CTA vs Stress Imaging: No Differences in Outcomes in Patients With Chest Pain, Says PROSPECT

Deborah Brauser

June 12, 2015

NEW YORK — Coronary computed tomography angiography (CTA) and radionuclide myocardial perfusion imaging (MPI) may not be all that different regarding outcomes in patients with chest pain, suggests new research[1].

The Prospective Randomized Outcome Trial Comparing Radionuclide Stress [MPI] and ECG-Gated CCTA (PROSPECT) of 400 middle-aged inpatients showed that 15% of those assigned to CTA after reporting acute chest pain on admission and 16% of those assigned to MPI had a cardiac catheterization within the following year. Of these, 7.5% vs 10%, respectively, did not need to undergo surgical or percutaneous revascularization (the primary outcome measure). These differences were not significantly different.

There were also no between-group differences in length of stay for initial procedures or deaths, nonfatal cardiovascular events, or rehospitalizations during roughly 40 months of follow-up. However, the CTA group had significantly less "long-term all-cause" radiation exposure (P<0.001) and said they were happier with their test (P=0.001) than the MPI group.

"We initially thought that CT would lead to fewer patients who had cardiac catheterizations that didn't lead to revascularization because the way it images is like a catheterization. But we didn't really find that," lead author Dr Jeffrey M Levsky (Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY) told heartwire from Medscape.

"We had seen so many patients who go to the cath lab who don't have a great reason for being there. So we were interested to know if there was some way to decrease that phenomenon. But it doesn't seem like the two modalities of CT and nuclear stress testing do this differently," said Levsky.

The findings were published online June 8, 2015 in the Annals of Internal Medicine.

The PROSPECT Trial

The investigators note that past studies have shown that coronary CTA for patients with chest pain is faster and more cost-effective compared with "standard triage protocols, which usually involve stress testing." However, questions remain about its effectiveness, especially because women and ethnic minorities "are underrepresented in the existing literature," the authors note.

The researchers decided to compare this diagnostic test with MPI, because the latter has been studied extensively, to see which would provide "superior selection of patients for invasive management and decrease length of stay without compromising patient safety."

In PROSPECT, which began enrollment in 2008, 200 participants were randomly assigned to undergo coronary CTA and 200 were assigned to MPI.

The mean age of the study participants was 57 years, and 63% were women. In addition, the majority were Hispanic (54%), followed by black (37%) and then Asian or white (4.5% each). All were hospitalized at a single inner-city medical center for chest pain and were considered to be at intermediate risk.

A total of 30 members of the CTA group and 32 members of the MPI group underwent catheterizations within 1 year, and 15 and 20 of these, respectively, did not have subsequent revascularization (unadjusted hazard ratio 0.77).

Small Differences

The CTA group had a median length of stay of 28.9 hours vs 30.4 hours for those undergoing MPI. During follow-up, 0.5% and 3% of the groups, respectively, died, and 4.5% of each group had a nonfatal CV event. Other outcomes that did not differ significantly between the groups included:

  • 43% vs 49%, respectively, for any rehospitalizations.

  • 25% vs 31% for cardiac rehospitalizations.

  • 63% vs 58% for visits to emergency departments for any cause.

  • 23% vs 21% for outpatient cardiology visits.

Radiation exposure differed, however, with a median of 9.6 mSv initially in the CTA group vs 27 mSv in the MPI group, and 24 mSv vs 29 mSv over the long term (P<0.001 for both comparisons). In addition, significantly more members of the CT group said their procedure was better than other diagnostic tests they had experienced (P=0.001) and indicated that they would be willing to undergo it again (P= 0.003).

Finally, 24% of each group reported at least one general adverse reaction. The most commonly reported events were headache, nausea, and dizziness. A significant difference was found in reports of chest pain, shortness of breath, or palpitations, with one member of the CTA group and 30 members of the MPI group reporting at least one of these (P<0.001).

The current study "gave parity to both examinations, which were performed at the same place in the treatment algorithm," write the investigators, reiterating that there were no significant differences found in the primary outcome. However, there might be "a small potential benefit" of initial CTA because of the decrease in radiation exposure, they add.

Levsky said that the study's take-home message is that clinicians practice noninvasive imaging of the heart differently across the country, with different preferences or needs based on availability and/or expertise. "And whether they use nuclear or CT appears to lead to pretty similar outcomes."

"Along with our findings on radiation and patient tolerability, CT is a good alternative," he said. "But it's not what some people make it out to be, that it's a blockbuster or really blows out of the water any other way to noninvasively image patients with suspected coronary disease."

The study was funded by grants from the American Heart Association and the National Center for Advancing Translational Sciences. Levsky reports receiving other grants from the American Heart Association during this study. Disclosures from the coauthors are listed in the article.

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