Assessment for prognosis during and after myocardial infarction. A plea for a stratified approach
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Right after the first signs and symptoms of acute myocardial infarctions the prognosis is determined by the interventions which are carried out at that time. Preservation of as much myocardial tissue is the key element. Early deobstruction and reperfusion of the myocardium at jeopardy can lead to limitation of the ultimate infarct size, improved ventricular function and a halving of the 1-year mortality. Early supportive therapy with beta-blockade and calcium antagonists may enhance this effect. Data in 533 patients randomized to either a reperfusion strategy or to conventional therapy, combined with those from the recent literature on thrombolysis and early beta-blockade, provide the basis for this point of view. Once infarction is unavoidable and in the process of completion, probably 3-4 h after onset of symptoms, only supportive therapy is recommended, which will hardly change the outcome except for interventions during clinical care such as defibrillation. In 351 other survivors of myocardial infarction the value of clinical variables, a symptom-limited bicycle stress test at discharge, radionuclide ventriculography and 24-hour ambulatory electrocardiogram was compared in predicting 1-year survival. A history of previous myocardial infarction and heart failure during the current episode proved to be the strongest clinical predictors of death. Similarly, a low ejection fraction (less than 40%) and an insufficient blood pressure rise during stress testing (less than 30 mm Hg) identified a high risk group. Stress-test-induced angina and ST depression as well as ventricular arrhythmias from 24-hour electrocardiography were less good as predictors. In these patients treatment should be individualized and may require arteriography. Patients eligible for and completing a normal bicycle stress test after myocardial infarction proved to be a low risk group, which may constitute 65% of the total, seen in tertiary referral centers and even more in community hospitals. They neither require therapy nor further investigation. A subgroup with an intermediate risk can be identified when clinical variables, stress testing and/or resting radionuclide ventriculography are abnormal. This group requires 'tailored' therapy. Therefore, after infarction recovery, we recommend a pre-discharge stress test routinely to complement the clinical evaluation, since it also provides information on physical capacity, the indication of arrhythmias and the presence of myocardial ischemia. Thus, optimal management of acute myocardial infarction requires a stratified approach, which does not require expensive testing procedures.