Author + information
- Pannipa Suwannasom, MD,
- Yohei Sotomi, MD,
- Yoshinobu Onuma, MD, PhD and
- Patrick W. Serruys, MD, PhD∗ ()
- ↵∗P.O. Box 2125, 3000 CC Rotterdam, the Netherlands
We thank Drs. Caiazzo and Di Mario for their interest in our recently published article. As outlined in our paper, intravascular ultrasound (IVUS) in the ABSORB II (A Clinical Evaluation to Compare the Safety, Efficacy and Performance of ABSORB Everolimus Eluting Bioresorbable Vascular Scaffold System Against XIENCE Everolimus Eluting Coronary Stent System in the Treatment of Subjects With Ischemic Heart Disease Caused by de Novo Native Coronary Artery Lesions) trial was only documentary and the procedure was performed under angiographic guidance. We agree that the calculation of asymmetry index is somewhat difficult to apply periprocedurally due to the absence of automatic lumen detection of current IVUS consoles. The complexity of the calculation precludes eccentricity and asymmetry index from the trials with intracoronary imaging guidance (either by IVUS and OCT) as Caiazzo and colleagues commented.
Drs. Caiazzo and Di Mario remarked that periprocedural myocardial infarction has a very limited clinical relevance. Nevertheless, a large systematic review in 23,604 patients reported that periprocedural myocardial infarction was associated with an increased risk of mortality (1), which supports the clinical significance of periprocedural myocardial infarction.
We agree that the lumen eccentricity and asymmetry may be difficult to alter by post-dilation procedure only. The combination of adequate lesion modification together with post-dilation with high pressure (2) remains to be investigated.
As mentioned by Drs. Caiazzo and Di Mario the interventional community for the time being should be guided by the absolute minimal stent area MSA cutoff value of 4.5 to 5.0 mm2 instead of an asymmetry index of >0.3 due to the nature of the post-hoc analysis. However, we have also performed subgroup analysis in lesions with an MSA of ≥5 mm2 and <5 mm2, which revealed no difference between the groups (data not shown). As reported by Puricel et al. (3), the risk of scaffold thrombosis appeared to rapidly increase for a postprocedural minimal lumen diameter of <2.4 mm (for the 2.5- to 3.0-mm bioresorbable vascular scaffold) and 2.8 mm (for the 3.5-mm bioresorbable vascular scaffold). It could be concluded that the risk of scaffold thrombosis did not relate to a final lumen area, but is related to an increase of strut footprint when large scaffolds are implanted in small vessels. In addition, we would like to underline that the absolute MSA of 4.5 to 5.0 mm2 was tested as a predictor of the patency of the stent lumen, but not of device-oriented clinical events. Of course, because the data were derived from post hoc analysis, our results should be interpreted with caution and remain hypothesis generating. However, the issues of asymmetry and eccentricity are worth investigating in a prospective clinical trial. The accumulation of scientific evidence would also enhance the development of the IVUS workstation to support automatic lumen detection and calculation of eccentricity and asymmetry index in the near future.
Please note: Drs. Serruys and Onuma are members of the international advisory board of Abbott Vascular. Drs. Suwannasom and Sotomi have reported that they have no relationships relevant to the contents of this paper to disclose.
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