Coronary Computed Tomography Angiography

A highly detailed CT scan of the heart can safely and quickly rule out the possibility of a heart attack among many patients who come to hospital emergency rooms (ER) with chest pain, according to the results of a study that was presented by researchers from the Perelman School of Medicine at the University of Pennsylvania at the American College of Cardiology’s 61st Annual Scientific Session and published on March 26, 2012, in the New England Journal of Medicine. The multicenter randomized trial comparing Coronary Computed Tomography Angiography (CCTA) and traditional cardiac testing methods revealed that chest pain patients with negative CT scans can be discharged safely from the hospital within hours. These findings may offer a new strategy for relieving the emergency room crowding that plagues many of America’s hospitals, and could help to trim millions of dollars off the costs of care for one of the leading causes of ER visits.

A 64-slice Philips CT machine is used for CCTA examinations at Hringbraut hospital in Reykjavik, Iceland.

Chest pain is the second most common reason people go the emergency room in the United States, accounting for as many as 8 million visits each year at a cost of several billion dollars. Just 5-15% of those patients are ultimately found to be suffering from heart attacks or other serious cardiac diseases, since issues from pneumonia to indigestion to anxiety can cause the same types of symptoms. But more than half of chest pain patients are admitted to the hospital for observation or traditional evaluation such as cardiac catheterization or a stress test.

ECG is commonly used to synchronise the CT machine with a CCTA examination, for better images and lower radiation doses.

The authors studied 1,370 patients at five medical centers who were classified as low-to-intermediate risk for heart attack, meaning they had no previously identified heart disease and did not have cardiac risk factors such as diabetes or high blood pressure. They randomized patients to one of two arms: those who received a CCTA scan and those who received conventional care strategies to rule out serious blockages of the arteries supplying the heart. Of 640 patients whose CCTA was negative, revealing no clinically important coronary artery blockages, none died or suffered a heart attack within 30 days. The investigators also found that patients in the CCTA arm were more than twice as likely to be discharged directly from the emergency department to their homes (50%) than those who underwent traditional care (23%). Patients in the CCTA arm also spent significantly less time in the hospital (a median of 18 hours), compared to those in the traditional care group (25 hours). Those with negative tests had an even greater difference in the length of their hospital stay (12 vs. 25 hours). Additionally, CCTA proved to be more effective at identifying patients with coronary artery disease compared to stress testing (9% of patients had a positive test vs. 3.5%).

Beta-blockers and nitroglycerin are frequently administered at CCTA examinations, stabilising and lowering the heart rate to 60 beats per minute or less.

“CT scanning has long been used in emergency departments to learn the cause of other symptoms like abdominal pain and shortness of breath. It’s available in many hospitals around the clock, so now we can answer important questions about chest pain right away and send patients home much more quickly,” said lead author Harold Litt, MD, PhD, chief of Cardiovascular Imaging in the department or radiology. “This test allows us to get a very good look at the coronary arteries in a noninvasive way, and for the large majority of people who are shown to not have a narrowing of the arteries, it’s an excellent alternative to cardiac catheterization.”

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CCTA generates three-dimensional images of the heart and the blood vessels surrounding it. The tests, which are conducted like a standard CT scan, cost about $1,500 and allow patients who have a negative scan to be discharged from the hospital within hours, while costs for those admitted to the hospital for stress testing and monitoring typically total more than $4,000 for each patient.

– My next post will be about dual source & dual energy CT.