Author + information
- Maksymilian P. Opolski, MD∗ (, )
- Adam D. Staruch, MD and
- Damini Dey, PhD
- ↵∗Department of Interventional Cardiology and Angiology, Institute of Cardiology, Alpejska 42, Warsaw 04628, Poland
We read with interest the paper by Choi et al. (1) regarding noninvasive discrimination of coronary chronic total occlusion (CTO) and subtotal occlusion (STO) by coronary computed tomography angiography (CTA). We recognize the potential clinical relevance of the noninvasive differentiation between these 2 entities because CTO usually involves a worse prognosis and more technical challenges in recanalization (2). However, we have some concerns regarding the methodological approach used in this study.
First, in the paper by Choi et al. (1), patients with a diagnosis of complete absence of luminal enhancement on coronary CTA (irrespective of the length of the occluded segment reaching up to 30 mm) were included. However, a previous CT study showed that lesions with an occlusion length ≥14.3 mm are very likely to represent CTO (3), whereas short interruptions of the contrast opacification constitute a major diagnostic puzzle for most of the clinicians interpreting CTA results. In this regard, the possibility of a potential selection bias with inclusion of some proportion of long and thus “straightforward” CTO lesions cannot be discounted. Consequently, this approach may artificially increase the sensitivity because there are more “true positive” cases than in a more confined subset of shorter CTO lesions with a challenging diagnosis on CTA. In our opinion, the incremental diagnostic yield of noninvasive CTA is related to the evaluation of coronary lesions with short interruption of the luminal enhancement that visually accounts for most of the diagnostic dilemmas in clinical practice.
A second aspect is the validation of the primary model for prediction of the procedural outcome of recanalization defined as successful percutaneous coronary intervention with a minimal diameter stenosis <50% and Thrombolysis In Myocardial Infarction grade flow grade 3. The disadvantage of this endpoint is that it provides a close dependence on all aspects of the percutaneous procedure (i.e., guidewire crossing, balloon pre-dilation, and stent implantation) that heavily rely on the individual operator’s skills, experience, and perseverance rather than the level of difficulty intrinsic to treating the lesions. A potential solution for this issue had already been applied in the recent CT-RECTOR (Computed Tomography Registry of Chronic Total Occlusion Revascularization) registry that defined the outcome variable as the ability to successfully cross the lesion with a guidewire within 30 min (4).
Third, the results of the study by Choi et al. should be interpreted with reference to the risk of bias regarding flow and timing. Indeed, the presence of coronary plaque is not a static phenomenon—a lesion may appear high-grade stenotic today but rather evolve into CTO tomorrow, and vice versa. In this context, the interval between coronary CTA and invasive angiography that extended up to 12 weeks in the study by Choi et al. (1) was perhaps too long. This issue is further complicated because patients with recent myocardial infarction (occurring within 90 days by the CTA time) were excluded, which, together with the delayed invasive coronary angiography, might have favored enrollment of older CTO.
These comments may be important when interpreting the results of the study by Choi et al. (1).
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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