ORLANDO — Patients who had their coronary calcium levels imaged by CT angiography had substantially better survival than did similar patients who underwent standard management, an observational study has shown.
The findings, which involved more than 4,000 patients followed for more than 6 years, could have implications for insurance reimbursement of CT angiography, Dr. Matthew J. Budoff said at the annual scientific sessions of the American Heart Association. He hypothesized that the mortality difference between patients who underwent CT imaging and those who did not may be explained by improved compliance with therapy among patients who were able to see the extent of their calcified coronary disease.
Although several payers including United Healthcare, Aetna, Medicare, and Medicaid currently reimburse for CT angiography, the national policy of Blue Cross/Blue Shield is not to cover these examinations. The Blues' stated policy is that they will not cover new diagnostic tests until their value in improving patient outcomes is proved, Dr. Budoff said. He believes the new data mean this standard has now been met, but he acknowledged that the study was observational and not a prospective, randomized trial. Nonetheless, the size and duration of the study, as well as the striking magnitude of beneficial effect, should be persuasive, said Dr. Budoff, program director of cardiology at the Los Angeles Biomedical Research Institute at Harbor–UCLA Medical Center.
In his study, 2,538 symptomatic patients referred for assessment of possible coronary disease and evaluated by coronary CT had a 52% reduced risk of all-cause death during an average 6.7-year follow-up compared with a similar group of 1,706 patients whose work-up did not include CT angiography.
“Increased awareness of coronary artery disease severity among people undergoing CT angiography may have contributed to their survival,” Dr. Budoff said. “Probable mechanisms include increased adherence to and use of anti-atherosclerotic therapies, such as statins, angiotensin-converting enzyme inhibitors, and anti-platelet drugs” such as aspirin, he added.
Dr. Budoff shows patients in his clinic who undergo coronary CT and have coronary calcium six images of their coronary arteries that depict the calcium deposits and stenoses. “I think that this is something that leads to compliance. It's very black and white. Patients can see their plaque and stenosis and know they need treatment,” he said in an interview. Patients also receive their calcium scores.
The 4,244 symptomatic patients in the study had an average age of 58 years, and 62% did not have known coronary artery disease. The patients who underwent coronary CT and those who received standard care without coronary CT imaging were treated in the academic cardiology clinic at Harbor-UCLA.
The two groups were matched by age, gender, the time when they were first seen, and their conventional cardiac risk factors.
All patients undergoing coronary CT had the examination covered by their insurance providers; none of the patients paid for the exam out of pocket. One factor that the study did not control for was socioeconomic status. The patients who did not undergo CT angiography may have been, as a group, somewhat poorer than those who had CT examinations, Dr. Budoff said.
During an average 80-month follow-up, the all-cause mortality rate was 3% in patients who had CT examinations and 11% in those who did not, a statistically significant difference. Mortality rates began to diverge between the two groups after about 3 years, and then continued to diverge.
In a multivariate analysis that controlled for age, gender, and coronary risk factors, patients who had standard care had a fourfold higher risk of dying than did those who had CT angiography.
Dr. Budoff has served on the speakers bureau for GE, a company that markets CT equipment. None of his associates had any financial disclosures.
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