[Exercise test after acute myocardial infarction: on medical therapy?]

Given the great relevance of beta-blockers after myocardial infarction, we focused our attention on this therapy, considering also the difficulty of its management: it takes a long time to up titrate as well as to wash out. Other anti-ischemic therapies, i.e. nitroderivatives and calcium-antagonists, are easier to manage and there is less need of precise schedules. Our belief is that predischarge exercise testing should be performed on beta-blocker therapy, since we deem unadvisable to interrupt this treatment in the early phase of the postinfarction clinical course, and the reasons are detailed in the text. After myocardial infarction, beta-blockers may reduce the sensitivity of predischarge exercise testing for the diagnosis of inducible ischemia; however, their interference does not seem to affect negatively the prognostic stratification of the test, also in the "thrombolytic era". This may be true since beta-blockers hide, but also cure, those forms of inducible ischemia of lower clinical importance, and only inducible ischemia occurring in spite of such therapy might be dangerous and should be treated with myocardial revascularization. Patients receiving thrombolytic treatment are a selected minority at lower clinical risk; it is necessary to emphasize that predischarge exercise testing is more frequently positive in these patients, probably because of the presence of residual stenosis of the infarct-related vessel that may often have a trivial relevance. The test has a lower negative predictive value in these patients, mainly for the higher incidence of reinfarction and ischemic events related to plaque instability, events that none of the provocative tests can predict accurately.