SCOT-HEART: CTCA as Diagnostic Aid in Coronary Heart Disease Patients With Suspected Angina
Coronary heart disease patients presenting with suspected angina may receive a more complete clinical assessment by using computed tomography coronary angiography (CTCA) in addition to the standard care for diagnosis, according to the results of the SCOT-HEART Trial presented on Sunday, March 16 as part of ACC.15 in San Diego, CA, and simultaneously published in the Lancet.
Using a randomized 1:1 protocol, the study looked at 4,146 patients with suspected angina due to coronary heart disease. Participants were between 18 and 75 years of age and received treatment at one of 12 health care centers in Scotland. Patients were equally randomized into two groups, the first of which were diagnosed using CTCA along with standard care protocol (n=2,073), in this case the Cardiovascular Risk Assessment: ASSIGN Score, with the other half (n=2,073) receiving standard care alone.
Overall results found that CTCA helped to clarify the diagnosis and enabled targeting of interventions, compared to standard care alone. All told, 25 percent of CTCA patients were given a different diagnosis after receiving the test compared to just 1 percent of patients who received standard care alone. The clarification of diagnoses resulted in two significant secondary endpoint measures. Plans for subsequent testing were altered in 15 percent of patients receiving CTCA compared with just 1 percent of patients in the control group. About 23 percent of patients receiving the CT scan had a change in treatment to correspond with the new diagnosis versus only 5 percent in the control group. There was no difference between the groups in either symptom severity at six weeks or subsequent hospitalizations.
“There have been studies showing that CT coronary angiograms can accurately detect coronary artery disease, but we wanted to move beyond that and ask whether this test is clinically relevant; that is, does it change the patient’s care and outcome?” said David E. Newby, M.D., Ph.D., British Heart Foundation professor at University of Edinburgh, and chief investigator of the SCOT-HEART trial. “What was very clear from the findings is it can help guide which test to do next, which procedures or drugs to give and ultimately help prevent heart attacks.”
Interestingly, while the use of CT scans appeared to boost the certainty of the diagnosis of angina due to coronary artery disease, results show a decrease in the overall frequency of this diagnosis. According to study investigators, “this finding suggests clinicians tend to over diagnose angina due to coronary heart disease, probably for fear of under treatment.” However, they noted that CTCA did diagnose many patients with angina due to coronary heart disease who had been misclassified in the clinic.
“This means we were able to stop unnecessary treatments in the former, which are often given over a lifetime and start new treatments in those now correctly diagnosed with coronary artery disease to prevent future problems; hence the apparent reductions in heart attack,” Newby said.
Newby and fellow investigators also noted that after just 20 months of follow-up, there appeared to be a 38 percent reduction in the number of heart attacks in patients who received CTCA compared with the control group (26 versus 42, respectively), suggesting that clarification of diagnosis and treatment plans may lower the risk of future heart attacks. However, the rate of heart attack in both groups was low and failed to reach statistical significance. Researchers caution that further follow-up data are needed before any definitive conclusions can be drawn regarding the effect of CTCA on cardiovascular outcomes. Still, they said the data suggest that CT scans significantly clarify the diagnosis and lead to more timely focused treatments, which may in turn affect cardiovascular outcomes.
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