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Ann Thorac Surg 2002;73:1410
© 2002 The Society of Thoracic Surgeons

Invited commentary

^a Department of Thoracic Surgery, Thoraxcenter, Erasmus Medical Center Rotterdam, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands

e-mail: kappetein{at}thch.azr.nl

The incidence of severe left ventricular dysfunction secondary to chronic coronary artery disease is increasing. In coronary artery disease, flow reserve decreases in proportion to the degree of stenosis and it may lead to intermittent or chronic episodes of ischemia and, consequently, postischemic stunning. If these episodes are frequent with incomplete recovery of contractile function before the next insult, this may trigger the development of myocardial hibernation and might play a role in the development of chronic reversible left ventricular dysfunction. In the presence of viable myocardium, coronary revascularization would reduce the chronic ischemic dysfunction by restoring flow reserve and improve left ventricular function, heart failure symptoms, and prognosis. However, surgery in these patients is associated with higher morbidity and mortality. Assessment of myocardial viability, and thus a careful selection of patients who may benefit from revascularization, is necessary to offset this higher risk.

The present study points to an important aspect of whether the use of positron emission tomography (PET) scanning is cost-effective in selecting patients who may benefit from coronary artery bypass grafting, in case of severe left ventricular dysfunction. Other tests used for diagnosing hibernating myocardium are dobutamine stress echocardiography (DSE), thallium, and sestamibi single-photon emission computed tomography (SPECT). The predictive accuracy of tests for diagnosis of hibernating myocardium is not well known, may be incorrect in 15% to 30% of patients, and may vary within a center and between centers. In a metaanalysis, direct comparison revealed that the negative predictive accuracy for DSE was somewhat lower compared to nuclear techniques, whereas the positive predictive accuracy was higher. DSE underestimates the improvement in function or nuclear imaging overestimates the improvement. However, DSE is less expensive and the availability much better compared to PET scanning.

Patients in the present study have already undergone angiography to evaluate their coronary status. In terms of cost-effectiveness, it would be more rational to perform a PET scan and then to decide whether an angiography is necessary. The patients considered in this study have congestive heart failure as the most predominant symptom and not angina; otherwise, angina would have warranted revascularization. The number of life years gained for these three treatment groups, in which the main indication is congestive heart failure, is difficult to obtain and are based on only one study with a limited number of patients per treatment group. At present, there are no well-designed studies that evaluate whether optimal medical therapy by current standards (as in the third treatment group) is of benefit in hibernating myocardium.

Many studies have shown that viability assessment may provide prognostic information for morbidity and mortality. The present study underscores this and indicates that the use of a rather expensive technique, such as PET, may be cost-effective in a selected group of patients. However, there is a need for well-designed studies that reproducibly quantify the amount of hibernating myocardium, assess the accuracy of different tests, and evaluate whether optimal medical therapy or revascularization is of benefit in different clinical syndromes. These studies should also assess the cost-effectiveness of the different diagnostic and therapeutic strategies.

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kappetein, A.P. Search for Related Content PubMed Articles by Kappetein, A.P. Related Collections Coronary disease