Initial computed tomography angiography demonstrates equivalent clinical outcomes to functional testing in symptomatic patients with CAD

Initial testing for coronary artery disease (CAD) with computed tomography angiography (CTA) in symptomatic patients doesn't appear to yield better clinical outcomes than initial functional testing, a new study has found.

Investigators for PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) randomly assigned 10,003 symptomatic patients to receive initial CTA or functional testing with exercise electrocardiography, nuclear stress testing, or stress echocardiography. The study's composite primary end point over the follow-up period was death, myocardial infarction, hospitalization for unstable angina, or a major procedural complication (defined as stroke, major bleeding, renal failure, or anaphylaxis). Secondary end points at 90 days were invasive catheterization that did not show obstructive CAD and cumulative exposure to radiation. The study was published online by the New England Journal of Medicine on March 14.

A total of 10,003 patients were included in the study, 4,996 assigned to CTA and 5,007 assigned to functional testing. Mean age was 60.8 years, and 52.7% were women. Overall, 87.7% reported chest pain or dyspnea on exertion, while 12.3% reported fatigue or weakness, arm or shoulder pain, palpitations, dizziness or light-headedness, or neck or jaw pain. The median study follow-up time was 25 months (interquartile range, 18 to 34 months; maximum, 50 months), and 93.5% of patients had complete follow-up of at least 12 months.

The composite primary end point occurred in 164 CTA patients and in 151 functional testing patients (3.3% vs. 3.0%; adjusted hazard ratio, 1.04; 95% CI, 0.83 to 1.29; P=0.75). The CTA group had fewer catheterizations that showed no obstructive CAD than did the functional testing group (3.4% vs. 4.3%; P=0.02). However, catheterization within 90 days after randomization was more common in the CTA group than in the functional testing group (12.2% vs. 8.1%). Median cumulative radiation exposure per patient was lower in those receiving CTA than in those receiving functional testing; however, overall exposure was higher in the CTA group because almost a third of patients in the functional testing group had no radiation exposure.

The researchers noted that their study did not address test performance or utility and that their findings may not apply to all settings. However, they concluded that over a median of 2 years of follow-up, initial CTA was not associated with better clinical outcomes than initial functional testing in symptomatic patients with suspected CAD.

An accompanying editorial said that “no winner was declared” between CTA and functional testing and asked, “How will a tie for CTA change clinical practice?” The editorialist pointed out that some insurers have not covered CTA because evidence from randomized, controlled trials has been lacking and noted that the current trial “answers the bell in that regard.” He also wrote that the trial should ease concerns about higher radiation exposure with CTA but said comparative cost analysis studies “may be telling” because CTA usually costs less than stress imaging but more than stress electrocardiography.

The editorialist noted that the current trial had low event rates, that almost half of the events that did occur were hospitalizations for unstable angina (“the softest of the end points in the composite”), and that inclusion of a third group of patients who received medical therapy but did not undergo testing might have been helpful. The ongoing ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) may help determine whether interventions guided by a positive test result could help lower event rates, he said.