Tuesday, October 31, 2006

ER CT Scan Screening for Heart Attack

Will CT Scan's be the next great thing to "rule out" a heart attack in the ER? It seems some think so.

In a pre-publication article from Circulation, researchers from the Massachusetts General Hospital tested the sensitivity and specificity of multi-detector CT scanning (MDCT) for the presence of calcium in the coronary arteries (or narrowing) as a surrogate for the presence of heart disease and found excellent sensitivity (100%) and fair specificity (42-82%) at predicting if a patient had an acute coronary syndrome (ACS). While the results seem promising, there were important limitations to the application of this technology to a large ER population. Of 306 patients, only 123 were eligible to consent. Why? Because the study excluded people with heart rhythm abnormalities (this effects the quality of the CT scans obtained), their kidney function was too abnormal (creatinine > 1.3) or they were allergic to iodine (renotoxic iodine contrast is used for this study. Others reasons cited for not performing the scans was because some patients ruled in for heart problems with more conventional tests or they were immediately discharged.

Nonetheless, of those with an uncertain diagnosis, CT scanning with MDCT has a strong negative predictive power of 100% (that is, if patients did not have evidence of plaque or stenosis on CT scanning, they were not likely to have disease), but a positive predictive value of 23% (presence of plaque did not mean the person had an acute coronary event very well.) In appropriately selected patients, this should add to our ability to avoid admission in a larger subset of patients presenting with weird chest discomfort in the Emergency Room.

The (multi-)million dollar question is this: who will pay for this scanning? Sure the patient with an uncertain chest pain diagnosis might be able to find out their fate more quickly, but broad scale use of these scans will be VERY expensive for our health care system.

There is significant pressure by government agencies to limit CT scan imaging in ER's. And as we've seen, if these scans aren't reimbursed, few people are likely to receive them.


1 comment:

Anonymous said...

This will fall into the ER doc's lap at a great time. The biggest payouts in medmal actions (reportedly) are for missed MI's. And now, there's a test that will add to our ability to risk-stratify in the ED.

And the calculus will go: I can order a very expensive test, do my best to keep my patient safe from disease, and keep my safe from the plaintiffs' bar.