CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Ren Kawaguchi, MD*
* Division of Cardiology, Gunma Prefectural Cardiovascular Center, 3-12 Kameizumi-Machi, Maebashi Gunma 371-0004, Japan (Email: kawaguchi.r{at}cvc.pref.gunma.jp).
We appreciate the interest in our recent study (1) by Dr. Porto and colleagues. Myocardial blush grade (MBG) and early ST-segment resolution are well-known parameters used for describing the effectiveness of myocardial reperfusion, which is an independent predictor of long-term mortality (2). However, the aim of our study was to investigate distal embolization that occurs immediately after stent implantation: in other words, distal embolization induced by stent implantation. Although stent-induced distal embolization is one of the causes of low blush grade or early ST-segment resolution, it is not the only cause—several factors such as vasoconstriction, additional pharmacologic therapy, and time interval after stent implantation may also affect the outcome of these parameters. Because we were not investigating final coronary flow and prognosis, we believed that we did not need to consider the relationship between ST-segment re-elevation (STR) and MBG or early ST-segment resolution. Thus far, we have not come across parameters specific to estimating the extent of stent-induced distal embolization, and certainly, as we mentioned in the limitations section, we need to validate our measurements in a different cohort to see how the predictive algorithm correlates with STR. However, STR during percutaneous coronary intervention is recognized as a predictor of the no-reflow phenomenon (3,4). In the no-reflow cases, distal embolization of the plaque or thrombus from the lesion site is a likely mechanism (5,6). Therefore, distal embolization of the plaque or thrombus from the lesion site induced by stent deployment is the probable cause of STR. Based on these data, we believe that STR occurring immediately after stent implantation reflects distal embolization induced by stent implantation.
We had mentioned in the limitations section about the presence of residual luminal thrombus and the ability of the 20-MHz intravascular ultrasound catheter to assess the plaque component. Moreover, we did not have any cases with side branch occlusion in the 11 STR cases, and it should have been included in the exclusion criteria of our study.
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References
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Related Article
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Plaque Burden, Intravascular Ultrasound, and Distal Embolization Phenomenon
- Italo Porto, Luca Testa, and Adrian P. Banning
J. Am. Coll. Cardiol. 2008 51: 1323-1324.
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