It's Not Useful to Stress Those <40 YO

[docB]

From the July 2009 Annals:

The Limited Utility of Routine Cardiac Stress Testing in Emergency Department Chest Pain Patients Younger Than 40 Years

Luke K. Hermann, MDa, Scott D. Weingart, MDb, W. Lane Duvall, MDc, Milena J. Henzlova, MDc


Received 24 October 2008; received in revised form 12 December 2008; accepted 7 January 2009. published online 23 February 2009.

Study objective
This is a study designed to evaluate the utility of routine provocative cardiac testing in low-risk young adult (younger than 40 years) patients evaluated for an acute coronary syndrome in an emergency department (ED) setting.

Methods
This was a retrospective observational study of patients aged 23 to 40 years who were evaluated for acute coronary syndrome in an ED-based chest pain unit from March 2004 to September 2007. All patients had serial cardiac biomarker testing to rule out myocardial infarction and then underwent provocative cardiac testing to identify the presence of myocardial ischemia. Patients were excluded from the study if they had known coronary artery disease, had ECG findings diagnostic of myocardial infarction or ischemia, or self-admitted, or tested positive for cocaine use.

Results
Of the 220 patients who met inclusion criteria, 6 patients (2.7%; 95% confidence interval 1% to 5.8%) had positive stress test results. Among these 6 patients, 4 underwent subsequent coronary angiography that demonstrated no obstructive coronary disease, suggesting the initial provocative study was falsely positive. For the remaining 2 patients, no diagnostic angiography was performed. Discounting the patients who had negative angiography results, only 2 of 220 study patients (0.9%; 95% confidence interval 0.1% to 3.2%) had a provocative test result that was positive for myocardial ischemia.

Conclusion
In our study, a combination of age younger than 40 years, nondiagnostic ECG result, and 2 sets of negative cardiac biomarker results at least 6 hours apart identified a patient group with a very low rate of true-positive provocative testing. Routine stress testing added little to the diagnostic evaluation of this patient group and was falsely positive in all patients who consented to diagnostic coronary angiography (4 of 6 cases).

Wow! So can we quit admitting all of those <40 yo CP rule outs? Probably not because the N for this is relatively small but it's an interesting study. Note that it just flat says there's no utility in stressing the <40 set. It doesn't go into risk factors, typical vs. atypical pain, etc. It just says it's not useful.

If some more studies bear this out we might be in for a big and welcomed change. But there's a truthful caveat in the conclusion of the full text that notes correctly:

[The current] practice is unlikely to change until physicians do not feel at risk for missing a single patient with acute coronary syndrome.

Abstract in Annals

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[Arcan57]

I'd be much more impressed if it was done as a prospective study. The math makes sense though. Very low risk population + moderately sensitive/specific test = not useful. But as mentioned the N is small, and the methodology is only hypothesis generating. I doubt there is an EP in this great nation that doesn't want this result to be true though.

 

[BADMD]

Not really a surprise to me. When I was an MS-3, my IM preceptor was a cardiologist. One day he pulled out a list of pre and post test probabilities for stress tests based on age and the probabilities of false positives.

Based on the table he showed us, for a patient under 40, the chance of a true positive and the chance of a false positive were the same.