Computed Tomography Angiograms May Reduce Rehospitalization Rates

October 10, 2007 (Seattle) — In a study of patients presenting to the emergency department (ED) with chest pain, researchers report that coronary computed tomography angiogram (CCTA) testing can significantly reduce rehospitalization rates on future visits. The study was presented here at the American College of Emergency Physicians Scientific Assembly 38th Annual Meeting.
Typically, patients with chest pain are evaluated with a test for levels of troponin, which is a biomarker for cardiac necrosis and thus an indicator of myocardial infarction. Patients may be given stress tests as well.
The researchers examined rehospitalization rates within 30 days of an initial ED visit for chest pain. The study group consisted of 253 patients considered low risk. Participants in the treatment group had no sign of acute ischemia, as evidenced by an electrocardiogram, and had a negative CCTA. These patients were compared with a control group of 513 patients who were given standard care of troponin testing and, in some cases, stress tests, and who had negative evaluations before release. Patients who were given stress tests were combined with those who were not because previous studies indicate that stress tests have no bearing on readmission rates.
Patients in the CCTA group were younger than patients in the control group (average age, 46 vs 51 years). Of the CCTA patients, 39% were men (vs 42% of control subjects) and 68% were black (vs 70% of control subjects). CCTA patients had an average of 1.2 cardiac risk factors, whereas control subjects had an average of 1.4.
Patients in the study group had a 2% rehospitalization rate (95% confidence interval [CI],0.7% - 4.8%) within 30 days of release compared with 6.5% of control group patients (95% CI, 4.6% - 9.0%) during that time. The difference between the 2 populations was 4.5% (95% CI, 1.4% - 7.3%; P = .007).
"Physicians tend to be very conservative with patients that present with chest pain, because 2% to 8% of myocardial infarctions are missed," said Anna Marie Chang, MD, a resident at the University of Pennsylvania Hospital, Philadelphia, who presented the research at a poster session here. "The high readmission rate [of controls] is a result of physicians being cautious, but it's also a measure of [comfort levels] with the results of the [troponin test]."
Others agreed that the use of the CCTA could reduce hospitalizations.
"A more definitive test early on will probably reduce hospitalizations," said Lee Garvey, MD, director of the chest pain evaluation center at the Carolinas Medical Center, Charlotte, North Carolina, who attended the conference. "The limitation is that the CCTA is really only available during daytime business hours, because it can only be read by specially trained radiologists and cardiologists. It will be awhile before there is a big enough pool of people available to do it" 24 hours a day, Dr. Garvey added.
The research is another piece of evidence in favor of CCTA, said W. Frank Peacock, MD, director of research for the Cleveland Clinic, Ohio, who attended the conference. "Everybody knows that there is a false-negative rate with stress tests. There will be a CTA false-negative rate, too, but we just don't know what it is yet."
The study was funded internally. Subsequent to this study, Siemens (the maker of the CTA scanner used) has funded other research performed by the same team.
American College of Emergency Physicians 38th Scientific Assembly: Abstract 20. Presented October 8, 2007.