This release concerns a Ph.D. thesis at the Erasmus University in Rotterdam
Rotterdam, 16 June 2005 - Despite the trend towards more individual diagnostic evaluation and clinical care, the predictive value of stress echocardiography was often evaluated in unselected, mixed patient groups. Elena Biagini evaluates multiple echocardiographic approaches and techniques in specific patient groups to predict clinical and functional outcome. Biagini will take her doctoral degree on 22 June 2005.
- Role of dobutamine stress echocardiography for prediction of cardiac events in patients with known or suspected coronary artery disease. -
The first part of her thesis deals with the assessment of prognostic value of dobutamine stress echocardiography in specific patient subsets. Dobutamine stress echocardiography has a high accuracy for the detection of coronary artery disease. Additionally it provides clinically useful prognostic information, such as resting left ventricular function, myocardial viability, stress-induced ischemia, vascular extent of wall motion abnormalities, and changes of end systolic volume and ejection fraction with stress. The timing, extent and severity of the stress-induced wall motion abnormalities are important determinants of long-term prognosis. Previous studies have shown the efficacy of stress echocardiography in predicting long-term cardiac events in mixed patient groups and the value of this test in selected patient subsets. As medicine develops there is a trend towards more individual diagnostic evaluation and clinical care. Prediction of future cardiac events may be a clinical challenge in some patients because of anatomical differences, inability to exercise, and pre-existent repolarization abnormalities. In this thesis specific patient groups were evaluated. The prognostic value of dobutamine stress echocardiography was studied in multiple patient subsets, as women, elderly, patients with silent ischemia, and those with intraventricular conduction abnormalities.
- Myocardial viability detected by low dose dobutamine infusion and tissue Doppler imaging. -
The role of myocardial viability in patients with dilated ischemic cardiomyopathy was evaluated by low dose dobutamine stress echocardiography in patients who underwent to different treatments. In patients who underwent myocardial revascularization, the relation between viable myocardium and ongoing or reversed remodeling was evaluated. Substantial myocardial viability prevented ongoing left ventricular remodeling after revascularization and was associated with improvement of symptoms and favorable long-term prognosis. In patients who underwent percutaneous transplantation of skeletal myoblasts, resting left ventricular function and myocardial viability were evaluated by resting and low dose dobutamine echocardiography and by tissue Doppler imaging examination. During low-dose dobutamine infusion, the peak systolic velocity in the regions of myoblasts injection significantly increased at tissue Doppler imaging examination; left ventricular ejection fraction improved and end-systolic volumes decreased at 1 year. Thus, in these patients, regional and global left ventricular contractile reserve showed a sustained improvement, up to 1 year after treatment.
- Myocardial contrast echocardiography. -
In patients with acute myocardial infarction, myocardial contrast echocardiography may be useful to assess dysfunctional myocardium after primary percutaneous revascularization and distinguish reversible (myocardial stunning) from irreversible myocardial damage (no-reflow phenomenon). Moreover, several studies demonstrate that myocardial contrast echocardiography can predict the recovery of regional function after primary percutaneous coronary intervention. The additional value of end-diastolic myocardial wall thickness was evaluated together with myocardial contrast echocardiography to predict recovery of regional left ventricular function after primary coronary intervention. A relatively simple measurement of end-diastolic myocardial wall thickness, obtained with 2-D echocardiography combined with contrast agent, predicted recovery of regional contractile function. Using end-diastolic myocardial wall thickness alone, dysfunctional segments with an end-diastolic myocardial wall thickness >=11 mm showed a high likelihood of recovery of regional contractile function two months after primary coronary intervention. Moreover, it appeared that when at least 50% of the dysfunctional segments showed an EDWT >=11 mm, global recovery may be anticipated. The relative merits of myocardial contrast echocardiography and magnetic resonance imaging to predict myocardial function improvement after percutaneous coronary intervention was evaluated. The sensitivity, specificity and accuracy for the prediction of functional improvement were comparable between myocardial contrast echocardiography, first-pass magnetic resonance imaging, and delayed-enhancement magnetic resonance imaging. Thus, myocardial contrast echocardiography, as bed-side technique, may be an alternative tool in the acute phase of myocardial infarction.
- Predictive echocardiography in hypertrophic cardiomyopathy. -
The incidence, risk factors and prognosis of dilated-hypokinetic evolution in 222 consecutive patients with hypertrophic cardiomyopathy was evaluated over 11 years. Patients with prevalent/incident dilated-hypokinetic hypertrophic cardiomyopathy were younger at first evaluation, more often had a family history of hypertrophic cardiomyopathy or sudden death, and showed greater myocardial wall thickness compared with patients who maintained 'classic' hypertrophic cardiomyopathy. Cox proportional hazards regression analysis identified left ventricular wall thickness and end-diastolic diameter both measured by 2-D echocardiography as independent predictors of cardiovascular death. In patients with obstructive hypertrophic cardiomyopathy who underwent percutaneous septal myocardial ablation, the role of intracardiac echocardiography was evaluated. This imaging modality was useful in the selection of the appropriate septal branch and in guiding ethanol administration. The planimetric ablated area (with ethanol) visualized by intracardiac echocardiography correlated with the infarct size measured by delay-enhancement magnetic resonance imaging at 4 days after the procedure.
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