April 13th, 2012

CT Angiography for Safe Discharge of Patients

(Reprinted with permission from NOW@NEJM, a blog for physicians about the New England Journal of Medicine)

Chest pain is the second most common reason for Emergency Room visits in this country, and although only 10-15% of patients admitted with chest pain are ultimately diagnosed with an acute coronary syndrome, the majority of patients get admitted. So common, in fact, is this admission diagnosis, that during cardiology rounds the other week, when I asked a resident how the patient was doing, she responded, “Oh fine, we’re just rome-eee-ing him,” (a new twist on the acronym “ROMI” for “Rule out MI”). Sure, on a busy floor, it’s easy enough to deem the “soft” rule-outs as unnecessary. But put yourself in the shoes of the ED docs. GI distress from a bad tuna sandwich can look a lot like the pain of unstable plaque. So how to decide who is safe to go home?

One method that has shown initial promise is Coronary CT Angiography, (CCTA), which in previous trials has demonstrated a robust negative predictive value among patients with low to intermediate risk of CAD. However, previous trials were not statistically powered to really answer the question as to whether CCTA was a safe strategy to effectively triage patients who required some further form of testing*. Thus, in this week’s NEJM, Litt et al present the results of “CT Angiography for Safe Discharge of Patients with Possible Acute Coronary Syndromes,” a “real-world” trial which aims to get at this lingering question.

The study, which included five sites, enrolled low to intermediate risk patients who presented to the ED with chest pain and possible ACS. Patients were 30 years or older, with symptoms possibly representing ACS, TIMI, (Thrombolysis in Myocardial Infarction), scores between 0 to 2, and ECGs that were without evidence of acute ischemia. The study was powered to address the hypothesis that patients without CCTA evidence of coronary-artery stenoses ≥50% would have a 30-day rate of cardiac death or myocardial infarction of less than 1%. Secondary outcomes included rates of discharge from the ED, length of stay if admitted, and 30-day rates of death, myocardial infarction, revascularization, and resource utilization.

Nearly 1400 patients were randomized in a 2:1 fashion to either CCTA, or usual care, (the treating team decided which tests, if any, were warranted). Of the 908 patients assigned to the CCTA strategy, 84% ultimately underwent CCTA, with tachycardia, an impediment to image acquisition, being the most common reason for failure to undergo testing. Notably, 64% of patients in the usual care arm underwent some form of diagnostic testing. Among the 640 patients found to have a negative CCTA, there were no deaths or MIs within 30 days of presentation, thus confirming the study’s primary hypothesis. Regarding secondary outcomes, it was notable that patients in the CCTA group were more likely to be discharged from the ED, had shorter length of stay when admitted, and were more likely to be identified as having coronary disease on invasive angiography.

But does this answer our question: is CCTA a safe strategy to effectively triage low risk chest pain patients in the ED? I think the jury’s still out. What this study suggests is, if your patient in the ED has a negative CCTA, he’s safe to go home. However, the study was not adequately powered to address whether CCTA should be the standard ED strategy to make triage decisions in these low risk chest pain patients. Unfortunately, studies of diagnostic testing among low risk patients are extremely challenging, as event rates are so low that more patients, more time, and more money, are required to really answer whether this strategy, per se, is safe. As we await further trials, I suspect we will continue to do a lot of ro-mee-ing on the floor.

* Goldstein JA, Chinnaiyan KM, Abidov A, et al. The CT-STAT (Coronary Computed Tomographic Angiography for Systematic Triage of Acute Chest Pain Patients to Treatment) trial J Am Coll Cardiol 2011;58:1414-1422

3 Responses to “CT Angiography for Safe Discharge of Patients”

  1. Stephen Fleet, MD says:

    I think coronary CT angiography is the perfect test for these patients. Unfortunately, it will take a while for the paradigm to shift in terms of work-up.

  2. I agree that CCTA is the perfect test for these patients. It is capable of diagnosing the presence or absence of coronary disease as well as the presence or absence of myocardial infarction.

    A large percentage of patients ruled out with serial enzymes or stress imaging can still have significant coronary artery disease missed by these older and less accurate technologies.

    I fail to see why we need to wait for more information. Is the problem that in a fee for service world, a penny saved is a penny not earned?

  3. Jean-Pierre Usdin, MD says:

    CACT and what else?
    Big show at the ACC in Chicago in favor of the star: Coronary Artery C T scan (CACT)! More than 2000 patients and 2 trials to allow the discharge of low risk ACS patients: big success! But…what else?
    How to adapt these results in real life? Radiologists specialized in this specific CT scan in the field? As the urgentists and cardiologists 24/24 7/7? The doubt is in my mind.
    What about the non conclusive CT scan (the rate was not reported)? The patient stays and wait for 48 hours before having a (normal?)Coronary angiogram? this will be real life!

    Another story about the big star CACT: a group of cardiologists of Ottawa (Tandon V.et coll: Rates of downstream invasive coronary angiography… Eur. Heart J. 2012 (33) 776-82)reported 1200, low risk! patients (I suppose suffering from chest pain) who underwent CACT.
    only 10% had coronary angiogram and 6% (of the whole group) had coronary revascularization. So great!
    what about the other (90%patients!) not evaluated by angiogram? my opinion is: too many patients had an unjustified ionizing high cost CACT.
    Where is the physician point of view and the (old but sometimes useful) Stress test? In this study, in fact, CACT was compared to matched 1200 patients having SPECT myocardial imaging . Here again 10% had coronary angiogram. Are we asking too sophisticated and unjustified tests?
    So what?
    CACT super star, I am not so sure in my clinical practice!
    And after reading the recommendations of “Choosing Wisely” the “Five things Physicians and Patients Should Question” of ACC I am true