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[Stress echocardiography in myocardial infarct]
1Serviço de Cardiologia, Hospital Fernando da Fonseca, Amadora/Sintra.
Insights
Stress echocardiography effectively assesses prognosis after myocardial infarction by evaluating myocardial ischemia and perfusion. A negative test indicates a good outlook, while a positive test predicts future cardiac events.
Area of Science:
- Cardiology
- Diagnostic Imaging
Background:
- Prognosis after myocardial infarction depends on necrosis extent, infarct artery status, and myocardium at risk.
- Stress echocardiography detects myocardial ischemia, indicated by regional wall motion abnormalities, as a marker of reduced perfusion.
Purpose of the Study:
- To evaluate the role of stress echocardiography in determining prognosis after myocardial infarction.
- To assess the diagnostic capabilities of dobutamine and dipyridamole stress echocardiography.
Main Methods:
- Dobutamine stress echocardiography assesses myocardial contractile reserve and viability.
- Dipyridamole stress echocardiography utilizes the 'steal effect' to reveal ischemia in stenosed coronary arteries.
Main Results:
- Stress echocardiography identifies myocardial ischemia and regional wall motion abnormalities.
- A negative stress echocardiogram has excellent negative predictive value for prognosis.
- A positive stress echocardiogram predicts an increased rate of adverse events during follow-up.
Conclusions:
- Stress echocardiography is a sensitive and specific tool for assessing prognosis in myocardial infarction patients.
- Both dobutamine and dipyridamole stress tests provide valuable prognostic information.
Abstract:
For patients with recent myocardial infarction, the main determinants of prognosis are: extent of transmural necrosis, state of the infarct-related artery and the presence and extent of myocardium at risk. The basic principle underlying the use of stress echocardiography states that myocardial ischaemia produces abnormalities of regional wall motion which are by themselves early, sensitive and specific markers of decreased perfusion. Dobutamine infusion allows for evaluation of myocardial contractile reserve by increasing inotropism. In low doses it gives us information on regional viability. In high doses, wall motion under increased oxygen demand, it becomes dependent on the ability of the coronary arteries to increase blood flow. Dipyridamole induces coronary vasodilation. In low doses it produces an increase in the blood flow. In high doses the steal effect deviates blood from the regions dependent on stenosed arteries. Ischaemia and regional wall motion abnormalities ensue. A negative stress echocardiogram, either under dobutamine or dipyridamole, has an excellent negative predictive value while a positive stress echocardiogram is predictive of an increased rate of events in the follow-up.