Coronary CTA is steadily gaining momentum as the initial diagnostic test in symptomatic patients with suspected coronary artery disease. Such approach has been particularly supported by the positive results of the randomized SCOT-HEART trial, wherein a significantly lower rate of the combined endpoint of cardiovascular death or non-fatal myocardial infarction during 5-year follow-up was noted in patients in whom coronary CTA was performed in addition to routine testing as compared to the routine testing alone (primarily exercise ECG). Noteworthy, the potentially beneficial effect of coronary CTA on prognosis has been attributed to visualization of the extent and vulnerability of coronary plaque, and thus guidance of preventive medical therapy. In addition, an array of other clinical trials consistently indicated significant cost savings with initial CTA strategy serving as a gatekeeper to the catheterization laboratory.

Another “big win” for coronary CTA was established by the long-awaited ISCHEMIA trial of 5,179 patients with stable coronary artery disease and moderate-to-severe ischemia. Importantly, whereas real-world stress testing did not confidently identify epicardial coronary disease, coronary CTA turned out to be indispensable to either exclude life-threatening left main disease or nonobstructive coronary stenoses (comprising approximately one third of the study population) before choosing between invasive strategy versus optimal medical therapy. As such, the traditional paradigm of sole functional stress testing prior to clinical decision making in stable angina is put into question, and opens up new “avenues” for anatomical evaluation by non-invasive CTA.

If coronary atherosclerosis is found, CTA holds promise to deliver the “holy grail” of cardiology—mainly to non-invasively visualize coronary stenoses and determine their functional relevance—rendering it a potential “one-stop-shop” for the diagnosis and management of patients with ischemic heart disease. Currently, FFR-CT using computational fluid dynamics to simulate the effect of coronary artery stenoses on downstream myocardial perfusion is one option that can be easily derived from a standard CTA study at no extra cost of radiation or acquisition. As an alternative, CT myocardial perfusion imaging can be employed. Although still at the early stage of technology, both FFR-CT and CT myocardial perfusion enhance the diagnostic accuracy of anatomic-based coronary CTA.

Beyond stenosis detection, the abundance of anatomic, morphologic, and physiological information incorporated from a single CTA study has generated considerable interest in the context of preprocedural planning for coronary revascularization. Unlike invasive coronary angiography, CTA provides 3-dimensional coverage of the entire spectrum of coronary tree, and can show atherosclerotic plaque. The potential benefits for interventional cardiologists are particularly salient in cases in which non-invasive CTA exceeds invasive angiograms (e.g., chronic total occlusions with ambiguous proximal cap or poor distal target, bifurcation lesions or coronary anomalies). In addition, the procedure itself may be facilitated by projection of 3-dimensional CTA reconstructions onto separate monitors in the catheterization laboratory with a potential for automatic alignment according to the angulation of the C-arm. Finally, the anatomic measurements of the vessel size and lesion length on CTA are already used for stent size selection in some luminary centers, and coupling the anatomic and physiological information before and after PCI may be the best solution for developing CT hybrid algorithms for virtual stenting in the foreseeable future.

I remember the prophetic words of Prof. Antonio Colombo in 2015 who claimed that “invasive coronary angiography is getting old and in the near future will only be utilized in selected circumstances, where coronary CTA is likely to underperform”. Yet, with the announcement of the results of SCOT-HEART and ISCHEMIA trials (not to mention the continuous shift towards non-invasive evaluation of coronaries by means of CTA), this statement holds true even more. Consequently, whereas the absolute number of PCI should further decline, the rate of complex high-risk indicated procedures (CHIP) including chronic total occlusions, left main, atherectomy, and mechanical circulatory support-PCI should increase.