Author + information
- Rodrigo Fernández-Jiménez, MD,
- Valentin Fuster, MD, PhD and
- Borja Ibáñez, MD, PhD∗ ()
- ↵∗Myocardial Pathophysiology Program, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Melchor Fernández Almagro, 3. Madrid 28029, Spain
We read with great interest the letter from Dr. Zhang and colleagues commenting on our recently published work (1). Noninvasive evaluation of myocardial edema has become possible with the development of T2-weighted and lately T2-mapping cardiac magnetic resonance sequences able to detect changes in tissue water content (2,3). Interestingly, although edema is defined as an abnormal water accumulation within a tissue, it is well known that T2 relaxation properties of myocardium are affected by other factors besides water content such as hemorrhage or microvascular obstruction, among others (4). Evaluation of tissue water content by a reference standard is therefore necessary for detecting, quantifying, and tracking the real post-myocardial infarction edema reaction. We respectfully disagree with Dr. Zhang and colleagues on their comment regarding the inappropriateness to draw the conclusion from our work that the second wave is also developed by edematous reaction. Indeed, we demonstrated that T2 abnormalities and, more importantly, increased water content in the ischemic region, as measured by the gold standard desiccation technique, were ultimately as high at day 7 as that documented at early reperfusion. Definitely, the quantification of the myocardial water content by reference standards was crucial for demonstrating a consistent appearance of 2 consecutive waves of real edema during the first week after ischemia/reperfusion in our experimental study.
Dr. Zhang and colleagues point out that salvageable and infarct regions might follow disparate edema evolution patterns. From the cardiac magnetic resonance point of view, we agree that placing a region of interest in the full thickness of the left ventricular wall is troublesome as it will contain different myocardial states. However, the identification of “clean” regions clearly outside hemorrhage/microvascular obstruction areas may be extremely difficult and, more importantly, may be subjected to a big source of bias. The quantification of water content by reference standard in such small regions would be even more difficult to perform as this procedure needs to be done in a rapid and careful manner, avoiding tissue manipulation as much as possible. We tend to disagree with the idea that edematous and infarcted zones are equivalent to salvageable and hemorrhagic areas, respectively, as suggested by Dr. Zhang and colleagues. In any case, we believe that the possibility of including different myocardial states had little effect on the results reported in our work given that transmural extent of infarction was >80% in all evaluated segments containing the regions of interest, and the observed parallel course of T2 relaxation times and water content.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose. Derek Yellon, MD, served as Guest Editor for this paper.
- American College of Cardiology Foundation
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