Risk Stratification after Myocardial Infarction using Dobutamine Stress Echocardiography

Anand, Gnanaraj (2006) Risk Stratification after Myocardial Infarction using Dobutamine Stress Echocardiography. Masters thesis, Stanley Medical College, Chennai.

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Abstract

Introduction : Pharmacological stress testing has emerged as an important diagnostic tool in the evaluation and management of patients with known coronary artery disease, especially those who cannot perform physical exercise. It has also become an important modality to assess myocardial viability, hibernating myocardium and valvular heart disease. Unlike exercise stress testing in which cardiac imaging is not always needed, pharmacological stress test needs some form of imaging to detect myocardial ischaemia. Pharmacological stress tests with vasodilatation, using dipyridamole or adenosine, have been used extensively in conjunction with nuclear perfusion imaging1. Recently pharmacological stress echocardiography has become an accepted alternative to exercise stress testing and to stress testing with nuclear imaging. Many pharmacological agents have been used for stress testing. Dipyridamole and adenosine are used commonly in some places in combination with echocardiographic imaging. Dobutamine is the preferred agent in some parts of the world, like the United States. More and more cardiac laboratories consider dobutamine as the drug of choice for stress testing. A newer drug Arbutamine is also approved for this purpose. Aims of the Study : To assess the myocardial viability after myocardial infarction using dobutamine stress Echocardiography. To study the various high risk variables that affect the viability of the myocardium after myocardial infarction. To detect the significance of regional wall motion abnormality during the dobutamine stress echocardiography in the prediction of coronary events after myocardial infarction To evaluate the factors that predict the coronary events and the presence of myocardial viability after myocardial infarction. To stratify the risk of the patients for coronary events following myocardial infarction using the dobutamine stress echocardiographic responses at low doses and high doses. To assess the negative predictive value of dobutamine stress echocardiography in the post myocardial infarction setting. Conclusion : In our post myocardial infarction dobutamine stress echocardiography study, which also assessed the risk stratification and follow up for 6 months, the following conclusions were made 1. It is safe to do Dobutamine Stress Echocardiography in post myocardial infarction patients, even in the early post infarction period, with very low complication rate and risk to life. 2. Thrombolysis had a significant effect on viability, especially in the group, which showed a biphasic response. 3. Smoking affected the presence of myocardial viability significantly. 4. Patients with diabetes showed more biphasic response, signifying an increased prevalence of obstructive coronary artery disease. 5. Patients with normal dobutamine stress echocardiography had no events on follow up, establishing its negative predictive value. 6. Patients who had a biphasic response had the maximum number of events compared to all the other groups. This group should be considered for early coronary revascularization. 7. The presence of a prior myocardial infarction predicted absence of viability and the absence of prior myocardial infarction predicted presence of viability. 8. Ejection fraction is a major predictor of events especially heart failure. It also predicted the coronary events significantly.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Risk Stratification ; Myocardial Infarction ; Dobutamine ; Stress ; Echocardiography.
Subjects: MEDICAL > Cardiology
Depositing User: Kambaraman B
Date Deposited: 06 Jul 2017 01:27
Last Modified: 06 Jul 2017 09:59
URI: http://repository-tnmgrmu.ac.in/id/eprint/1057

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