Local variations in coronary CTA coverage spin heads

Local Medicare carriers in all 50 states have published guidelines for outpatient coverage of coronary CT angiography. Despite a model local coverage determination developed with the help of radiology societies and organizations, local payers have opted to craft their coverage rules in a way that has resulted in widely varying technology requirements and indications. In recent months, stakeholders have scrambled to resolve differences in language that could-in a worst-case scenario-restrict payment for a specific vendor's scanner.

All local coverage determinations (LCDs) require that coronary CTA be performed on a scanner that produces thin slices of 1 mm or less. A few payers allow exams to be performed on 16-slice scanners, and others specify 32-slices and up, while most mandate 64-slice technology. It's often unclear why carriers chose certain phraseology when describing their slice technology threshold. First Coast, for example, specifies "32 slices or better," while Cigna says "32 slices per second."

This semantic hair-splitting continues with 64-slice technology. Cahaba Government Benefit Administrators, for example, limits coverage "to those [exams] done with a 64-slice machine," while Wisconsin Physicians states that the "multidetector scanner must have at least 64 slices per gantry rotation." Trailblazer Health Enterprise says that as of Jan. 1, 2008, it will "not cover CT equipment producing fewer than 64 simultaneous images."

This has caused some confusion, as more than a few people in the radiology community have suggested the phrase "64 simultaneous images" excludes the scanner manufactured by Siemens Medical Solutions. Unlike other 64-slice scanners on the market that also have 64 detectors, the Siemens model has 32 detectors, which operate in a way that allows each detector to acquire two slices of data per gantry rotation. Siemens officials have discussed the phrase in question with the medical directors at Trailblazer and report that they've been assured of reimbursement on their high-end scanner.

"It's incredible to think that these studies won't be reimbursed when 90% of the peer-reviewed data being used to validate 64-slice coronary CTA has been conducted on the Siemens scanner," said Scott Goodwin, vice president of the CT division at Siemens.

Another example, albeit more narrow in its restriction, comes from Noridian, which requires "the multidetector scanner to have collimation of 0.625 mm or less, and a rotational speed of 375 msec or less." This language absolutely excludes the scanner from Philips Medical Systems, which has a rotational speed of 420 msec. The three other CT vendors are not affected. Representatives from Philips have discussed this problem with the contractor medical directors and were assured that a change in language is forthcoming, according to Phillip Prather, director of global cardiology CT for Philips.

As of early March, the carrier listed a draft LCD for Medicare Part A coverage that requires "a rotational speed of 375 msec or less or, alternatively, at least 64 discrete detector channels." Interestingly, the Siemens scanner, which has 32 detectors, does have 64 channels. If you're confused, you're not alone.

"I've talked to many medical directors and they are totally overwhelmed by the definitions and specifications of CT systems-what's a slice, what's the difference between temporal and spatial resolution, what is rotational speed," Prather said. "The problem is we don't have any prospective clinical trials-and we can't for ethical reasons-comparing one vendor's scanner to another or even comparing different generations of the same scanner."

Payers worry that coronary CTA will be used indiscriminately, so they've each customized covered indications as well. Noridian specifically states that imagers review the scout radiograph; if the calcium score is 600 or greater, they should stop the study. The carrier also insists that when the CTA results lead to invasive catheter angiography that then is negative, it will reimburse only for the technical component of the CTA exam.

"We haven't seen this level of detail on specifications before," said Mike Becker, general manager of global reimbursement for GE Healthcare. "I understand the concerns of the payers, but no procedures are 100% effective. If radiologists or cardiologists see information on a coronary CTA that tells them they should do an additional test, that is what they should do."

Nearly all carriers make provisions for scanning patients in the emergency department. Cahaba Government Benefit Administrators, however, states that it does not expect these procedures to be performed on an emergency department patient. Wheatlands Administrative Services has a detailed algorithm for imaging patients with unstable angina and acute chest pain syndromes that includes specific troponin T levels and a threshold score for its risk formula. It also outlines an algorithm for chronic stable angina and chest pain syndromes.

"We understand why carriers feel the need to develop complex algorithms," said Robb Young, senior manager for cardiac CT at Toshiba Medical Systems. "There is very little literature available to help payers determine the best clinical use of multidetector CT. In addition, they want to keep costs at a manageable level."

In a year or so, this discussion may be moot. Most stakeholders agree that the Centers for Medicare and Medicaid Services will issue a national coverage determination for coronary CTA in 2008. At that point, local payers will have to find another procedure to quibble about. And by all accounts, that shouldn't be too difficult.