Coronary CT angiography is reliable for ruling out coronary artery disease (CAD) in patients scheduled for cardiac valve surgery, a meta-analysis finds.
CT angiography detected stenoses greater than 50% with a sensitivity of 93% (95% CI 86-97%), specificity of 89% (95% CI 86-91%), negative likelihood ratio of 0.07 (95% CI 0.04-0.16), and a positive likelihood ratio of 8.44 (95% CI 6.49-10.99) in the pooled analysis.
“Coronary CT angiography using currently available technology is a reliable imaging alternative to invasive angiography with an excellent sensitivity and negative likelihood ratio for the detection of significant coronary stenoses in patients undergoing cardiac valve surgery,” Maksymilian P. Opolski, MD, of Poland’s Institute of Cardiology, and colleagues concluded online in JACC: Cardiovascular Imaging.
The CT approach can “serve as a gatekeeper for invasive coronary angiography prior to cardiac valve surgery,” they suggested. “Our findings support the potential for reduction of unnecessary downstream testing and catheter-related complications and costs.”
But despite good accuracy in excluding obstructive CAD, the positive likelihood ratio of coronary CT angiography to identify significant coronary stenoses was “modest,” they acknowledged.
Invasive coronary angiography is thus needed to confirm or refute a positive CT angiography in these patients, they noted. “The presence of concomitant CAD in patients undergoing cardiac valvular surgery is related to worse clinical outcomes, and various clinical studies have suggested that combined valve and bypass surgery reduces early and late mortality. Consequently, pre-surgical assessment of CAD is essential for risk stratification and determination if concomitant coronary revascularization is indicated.”
The study was a “major step forward in better understanding which populations might be suitable for coronary CT angiography to rule out the presence of CAD,” Marc Dewey, MD, of Charité – Universitätsmedizin Berlin, and Peter Schlattmann, MD, PhD, of Germany’s Jena University Hospital, wrote in an accompanying editorial.
“However, the group of patients for whom CT angiography is applicable needs to be determined by further research since the study results, which are the basis of this meta-analysis, are fairly heterogeneous and non-specific in regards to pretest probability,” they cautioned.
The meta-analysis included 17 studies and 1,107 patients with valvular heart disease.
Compared with 16-slice systems, 64-slice (or better) detectors trended toward better specificity (90% [95% CI 86-93%] versus 86% [95% CI 80-91%]) and a higher positive likelihood ratio (9.5 [95% CI 6.4-14.3] versus 6.9 [95% CI 4.7-10.3]).
Opolski’s group concluded that a wide range of technical scanners is effective for ruling out CAD, but actually finding CAD is another story: “In contrast, the use of CT angiography with <64 detectors was inadequate for the detection of significant coronary stenoses, likely as a result of worse spatial and temporal resolution.”
They also found that, without aortic stenosis, specificity was numerically better with CT angiography (96% [95% CI 89-98%] versus 87% [95% CI 84-90%] for those with aortic stenosis) and the positive likelihood ratio was greater (21.2 [95% CI 8.0-55.7] versus 7.4 [95% CI 5.9-9.4]).
“Importantly, the ability for coronary CT angiography to detect significant coronary stenoses in patients with valvular heart disease is not universal, and was lower for patients with aortic stenosis, a finding possibly reflective of the higher prevalence of atherosclerosis,” according to Opolski’s group.
Limitations of the meta-analysis included inclusion of both retrospective and propsective studies and potential selection bias due to exclusion criteria. Additionally, not all studies provided data on the patient, vessel, and segment levels.
“Another open research question is whether CT angiography can substitute invasive coronary angiography in patients referred for transcatheter aortic valve interventions (TAVI),” wrote Dewey and Schlattmann. That population, the duo suggested, tends to be older and have distinct characteristics that make it hard to generalize the findings of the meta-analysis.
Opolski declared receiving a scholarship from the Foundation for Polish Science.
Other co-authors disclosed relationships with industry.
JACC: Cardiovascular Imaging
Opolski MP, et al “Computed tomography angiography for the detection of coronary artery stenoses in patients referred for cardiac valve surgery: sytemic review and meta-analysis” JACC Cardiovasc Imaging 2016; DOI: 10.1016/j.jcmg.2015.09.028.
JACC: Cardiovascular Imaging
Dewey M, et al “Investigating patients referred for cardiac valve surgery for the presence of coronary artery disease: is computed tomography enough?” JACC Cardiovasc Imaging 2016; DOI:10.1016/j.jcmg.2015.11.032.