Exercise testing after myocardial infarction: with or without therapy? How does thrombolysis affects its predictivity?

In the text we focused our attention on beta-blocker therapy, considering the great importance of these drugs in the treatment of myocardial infarction, also in the early phase of the postinfarction clinical course. Moreover, as for other anti-ischemic therapies--i.e. nitrodrivatives and calcium-antagonists--the management of this therapy is more difficult, because it takes time to up titrate and to wash out. In our opinion, it's unadvisable to interrupt this treatment in the early phase of the postinfarction course, and it's necessary to perform predischarge exercise testing on beta-blocker therapy; and we explain all the reasons in the text. Even if these drugs may reduce the diagnostic sensitivity for inducible ischemia of the predischarge exercise testing, their effect does not seem to modify negatively the prognostic accuracy of the provocative test, also in the "trombolytic era". In fact, beta-blockers hide but, also, cure inducible ischemia characterized by a low clinical risk; the forms of inducible ischemia that occur also with this therapy are probably dangerous and need myocardial revascularization. It's important to emphasize that predischarge exercise testing is more frequently positive in the patients treated with thrombolytic therapy, a subgroup at lower clinical risk. This finding is probably due to the presence of residual stenosis in the infarct-related vessel. The higher incidence of reinfarction and ischemic events related to plaque instability is the main cause of the lower negative predictive value of the test in these patients; in fact, none of the provocative tests can predict accurately these events.