The identification of myocardial hibernation in patients with ischemic heart failure by echocardiography and radionuclide studies.
Dobutamine echocardiography and myocardial radionuclide tomography are widely used to assess viability in patients with ischemic cardiomyopathy and left ventricular dysfunction. The main goal of viability evaluation has been the identification of reversible regional dysfunction in the attempt to identify patients in whom revascularization may determine an improvement of global left ventricular ejection fraction. In this application, echocardiographic and radionuclide techniques are used to characterize different pathophysiologic aspects of viable myocardium, ie, integrity of cell membrane and contractile reserve. This explains why the information of the 2 techniques are often divergent and why radionuclide techniques have the highest sensitivity but reduced specificity compared with echocardiography for predicting recovery of regional dysfunction. The identification of residual viable myocardium by either technique is strongly associated with adverse prognosis if the patients are not revascularized, and this substantially contributes to the decision-making process in individual patients. Although it has been assumed that prognostic advantages of revascularization are linked to an increase of ejection fraction, pathophysiologic and clinical observations challenge us with the possibility that benefits of revascularization may also ensue independently on the recovery of ejection fraction through alternative pathophysiologic mechanisms. Therefore, clinical application of viability tests should be evaluated against relevant endpoints, mainly represented by prolongation of life and improvement of life quality, and not by surrogate endpoints as represented by recovery of global ejection fraction. Future studies are needed to assess whether a more clinically oriented approach will provide a better selection of patient candidates for revascularization.
Division of Cardiology, Federico II University, Napoli, Italy.
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Perrone-Filardi
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Chiariello
D002316:Cardiotonic Agents; D004280:Dobutamine; D004452:Echocardiography; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D009204:Myocardial Revascularization; D017682:Myocardial Stunning / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D011379:Prognosis; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D016277:Ventricular Function, Left
D002316:Cardiotonic Agents; D004280:Dobutamine