The relative hazards for single- and double-vessel obstructive CAD were not significantly different for men vs. women. However, women with three-vessel disease had a 4.2-fold increased mortality risk, significantly greater than the 3.3-fold risk associated with triple-vessel disease in men.
In another CONFIRM analysis, this one involving roughly 8,100 patients with an average pretest likelihood of obstructive CAD of 50% by the widely used Diamond Forrester clinical risk score, investigators found that the actual prevalence of obstructive CAD on CTA was only 18%. The take-home lesson here is that cardiologists severely overestimate the likelihood of significant disease when they rely on clinical risk scores that were developed in an earlier era, Dr. Min emphasized.
Another CONFIRM analysis involved 15,223 patients, 7.2% of whom underwent coronary revascularization following CTA. Among the subgroup with high-risk CAD as defined by the Duke severity categorization criteria – for example, three vessels having moderate stenoses or two with severe stenoses – the mortality rate during an average 2.3 years of follow-up was 2.3% in those who were revascularized, significantly better than the 5.3% rate with medical management.
Dr. James Min
Thus, it appears that using CTA to identify patients with high-risk CAD results in a therapeutic benefit when such patients undergo revascularization, according to Dr. Min. In contrast, in patients with CTA findings indicative of non–high-risk CAD, mortality rates weren’t significantly different between those who had revascularization and those who had medical management only.
CONFIRM has also showed that CTA reduces the need for invasive coronary angiography. Patients with a normal CTA had a 3-year rate of invasive coronary angiography of 2.5%, and a 0.3% revascularization rate. These rates rose in graded fashion to a 44% invasive angiography rate and a 28% revascularization rate in patients with obstructive single-vessel disease on CTA; a 53% invasive coronary angiography rate and 44% revascularization for those identified as having obstructive two-vessel disease; and a 69% coronary angiography rate and 67% revascularization among patients found on CTA to have obstructive three-vessel or left anterior descending disease.
Dr. Min said that at present there is no evidence-based role for CTA in the evaluation of patients without chest pain or other symptoms suggestive of CAD. And there are better prognostic tests for those with known CAD, he added.
"I must say, looking at it from the outside, it’s really breathtaking how fast the data have grown over the last few years for CT angiography," Dr. Udelson commented. "You in the CT world have, in just a few short years, developed enormous databases it took those of us in nuclear imaging much longer to develop, and you can look at things nuclear can’t, like nonobstructive plaque, where the outcome is different than in people with normal coronary arteries."
Dr. Min has received research grants and is on the speakers bureau for GE Healthcare.