Other side of the coin: CT has advantages over SPECT for detection of stable CAD

In a companion piece that counters an opinion that SPECT is the best modality for first-line detection of CAD, separate experts argued that CT finds sub-clinical atherosclerosis and important coronary anatomy, providing earlier diagnoses and the option to be more aggressive with treatment, according to a review published April 10 in the Journal of Nuclear Cardiology.

Ahmed Aljizeeri, MBBS, from the department of cardiology at University of Ottawa Heart Institute in Ottawa, Ontario, Canada, and colleagues drew data from a range of CT studies providing data about the technology’s value for detecting CAD.

“A modality that not only accurately diagnoses obstructive CAD but also facilitates early identification of non-obstructive CAD may be of interest because it may allow for earlier aggressive risk factor modification and primary prevention,” wrote the authors. “This is of immense importance since plaque rupture associated with acute coronary syndromes occurs most commonly in non-obstructive plaque.”

A meta-analysis of cardiac computerized tomographic angiography (CCTA) involving 45 studies and 2,045 patients determined that collectively the modality had a sensitivity of 99 percent and a specificity of 88 percent.

A European trial including 360 subjects showed respective sensitivity, specificity, and negative predictive vale (NPV) at 99 percent, 64 percent, and 97 percent.

Another international multi-center trial, CORonary artery Evaluation (CORE64), looked at the use of 64-row multidetector CT angiography in 291 patients across nine centers and found sensitivity to be 85 percent, specificity at 90 percent and NPV at 83 percent.

The assessment by coronary computed tomography angiography of individuals undergoing invasive coronary angiography trial (ACCURACY), focusing on 16-slice CCTA, indicated that across 230 patients and 16 imaging centers, CCTA had a sensitivity of 95 percent and specificity of 83 percent, as well as NPV of 99 percent.

“These studies support the notion that CCTA is particularly useful as a ‘rule-out’ strategy,” wrote the authors. “Due to its high NPV, CCTA is a highly desirable modality particularly in populations with lower rates of obstructive CAD.”

CCTA may be especially suited for newly diagnosed left ventricular systolic dysfunction and pre-procedure imaging prior to cardiac surgery, where a recent study indicated both 100 percent sensitivity and NPV for detecting CAD in 70 patients about to undergo open heart surgery.

“Thus, CCTA can be implemented to rule out significant CAD in patients with low-intermediate likelihood of CAD undergoing valve surgery,” the researchers wrote. “If normal, these patients can proceed directly to surgery without exposure to the risks of [invasive coronary angiography].”

A new area of research is developing functional CCTA that reveal the hemodynamics of anatomic coronary structures.

“Recent studies suggest that CT myocardial perfusion is feasible, provides functional information, and provides incremental diagnostic information over CCTA alone (AUC increased from 0.77 to 0.90),” wrote the authors. “This may enhance patient assessment and may prove to be especially useful in those with established CAD and suboptimal CCTA results.”

The companion piece which touted SPECT over CT can be read here.