PROMISE Compares CT Scans and Functional Tests to Diagnose Heart Disease

March 14, 2015—The American College of Cardiology (ACC) announced that findings from the PROMISE trial were presented by lead investigator Pamela Douglas, MD, during a late-breaking trials session at the ACC’s 64^th annual scientific session in San Diego, California. Dr. Douglas is the Ursula Geller Professorship for Research in Cardiovascular Diseases at Duke University in Durham, North Carolina.

According to the ACC announcement, the PROMISE trial is the first randomized controlled trial to compare clinical outcomes in patients receiving functional stress testing or computed tomographic (CT) angiography to check for signs of cardiovascular disease. The investigators also advised that PROMISE provides the first data to inform clinical guidelines on the use of these tests.

The investigators found that both diagnostic modes are excellent options for avoiding serious adverse heart problems but CT scans appear to be a slightly better option to avoid subsequent tests and procedures, or to avoid radiation exposure. The investigators plan to further investigate outcomes for different subgroups of patients to determine whether different groups might benefit from different testing approaches.

“A Randomized Comparison of Anatomic versus Functional Diagnostic Testing Strategies in Symptomatic Patients with Suspected Coronary Artery Disease: The Results from the PROMISE trial” was simultaneously published online in The New England Journal of Medicine.

The PROMISE investigators also analyzed the financial implications of the data in terms of medical costs and reimbursements. These findings are being presented in separate Late-Breaking Trials session at the ACC meeting.

PROMISE is listed on the US National Institutes of Health website, www.clinicaltrials.gov, with identifier NCT01174550. The study was funded by the National Heart, Lung, and Blood Institute of the US National Institutes of Health.

As summarized by ACC, the PROMISE study was composed of 10,003 patients enrolled at 193 health centers in the United States and Canada. The patients had no previous diagnosis of coronary artery disease but had new symptoms that made physicians suspect they might have heart disease. Approximately all of the patients had at least one cardiovascular risk factor such as high blood pressure, diabetes, or a history of smoking.

In the study, half of the patients were randomized to receive a cardiac CT scan and half to receive a functional test—an exercise electrocardiogram, stress echocardiography, or nuclear stress test.

The study showed no differences between patients receiving a heart CT scan and those receiving functional heart tests in terms of the study’s primary endpoint, a composite rate of death, heart attack, major procedural complications, or hospitalization for chest pain. At least one of these outcomes occurred in approximately 3% of patients in both groups during more than 2 years of follow-up.  

However, some secondary endpoints, including the level of radiation exposure and the rate of subsequent procedures that did not reveal significant heart disease, favored computed tomographic angiography.

According to the investigators, these results are important because current clinical guidelines leave the selection of tests for patients reporting symptoms such as chest pain or shortness of breath—which constitutes at least 4 million patients in the United States each year—largely up to physician and patient preference.

Dr. Douglas commented, “Until this study, we have essentially been guessing on decisions about which initial test to use for this huge population of patients who need evaluation for cardiovascular symptoms. Our study shows that the prognostic outcomes are excellent and are similar regardless of what type of test you use, but there are some indications that computed tomographic angiography might be the safer test with fewer catheterizations without obstructive disease and lower radiation exposure when compared to nuclear testing.”

The study also offers a reflection of current medical practice. Dr. Douglas stated, “Unlike most trials where medical care is very tightly controlled, this study was designed to represent real-world care. The health centers that collected the data were responsible for interpreting the tests and doing appropriate patient follow-up. Because this was such a community-based, real-world setting, the study really tells us a lot about clinical practice and how patients are being cared for in the United States now.”

The 3% rate of death, heart attack, major procedural complications, or hospitalization for chest pain seen in both groups was lower than expected, especially because most study patients had two or more significant heart disease risk factors, were middle aged or older, and symptomatic.

The relative benefit of CT angiography compared to functional testing was consistent across different patient subgroups as defined by age, gender, race and cardiovascular risk factors. Although there was a significantly lower rate of death and nonfatal heart attacks after 1 year of follow-up in patients receiving a heart CT scan, for reasons that are unclear, this difference was not sustained in the second year, observed the investigators.

Dr. Douglas noted, “The event rate in itself is intriguing, because no previous studies have closely tracked and adjudicated the rate of adverse events in this patient population. These outcomes are so good given widespread use of medications like statins and aspirin. It does raise the question of whether we can identify a group of people who actually do not need to be tested.”

After the initial noninvasive test, approximately 10% of study patients underwent at least one cardiac catheterization procedure. The rates of patients undergoing catheterization that failed to identify substantial narrowing were significantly higher in the patients receiving functional testing, at 4.3%, compared to 3.4% in the patients who had received a CT scan. In addition, at 3 months patients receiving heart scans received significantly lower radiation exposure than patients who were given a nuclear stress test as their first diagnostic test.