CT Angiography: A New Crossroad?

Cardiac computed tomography (CT) has evolved rapidly over the last 20 years. Not long ago, the only proven utility of cardiac CT was the “mammogram of the heart,” allowing risk stratification and identification of early atherosclerosis.¹ As the technology evolved, noninvasive angiography became established, and the diagnostic accuracy of this tool became established.² Soon to follow was the use of three-dimensional reconstructions to facilitate electrophysiologic procedures such as atrial fibrillation ablation and biventricular lead placement.³ In this issue of the Journal of Invasive Cardiology, Ehara et al⁴ demonstrate a new potential utility of cardiac CT to facilitate advanced interventional procedures such as chronic total occlusions. Some would argue that multidetector CT (MDCT) only adds radiation and contrast load to patients who have a high probability of disease, and thus would not benefit this population. The authors demonstrated that MDCT can provide simple and accurate assessment of anatomy in patients who have chronic total occlusions. In this study, bending, shrinkage and severe calcification were significant predictors for wiring success. While there was no formal quantification of benefit of the CT, clearly MDCT provided some practical assessment that predicted outcomes in percutaneous interventions. Formal cost analysis needs to be done, but it appears that MDCT will assist clinicians to better select patients and have a higher rate of success with these difficult patients. Certainly, this study has some very practical applications, for interpreters of cardiac CT computed tomography should have a better understanding of what is important to report when CT angiography reveals chronic total occlusions, and what anatomy is more amenable to success with wiring. Rather than dismissing the possibility of successful PCI, one can use these simple markers to determine the likelihood of procedural success and the utility (or futility) of attempting PCI in these patients. Clearly, validation studies need to be done, but this provides a nice backdrop for evaluations. The true utility and applicability of MDCT to be performed after coronary angiography needs further cost and risk:benefit analysis, but several articles have demonstrated significant potential uses of this technology in accordance with percutaneous coronary intervention.⁵ It is clear that the evolution of cardiac CT is ongoing, and we are still at the rapid stages of development in defining the true and best clinical applications of this test. Ehara and colleagues have opened another door, and hopefully, randomized trials will continue to follow, demonstrating the true clinical utility of this tool.

References

1. Budoff MJ, Achenbach S, Blumenthal RS, et al. Assessment of coronary artery disease by cardiac computed tomography, A scientific statement from the American Heart Association Committee on Cardiovascular Imaging and Intervention, Council on Cardiovascular Radiology and Intervention, and Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation 2006;114:1761–1791. 2. Budoff MJ, Dowe D, Jollis JG, et al. Diagnostic performance of 64-detector row coronary computed tomographic angiography of individuals undergoing invasive coronary prospective multicenter ACCURACY (Assessment by Coronary Computed Individuals without Known Coronary Artery Disease: Results from the Tomographic Angiography for Evaluation of Coronary Artery Stenosis in Angiography) trial. J Am Coll Cardiol 2008;52:1724–1732. 3. Shinbane JS, Girsky MJ, Chau A, Mao S, Budoff MJ. Three-dimensional computed tomography imaging of left atrial anatomy for atrial fibrillation ablation. Clin Cardiol 2005;28:100. 4. Ehara M, Terashima M, Kawai M, et al. Impact of multislice computed tomography to estimate difficulty in wire crossing in percutaneous coronary intervention for chronic total occlusion. J Invasive Cardiol 2009:21:575–582. 5. Hecht HS. Applications of multislice coronary computed tomographic angiography to percutaneous coronary intervention: How did we ever do without it? Catheter Cardiovasc Interv 2008;71:490–503.