Marlene Busko

July 17, 2013

MONTREAL, QC — In a study of young individuals seen at a military center who had chest pain but were at low to moderate risk of having an MI, the percentage of patients sent for invasive coronary angiography (ICA) dropped by 62% after cardiac computed tomography (CT) became available[1].

By using cardiac CT to determine who would proceed to the cath lab, costs of diagnostic testing and the number of lost working days each decreased by about half.

Dr Ahmad Slim (San Antonio Military Medical Center, TX) presented these findings here in an oral abstract at the Society of Cardiovascular Computed Tomography (SCCT) 2013 Scientific Meeting .

To heartwire , Slim said that before the military center introduced cardiac CT imaging, in most cases, ICA was done for "soft" indications--that is, when guidelines only weakly recommended this test. In a similar way, an insurance provider in a nonmilitary setting might require ICA for this type of indication to avoid potential litigation and reassure a patient, he noted.

However, this study shows that "if you adopt the same concept [using CT angiography as a 'gatekeeper' to decide which patients should proceed to ICA], you can save a lot of money in the long run," according to Slim.

It is very costly to evacuate young individuals in the combat zone who present with chest pain, he told the audience.

Military Medical Chart Review

His research team performed a retrospective chart review in a single US military medical center in Germany to compare ICA costs and utilization during two periods: a control period (from 2006 to 2008) when cardiac CT was not available vs a study period (2009) when cardiac CT was available.

A total of 575 relatively young subjects (mean age 44) with possible CAD were included in the study. "In this population, a big proportion of patients had an indication to progress to the cath lab that was based either on symptoms [chest pain] or an abnormal myocardial perfusion scan," Slim said.

About 15% of patients had previously presented with chest pain.

During the study, 461 patients had ICA and 114 patients had coronary CT imaging.

After coronary CT became available, the annual rate of ICA dropped by 62%.

Among patients who were being sent for ICA, those who were sent after undergoing coronary CT had a stronger indication for this procedure.

In the control period, 14% of patients referred for ICA had a class I indication, 4% had a class II indication, and 82% had a "soft" class IIb indication based on ACC/AHA guidelines, Slim said.

These were "individuals with a high-risk occupation who needed a definitive diagnosis before they went into combat," he pointed out.

On the other hand, in the study period, the pattern shifted: now 77% of referred patients had a class I indication, 2% had a class II indication, and 21% had a class IIb indication for ICA.

More patients who were being sent for ICA in the study period had an obstruction. Obstructive disease was detected in 22% of patients (91/409) in the control period vs 69% of patients (36/52) in the study period.

Costs and Lost Workdays Dropped

From before to after CT screening became available, the mean number of lost working days dropped by about half, from 6.5 days to 2.5 days. Similarly, the mean costs of diagnostic tests fell by about half, from close to $3000 to close to $1500.

Of special note, the percentage of repeat patients (who returned with chest pain) dropped from 18% in the control period to 14% in the study period--possibly because the patients were reassured by the anatomical test results--resulting in a significant saving in healthcare costs.

"So there's definite utility in the use of [CT angiography] in that population," Slim summarized. But while Slim took pains to explain the unique role CTA might play in this specific military patient group, he believes the findings would largely translate to other patient populations. For example, he and his colleagues found a similar reduction in downstream overutilization of ICA tests before CT imaging was introduced as a "gatekeeper" among patients with chest pain seen in a large, 100-bed hospital in San Antonio, although they have not formally studied this setting.

Slim has no relevant financial relationships to disclose.



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