3-D heart imaging shown to be ‘keeping its PROMISE’

Doctors ordering exams on patients who show signs of heart disease really can’t go wrong if they choose high-tech computed tomographic angiography (CTA) over time-honored stress testing.

In fact, while 3-D CTA is no better than stress testing when it comes to alerting docs that a serious heart event is looming, it’s no worse or costlier, either. And it seems to bring back fewer false positives—a precision that can preclude unnecessary cardiac catheterizations, saving risk, time and trouble for the patient along with substantial sums of money for the U.S. healthcare system.

These findings came to light in a 193-site study of 10,003 symptomatic patients with no prior diagnosis of coronary artery disease but with at least one risk factor, such as diabetes, high blood pressure or smoking.

Results of the randomized, federally funded trial—called PROMISE for Prospective Multicenter Imaging Study for Evaluation of Chest Pain—were posted online March 14 in the New England Journal of Medicine.

The study data show that, of the patients who were sent on to the cardiac cath lab, the invasive procedure performed there found no obstructive disease after all in more than half the control group (52.5%). That was the case for only 27.9% of the CTA group.

The functional exercise testing, or “stress tests,” consisted of either a standard exercise ECG test, a nuclear stress test, or stress echocardiography. Patients were randomly sent for any of those or for CTA.

The outcomes for both groups were remarkably close—and suggested good things about the state of heart care. Within two years of testing or scanning, a serious heart event, procedural complication or death occurred in only 3.3% of the CTA group and just 3% of the control group.

“Many insurers other than Medicare have balked at covering CTA, in part out of concern about clinicians using it to screen for coronary artery disease in asymptomatic patients, for which it is not indicated,” wrote Christopher Kramer, MD, director of cardiovascular imaging at University of Virginia Health System, in an editorial accompanying the NEJM article. “The lack of evidence supporting CTA in randomized trials has also been cited. PROMISE answers the bell in that regard.”

Crediting appropriate-use criteria developed by ACR and other medical societies, Kramer noted that total spending on cardiovascular imaging has decreased by nearly 30% since 2006.

Meanwhile, concerns over radiation doses with CTA have been “alleviated by the trial results,” added Kramer. “As CTA technology advances, radiation doses continue to decrease, without a decrement in diagnostic accuracy. … [T]he cardiovascular imaging field is delivering comparative effectiveness studies with results that are likely to change clinical practice. This is indeed a PROMISE kept.”

Click here for the full study and here for Kramer’s commentary.