Coronary Computerized Tomography Angiography for Rapid Discharge of Low-Risk Patients with Cocaine-Asociated Chest Pain

October 18, 2009, 12:34 pm

★☆☆☆☆

CORONARY COMPUTERIZED TOMOGRAPHY ANGIOGRAPHY FOR RAPID DISCHARGE OF LOW-RISK PATIENTS WITH COCAINE-ASSOCIATED CHEST PAIN Walsh KM et al. J Med Toxicol Sept. 2009;5:111-119.

Abstract

In this observational study from the University of Pennsylvania, 59  patients with low-risk cocaine-associated chest pain received an emergency department workup that included either immediate coronary computerized tomography angiography (coronary CTA) without determination of serial cardiac markers, or coronary CTA after an observation period and serial markers.  Cocaine-associated was defined as any history of cocaine use either patient report or positive urine test.  Low-risk was not specifically defined. The main outcome studied was cardiovascular death or myocardial infarction within 30 days.

Study patients had a mean age of 45.6 years. The EKG was normal or non-specific in 79%, the the TIMI score < 2 in 85%. On coronary CTA, 6 patients had coronary stenosis > 50%. During the 30-day follow-up period, no patient died and no patient had a myocardial infarction.

COMMENT: This approach to chest pain — particularly cocaine-associated chest pain — seems to misguided that it’s difficult to know where to start.  Most of the problems with it were laid out in David Newman’s brilliant editorial in Annals of Emergency Medicine (March 2009;53:305) that commented on a similar study from the same authors that used coronary CTA to evaluate all low-risk chest pain.  As Dr. Newman pointed out: “CT angiography is therefore a method to identify the possibility of coronary stenosis, which, if present, indicates the possibility of myocardial ischemia, which, if present, indicates danger.”  Thus, coronary CTA not only fails to answer the important questions (is this chest pain dangerous? is it ischemia?) but is in fact several steps removed from them.  Note that this is a very low risk group, as were the 568 patients in the authors’ previous study (Ann Emerg Med March 2009;53:295).  In both groups (which may overlap) there were no myocardial infactions or cardiovascular deaths at 30 days. Note also that previous studies have not demonstrated any clinical benefit from this protocol, but have demonstrated that patients who receive coronary CTA have increased incidence of subsequent interventions such as angiography. And there is of course concern about the effects of radiation from coronary CTA.

Conceptually, there are several additional problems with using coronary CTA to evaluate cocaine-associated chest pain (CACP).  First, since some CACP is associated with coronary spasm without stenosis, an anatomic finding of clean coronaries certainly does not rule out ischemic etiology.  In these cases, continued use of cocaine will likely result in recurrent ischemia.  Second, in this situation, it seems to me that demonstrating lack of anatomic pathology would  send a message that there is no risk in continued use of cocaine.

Finally, two comments about the editing of this article.  An accompanying editorial by Christian Tomaszewski states that : “Before we adopt this [coronary CTA] as standard of care, we need more studies.” This “more studies” approach is, in my opinion, a cop-out.  Given the multiple problems with the test, I doubt there will never be a study large enough to establish a benefit which — most likely — does not exist.  Also, the article carries a statement that “The authors have no potential financial conflicts of interest to report.” Really? Many of these same authors were on the similar Annals of Emergency Medicine study from March 2009 — which also used a Siemans scanner.  That article disclosed that several of the authors had received research funding and speaking fees from Siemans, and/or are on the company’s corporate board. The Journal of Medical Toxicology should have mentioned this.

Comments are closed.