Author + information
- Kiyoshi Hibi, MD∗ (, )
- Ken Kozuma, MD,
- Kazuo Kimura, MD and
- Takaaki Isshiki, MD
- ↵∗Division of Cardiology, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama 232-0024, Japan
We appreciate Dr. Dan and colleagues for their interest in our study assessing the impact of a filter-based distal protection system on angiographic and in-hospital clinical outcomes in patients at high risk for atherothrombotic embolization (1).
With regard to the absence of a difference in infarct size, we adequately discussed this point in the Discussion section of our paper. From the beginning, we focused on carefully selected patients at high risk. Attenuated plaque ≥5 mm as evaluated by intravascular ultrasound was present in only 12.4% of the patients with ST-segment elevation myocardial infarction and in even fewer patients with non–ST-segment elevation acute coronary syndrome. Hence, claiming that there is an important selection bias seems to be an artificial argument.
Dan and colleagues note that aspiration, balloon angioplasty, or both might have modified the attenuation. However, we excluded patients who required balloon dilatation before intravascular ultrasound interrogation. Moreover, a prior study revealed that the amount of attenuated plaque identified even after stent implantation (outside the stent) strongly correlated with “no reflow.” At present, no imaging modality can precisely differentiate thrombus and atherosclerotic plaque. Attenuated plaque is a pattern that can discriminate high-risk plaque for atherothrombotic embolization, and we believe that this finding is much more important than the in vivo pathological classification.
We agree that complete blinding of the analysis is not feasible, as the filter device can be seen by the analyst. However, the corrected TIMI (Thrombosis In Myocardial Infarction) frame count, which has been shown to be an objective and quantitative index of coronary blood flow (2), was also significantly reduced by distal protection, supporting the results obtained for the primary endpoint.
The use of distal protection is currently not common during percutaneous coronary intervention worldwide. Our pre-specified subgroups analyses showed that the incidence of no reflow was reduced by 69% in patients with baseline TIMI flow grades of 0 and 1. This subset of patients should be interrogated using intravascular ultrasound before balloon dilatation to identify patients at high risk for distal embolism. Previous trials have shown that a baseline TIMI flow grade of 0 or 1 was present in 68.8% of patients with ST-segment elevation myocardial infarction, which was related to a higher incidence of no reflow after percutaneous coronary intervention and higher 1-year mortality (3). Randomized studies adequately powered for the clinical endpoints are needed to fully elucidate the clinical significance of distal protection devices in carefully selected patients at high risk for distal embolism.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation
- Hibi K.,
- Kozuma K.,
- Sonoda S.,
- et al.
- Gibson C.M.,
- Murphy S.A.,
- Rizzo M.J.,
- et al.,
- for the Thrombolysis In Myocardial Infarction (TIMI) Study Group