CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Simone R.F.F. Pedra, MD*,
Carlos A.C. Pedra, MD,
Alexandre A. Abizaid, MD,
Sérgio L.N. Braga, MD,
Rodolfo Staico, MD,
Raul Arrieta, MD,
J. Ribamar Costa, Jr, MD,
Vinicius D. Vaz, MD,
Valmir F. Fontes, MD and
J. Eduardo R. Sousa, MD
* Instituto Dante Pazzanese de Cardiologia, Av Dr Dante Pazzanese 500, CEP 04012-180, São Paulo, Brazil (Email: sfpedra{at}hotmail.com).
We appreciate Dr. Angelini’s interest in our study (1), and we thank him for his comments. Our study was part of larger project in which left ventricular function was also evaluated late after the arterial switch operation (ASO) using rest and stress two-dimensional echocardiography. The minimum follow-up period of five years after the operation was chosen arbitrarily, and because the two-stage operation might have a deleterious impact on ventricular function, those patients managed by this approach were excluded. Although almost 300 children have been operated on for transposition of the great arteries (TGA) at our institution, only a third were candidates for the study based on the inclusion and exclusion criteria. Because of TGA the referral nature of our institution and the continental size of our country, a significant number of patients were lost to follow-up. In addition, many patients who were contacted refused to participate in the protocol because they had been doing well. This explains why only 22 patients were eventually enrolled. As such, we agree with Dr. Angelini that this may not be a representative sample of the whole series of patients. However, because the intravascular ultrasound (IVUS) findings in our study were very similar for the entire cohort (1), it is unlikely that all patients who were not enrolled had dissimilar IVUS findings.
The fact that IVUS could not be performed in two children does not mean that we only performed the technically easy cases. We simply took a safer approach; it would have been hard to justify any complications associated with technical difficulties in a symptom-free population, especially considering that the use of IVUS for coronary assessment late after the ASO for TGA is a delicate subject, as Dr. Angelini correctly pointed out in his letter.
Although the arguments presented by Dr. Angelini were very interesting, we disagree that our Figure 5A (1) represents an intramural coronary segment. Indeed, an intramural coronary artery may be occasionally found in neonates with TGA, posing technical difficulties to transfer the aortocoronary flap to the neoaorta and increasing the surgical risks (2). However, none of the patients in our series had this anatomical pattern at the operation. In addition, real-time cross-sectional IVUS imaging in that patient did not show any phasic compression or a half-moon appearance of the ostium. In fact, the ostium possessed an elliptical configuration, which had a cross-sectional area very similar to the adjacent distal coronary segment.
Acquired compression, torsion, and stretching of the proximal coronary arteries certainly occur after the ASO. In fact, these lesions are associated with early coronary events after a technically difficult operation, as shown by Legendre et al. (3). Late coronary events, albeit uncommon, are unlikely to be explained on the same grounds. In their series, Legendre et al. (3) reported a patient who had a normal coronary angiogram and eventually developed a late coronary artery obstruction, indicating that there are other mechanisms involved in late obstructions. The observation that most of the studied vessels in our series had proximal eccentric intimal thickening suggests the development of early atherosclerosis in the reimplanted coronary arteries (1), which may have a role in the genesis of late coronary events. Severe intracoronary fibrous proliferation may occur after the ASO, resulting in infarction and death (4).
At the moment, no matter what mechanism is involved, there is not enough evidence to state that these abnormalities are self-limited and do not progress with time. In fact, we would rather take a more cautious approach, highlighting the need to develop strategies to control risk factors for coronary artery disease in the late follow-up of these patients.
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References
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1. Pedra SR, Pedra CA, Abizaid AA, et al. Intracoronary ultrasound assessment late after the arterial switch operation for transposition of the great arteries J Am Coll Cardiol 2005;45:2061-2068.[Abstract/Free Full Text]2. Pasquali SK, Hasselblad V, Li JS, Kong DF, Sanders SP. Coronary artery pattern and outcome of arterial switch operation for transposition of the great arteriesa meta-analysis. Circulation 2002;106:2575-2580.[Abstract/Free Full Text] 3. Legendre A, Losay J, Touchot-Kone A, et al. Coronary events after arterial switch operation for transposition of the great arteries Circulation 2003;108(Suppl 1):II186-II190. 4. Tsuda E, Imakita M, Yagihara T, et al. Late death after arterial switch operation for transposition of the great arteries Am Heart J 1992;124:1551-1557.[CrossRef][Web of Science][Medline]
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