Letters to the Editor: Letters & Announcements
To the Editor:
Leung et al. (1) investigated the role of dobutamine stress echocardiography in patients undergoing coronary artery bypass grafting for intraoperative evaluation of left ventricular contractile reserve to predict myocardial viability. Dobutamine was administered after separation from cardiopulmonary bypass at 10 μg · kg−1 · min−1 rising doses up to 40 μg · kg−1 · min−1.
The authors identified a “normal dobutamine stress echocardiography ” response as an increase in wall thickening during the test in normal segments at baseline and a “positive test” as new or worsening regional wall motion abnormalities during dobutamine stress echocardiography. Viability was tested within 1 wk with thallium. A normal response was highly specific for viable myocardium, whereas a positive response had low sensitivity in predicting nonviable myocardium.
We would like to make the following comments:
Information about segmental contractile status before coronary artery bypass grafting is of crucial importance for distinguishing viable from nonviable segments (2,3). Only dysfunctioning segments at baseline improving or worsening during dobutamine stress echocardiography have to be considered as viable. Conversely, akinetic segments at baseline showing neither worsening nor new abnormalities should be considered nonviable (4,5), although this study possibly included these in the “normal segments.” Similarly, segments having worsening segmental function after coronary artery bypass grafting with large-dobutamine dose should be considered ischemic and thus viable (4,5), although this study included these in the “positive segments.”
In segments revascularized with arterial conduits, full restoration of coronary blood flow may need hours to days before normal myocardial perfusion is established (4). There could be serious concern about administering large-dose dobutamine in these patients.
A total of 16 segments during small-dose dobutamine stress echocardiography and 25 segments during large-dose dobutamine stress echocardiography had “positive test.” Do these segments belong to the 78 patients that completed the thallium studies?
Federico Bilotta, MD, PhD
Luciano Agati, MD
Laura Fiorani, MD
Giovanni Rosa, MD
Departments of Anesthesiology and Cardiology
Policlinico Umberto I and Ospedale S Andrea
University of Rome “La Sapienza”
1. Leung JM, Bellows WH, Pastor D. Does intraoperative evaluation of left ventricular contractile reserve predict myocardial viability? A clinical study using dobutamine stress echocardiography in patients undergoing coronary artery bypass graft surgery. Anesth Analg 2004;99:647–54.
2. Voci P, Bilotta F, Aronson S, et al. Echocardiographic analysis of dysfunctional and normal myocardial segments before and immediately after coronary artery bypass graft surgery. Anesth Analg 1992;75:213–8.
3. Voci P, Bilotta F, Caretta Q, et al. Low-dose dobutamine echocardiography predicts the early response of dysfunctioning myocardial segments to coronary artery bypass grafting. Am Heart J 1995;129:521–6.
4. Agati L, Voci P, Autore C, et al. Combined use of dobutamine echocardiography and myocardial contrast echocardiography in predicting regional dysfunctional recovery after coronary revascularization in patients with recent myocardial infarction. Eur Heart J 1997;18:771–9.
5. Agati L, Autore C, Iacoboni C, et al. The complex relation between myocardial viability and functional recovery in chronic left ventricular dysfunction. Am J Cardiol 1998;81(12A): 33G–5.