Cardiac CT with Somatom Definition Image source: Siemens Healthcare

DENVER—“Anatomy or ischemia: Will either one of these add to better outcomes?” asked James E. Udelson, MD, chief of the division of cardiology and director of nuclear cardiology laboratory at the Tufts Medical Center in Boston, during a presentation Sept. 9 at this year's American Society of Nuclear Cardiology (ASNC) scientific sessions.

According to Udelson, numerous studies have outlined the diagnostic and prognostic value for both ischemia and anatomy. While Udelson said that there is a clear-cut benefit to nuclear imaging, the same cannot yet be said for coronary CT angiography (CCTA). However, results of the CONFIRM data registry that enrolled nearly 23,000 patients helped move the claim toward CT forward.

“In essence, both pieces of information, anatomy and ischemia, should be better than either one alone,” Udelson offered. He added, “CT angiography data is clearly evolving and it is now possible to image coronary anatomy noninvasively with great accuracy.”

Funded by the National Heart, Lung, and Blood Institute, the PROMISE (PROspective Multicenter Imaging Study for Evaluation of Chest Pain) trial, headed by Pamela Douglas, MD, a professor at the Duke University Medical School in Durham, N.C., will look to determine whether an initial non-invasive anatomic imaging strategy with CCTA will improve outcomes compared to functional testing strategies alone in patients with possible coronary artery disease.

PROMISE enrolled nearly 10,000 patients who were randomized to undergo an anatomic strategy (64-slice CTA) or a functional strategy (pharmalogical stress imaging or exercise stress ECG).

The time to first event was used as the study’s primary outcome. PROMISE investigators want to determine whether an initial strategy of CTA will improve outcomes, Udelson said. Similar ongoing trials like RESCUE and ISCHEMIA are also studying the effects and outcomes of CCTA.

However, during his presentation, Udelson addressed whether PROMSE will resolve these types of questions. In 2014, physicians will have to start making imaging and treatment decisions based on global payments. “Physicians will be accountable for and incentivized by the bottom line of the enterprise, as well as quality and outcomes,” he offered.

While Udelson noted that “clinical trials rarely provide us with a big winner or big loser,” he said that he hopes that PROMISE will provide enough information to concur that high-risk patients will perform well with functional imaging.

“Both approaches identify CAD with reasonable accuracy [functional/CTA],” Udelson offered, and "both tests can identify high risk subsets; however, currently, ischemia data are more mature.”

Udelson concluded that robust data will show CCTA to more routinely identify patient angiography subsets who would most benefit from revascularization.

“These data create equipoise, and this really sets the stage for these large clinical trials,” he concluded.