 27% for single-photon emission computed tomography. While this study is limited by the biases inherent to a retrospective study, it does suggest that too many stress tests are currently being ordered on low risk patients [13].

Mrs. S was low risk by her HEART score of 2 and had a low pretest probability for CAD based on the data from the CASS study, and was therefore at higher risk for a false positive result with cardiac stress testing. Furthermore, the downstream testing as a result of a positive stress test puts patients at risk for adverse events due to the invasive nature of cardiac catheterization and its complications. Mrs. S intuitively suspected that her risk for CAD was low, and as her physicians we should have easily and accurately made that assessment ourselves. As demonstrated by Hess et al, a better approach would have been to engage the patient in shared decision-making, which would have given her input into the management plan, and likely avoided this complication. While some physicians aim to reduce medico-legal liability by ruling out ACS with a stress test, our patients are exposed to over testing and even injury when this test is used indiscriminately. The cardiac stress test is to be used as a diagnostic tool in the correct clinical context, and a false positive result in a patient with a low pretest probability of disease may not only lead to complications, but also could have been determined without the test altogether.

Submitted by Aldo Andino, PGY-3

Peer Reviewed by Alicia Oberle, PGY-4

Faculty Reviewed by Douglas Char

Professor, Emergency Medicine, Washington University School of Medicine

References:

[1] Emerg Med J. 2014 Apr;31(4):281-5. doi: 10.1136/emermed-2012-201323. Epub 2013 Apr 10.

[2] Crit Pathw Cardiol. 2011 Sep;10(3):128-33.

[3] Circ Cardiovasc Qual Outcomes. 2012 May;5(3):251-9.

[4] Am J Cardiol. 1992;69(1):63.

[5] Am J Cardiol. 1993;72(13):47E.

[6] Circulation. 1993;88(4 Pt 1):1569.

[7] N Engl J Med. 1979;301:230-235.

[8] J Am Soc Echocardiogr. 2011 Mar;24(3):229-67. doi: 10.1016/j.echo.2010.12.008.

[9] J Am Coll Cardiol. 2002;40(8):1531.

[10] Circulation. 2009;119:e561-e587.

[11] J Am Soc Echocardiogr. 2011 Mar;24(3):229-67.

[12] Ann Intern Med. 2012 Jan 17;156(2):147-9.

[13] Am J Med Qual. 2014 Mar-Apr;29(2):153-9

The Hippocratic Medicine series is modeled after the Do No Harm project pioneered at the University of Colorado. The aim of this series is to raise awareness about the avoidance of avoidable care i.e. for how medical overuse has the potential to do patient harm. Because every test or intervention we do has the potential for not just benefit but also harm, we should seek that our patients do better because of the care we provide instead of despite it. The WUSM Hippocratic Medicine Series is supported by a grant provided by the Foundation for Barnes Jewish Hospital.