SCOT-HEART Provides Support for Coronary CTA in Angina Management

SAN DIEGO, CA—Adding coronary CT angiography (CTA) to standard clinical care helps clarify the diagnosis of angina due to coronary heart disease, according to a study presented March 15, 2015, at the American College of Cardiology/i2 Scientific Session and published simultaneously online in The Lancet. The results suggest that this strategy changes how such patients are managed and may lead to a reduction in MI by increasing needed revascularizations.

“One in three future fatal and nonfatal coronary events occur in those who have been diagnosed as having noncardiac chest pain,” said David E. Newby, MD, PhD, of the University of Edinburgh (Edinburgh, Scotland) in his presentation. 

For the multicenter SCOT-HEART study, patients referred by their primary care physician to dedicated chest pain clinics in Scotland between November 2010 and September 2014 were randomized to standard care plus coronary CTA (n = 2,073) or standard care alone (n = 2,073). Standard care included unrestricted use of further imaging studies (ie, stress echocardiography, radionuclide or magnetic resonance myocardial perfusion imaging, and invasive coronary angiography). Mean age was 57.1 years and 56% were men. More than half of patients were smokers and had hypercholesterolemia. 

At initial assessment, most patients had typical or atypical angina with limiting symptoms and underwent exercise electrocardiography stress testing.

More Changes in Diagnosis, Treatment with Coronary CTA

The initial diagnosis was coronary heart disease in 47% and suspected angina due to coronary heart disease in 36%. 

At 6 weeks, coronary CTA resulted in reclassification of the diagnosis of coronary heart disease in 27% compared with 1% assigned to standard care and reclassification of angina due to coronary heart disease in 23% compared with 1% assigned to standard care (P < .0001 for both comparisons). There were increases in both the certainty (RR 2.56, 95% CI 2.33-2.79) and frequency (RR 1.09; 95% CI 1.02-1.17) of the diagnosis of coronary heart disease, but for the diagnosis of angina due to coronary heart disease, the certainty increased (RR 1.79; 95% CI 1.62-1.96) but the frequency nonsignificantly decreased (RR 0.93; 95% CI 0.85-1.02).

Furthermore, the changes in diagnosis resulted in changes in planned investigations in 15% of patients assigned to coronary CTA, including cancellation of 121 functional stress tests and 29 invasive coronary angiograms. Most of the cancellations were due to coronary CTA findings of normal (52%) or nonobstructive (31%) arteries. Additional coronary angiograms were scheduled in 94 patients based on coronary CTA findings. Of these, 88% were found to have obstructive disease and underwent revascularization.

Compared with standard care, coronary CTA also led to more changes in subsequent recommendations for preventive medications (18% vs 4%) and antianginal drugs (9% vs 1%; P < .0001 for both). Despite the changes, coronary CTA was not associated with an increase in coronary revascularizations compared with standard care (P = .06).

No differences were seen between treatment groups for the outcomes of improvement in angina stability (P = .22) or frequency (P= .21) or in subsequent hospital admissions for chest pain (P = .40).

At median follow up of 1.7 years, patients who underwent coronary CTA had a nonsignificant 38% reduction in coronary heart disease death and non-fatal MI compared with those in the standard care group (P = .05).

According to Dr. Newby, examining symptoms at 6 weeks may have been a bit premature given that it often took 6 weeks for angiograms to occur, followed by subsequent revascularization. 

“At 6 weeks, the Kaplan-Meier curves overlapped [for coronary CTA vs standard care],” he said. “But if you do a landmark analysis [excluding the delay time] you halve the rate of fatal and nonfatal myocardial infarction.”

Dr. Newby said it is a valid criticism to suggest that the coronary CTAs should have been done on day 1, but added that it was not possible logistically.

Taking the Guess Work Out

The reduction in events is in contrast to the PROMISE data, presented yesterday by Pamela S. Douglas, MD, of Duke University School of Medicine (Durham, NC) and, according to Dr. Newby, demonstrates that coronary CTA is “taking the guessing” out of how to proceed in this patient population.

“We are stopping tests in people that don’t have coronary disease and we are actually using tests that we need to use to prevent myocardial infarctions,” he added.

In an editorial accompanying SCOT-HEART, Dr. Douglas notes that it is encouraging that the rate of clinical events such as cardiovascular death/MI were low at 1.6% at 1.7 years, but says that “to show a difference in patient outcomes with different testing strategies in view of this excellent prognosis would need a large incremental test effect driving differences in downstream care, an extremely large study sample, prolonged follow-up, or a combination of these factors.”

Nevertheless, she says the study “provides important data regarding the effect of the addition of a new technology to usual care, and explores new methods for the theory and practice of imaging outcomes research.”

Dr. Newby added that economic evaluations of the strategy are important and will determine how it is adopted in various countries around the world.