Μελέτη βιωσιμότητας του μυοκαρδίου σε ασθενείς με πρόσφατο Q-έμφραγμα μυοκαρδίου και ανασπάσεις του διαστήματος ST στις σύστοιχες απαγωγές κατά την δοκιμασία κοπώσεως

Abstract

Objectives: The aim of this prospective study was to investigate whether ST segment elevation and T wave normalization in Q-wave leads on pre-discharge exercise electrocardiogram (ECG) can contribute to patient management after recent myocardial infarction (MI) Background: The clinical relevance of these exercise ECG changes remains controversial despite accumulating evidence of their association with myocardial viability as well as functional recovery after revascularization. Since patient selection may explain the discordant results across the studies, the value of these ST/T abnormalities in the thrombolytic era should be better defined. Methods: One-hundred one patients, aged 58+11 years, with a recent, first, uncomplicated Q-wave MI (56% anterior, 57% thrombolyzed, ejection fraction 43+7%) underwent predischarge, submaximal treadmill testing followed, in the absence of severe ischemia, by dobutamine stress echocardiography, thallium-201 single photon emission computed tomography and coronary angiography. Results: Patients with, as compared with those without ST elevation at peak exercise had more severe infarctions (peak creatine kinase 2351+1465 versus 1671+1132 U/L, p<0.05) and more extensively impaired left ventricular contractility due to scar tissue as based on the number of segments with scar on echocardiography (p<0.05) or scintigraphy (p<0.01). However, the incidence of myocardial viability and ischemia was not different between the two groups. Results were similar for ST elevation at low level exercise. Anterior infarction location and at least three scarred segments on dobutamine stress echocardiography were among the independent predictors of ST elevation at peak ergometric exercise. T wave normalization was similarly inaccurate in identifying viability or ischemia. Over long-term follow-up of 31+13 months, the event rate was low ( 8 % for death or nonfatal MI) and did not differ between groups with or without these exercise-induced ST/T wave changes. Conclusions: In patients after acute, Q-wave MI without severe ischemia according to clinical and standard ECG criteria, exercise-induced ST elevation is associated with larger infarctions. The contribution of these ST/T changes to identify patients with myocardial viability or ischemia and for risk stratification is poor. In-hospital management of these patients based on routine clinical practice is sufficient for selection of a population with a relatively low long-term risk.