¿Es útil la determinación de daño miocárdico en la ecocardiografía de estrés con dobutamina para el diagnóstico y pronóstico de la cardiopatía isquémica?

Abstract

The value of pharmacological stress echocardiography using dobutamine (EDOB) in the diagnosis and prognosis of ischemic heart disease in its diverse forms of presentation has been extensively demonstrated in the medical literature. Effort or pharmacological stress techniques combined with effort or resting cardiac radionuclide perfusion scans are the traditional imaging techniques used for the detection of residual ischemia in the risk stratification of the coronary syndrome. In patients with unstable angina, the high prognostic value of the exercise stress test with thallium-201 and technetium99m-sestamibi radionuclide perfusion scanning has been demonstrated. 1 Likewise, radionuclide scanning with thallium-201 combined with dipyridamole has been shown to be safe when performed soon after myocardial infarction, and useful for predicting cardiac events during follow-up. 2 The exercise stress test combined with the radionuclide perfusion scan using technetium-99m-sestamibi or the pharmacological test with dipyridamole and the same radionuclide marker can detect residual ischemia when performed soon after myocardial infarction, as well as predict cardiac events during follow-up in the first year. 3 The prognostic value of the pharmacological stress test with dobutamine in combination with Tc-sestamibi radionuclide scans has also been evaluated in large groups of patients with chest pain. EDOB is a technique that has been much used in echocardiography laboratories and its usefulness has been evaluated extensively in populations with a suspected or known diagnosis of coronary artery disease. In the last decade, the routine use of stress echocardiography has lead to the application of this technique in the risk stratification of patients with acute coronary syndromes. Preliminary studies have already demonstrated the usefulness of bidimensional echocardiography in evaluating the prognosis of patients with unstable angina, disclosing that the presence or exacerbation of segmental motility anomalies is associated with a greater incidence of cardiac events. 4 Nevertheless, its use in patients with unstable angina has not been studied much. In our center we performed EDOB on 122 patients with unstable angina and low-to-intermediate risk who had been stabilized with medical treatment 48 h after hospital admission. 5 The one-year survival rate without cardiac events (unstable angina, infarction, or cardiac death) was significantly better in patients who had a negative test result for ischemia, even after considering that 78% of the patients were taking betablockers and only 25% of the patients reached submaximum heart rate. The divergence between the two groups was already apparent in the first months after hospital discharge and persisted throughout the 2-year follow-up period. The positive result of EDOB was an independent prognostic factor for events during follow-up and, along with left ventricular function, the most powerful prognostic factor. As is well-known, EDOB also has been shown to be very useful in the study of myocardial viability, with a good sensitivity and greater specificity than other imaging techniques. 6 For that reason, it is often used in conjunction with radionuclide techniques to obtain maximum sensitivity and specificity from the combined techniques. Likewise, it is used to stratify risk in patients who will undergo non-coronary surgery. Nevertheless, in routine practice, the maximum exercise test limited by symptoms, with electrocardiographic control of ischemia, continues to be the preferred complementary test for the diagnosis of ischemic heart disease because it is easily performed