In a real-world clinical setting, the negative predictive value of 64-slice coronary CT angiography (CCTA) is very high and helpful in predicting freedom from events for up to three years, according to a study in the Aug. 15 issue of the American Journal of Cardiology. The researchers also found cost-savings benefits associated with CCTA.
Jeffrey M. Schussler, MD, from the division of cardiology at Baylor University Medical Center in Dallas, and colleagues said that CCTA is being used more often in the evaluation of patients with chest pain. The strength of this test is its high specificity and negative predictive value in exclusion of coronary artery disease (CAD). However, they noted that the use remains controversial because there are theoretical risks from radiation exposure, additional costs of the test and no long-term data to suggest that excluding CAD by use of this test results in positive patient outcomes.
In this study, 436 patients underwent a 64-slice CCTA because of chest pain thought to be anginal. The primary physician or cardiologist ordered the CCTA based on a low to intermediate pretest probability of flow-limiting CAD. A smaller subset of patients initially underwent stress testing but had equivocal findings or continued symptoms that warranted further evaluation, according to the authors.
Schussler and colleagues found that 376 patients had no significant CAD based on CCTA results. Of the 60 patients who were believed on CCTA to have flow-limiting CAD, 57 percent ended up having PCI or coronary artery bypass grafting.
The authors wrote that the remaining 43 percent of patients did not have true flow-limiting disease on coronary catheterization and were treated medically.
With follow-up of 36 months, 100 percent of those patients with minimal or no disease by CCTA were free of events or intervention, according to the researchers.
Also, Schussler and his colleagues noted that by avoiding further invasive treatments, there is a significant potential cost savings in patients who are sent for noninvasive coronary angiography rather than invasive angiography.
The investigators estimated a cost of $2,000 per CCTA and a cost of $8,000 per invasive catheterization, which they noted “tended to overestimate the cost of the noninvasive test and underestimate the cost of diagnostic angiography.” However, based on these assumptions, these groups accrued an estimated total cost of $318,225 ($5,217/patient) for the CCTA-only group and $415,225 ($24,425/patient) for the CCTA and catheterization group.
Overall, the cost difference between the direct catheterization group and the groups using CCTA was approximately $919,650 in favor of the CT groups, the researchers reported.
The authors said that their study represents a “truly real-world situation and helps demonstrate the utility of this technology in the triage of patients with chest pain. In the future, the clinical utility of CCTA and the likelihood of improved reimbursement will be dependent on its ability to confidently predict the need for further evaluation."