This large international radiation dose survey demonstrates considerable reduction of radiation exposure in coronary CTA during the last decade. However, the large inter-site variability in radiation exposure underlines the need for further site-specific training and adaptation of contemporary cardiac scan protocols.
Objectives: To test whether an increase in Doppler myocardial performance index (MPI) during dobutamine stress echocardiography, reflecting deterioration of overall left ventricular function, is associated with increased N-terminal pro-brain natriuretic peptide (NT-pro-BNP) concentration and provides prognostic information beyond conventional systolic wall motion analysis after acute myocardial infarction (AMI). Design: Prospective, observational study. Methods: Dobutamine-atropine stress echocardiography (DASE) and NT-pro-BNP were assessed five days after AMI in 109 consecutive patients. MPI was measured at rest and at low-dose (10 mg/kg/min) and peak dobutamine infusion (( 40 mg/kg/min with or without atropine). Main outcome measures: End point was a composite of cardiac death or readmission for heart failure or reinfarction. Results: In 35 patients (32%), MPI increased at low-dose DASE. This was associated with higher NT-pro-BNP concentrations (b = 0.30, p = 0.004). During a mean follow up of 27 (SD 7) months, 8 patients died of cardiac causes and 15 patients were readmitted for heart failure or reinfarction. On Cox regression analysis, an increase in MPI at low-dose DASE (p = 0.02) was an independent predictor of cardiac events. In contrast, traditional wall motion analysis during DASE provided no additional prognostic information. Conclusions: An increase in MPI at low-dose DASE, reflecting early deterioration of overall left ventricular function, is associated with raised NT-pro-BNP concentration and provides prognostic information beyond conventional stress echocardiographic data after AMI. I nducible myocardial ischaemia may be detected and quantified by dobutamine-atropine stress echocardiography (DASE) after acute myocardial infarction (AMI). The detection of ischaemia is based on semiquantitative wall motion analysis, however, which assesses only left ventricular (LV) systolic function. The Doppler echocardiographic myocardial performance index (MPI) is a quantitative measure of combined LV systolic and diastolic function. [1][2][3] Because impaired LV diastolic function precedes LV systolic dysfunction during myocardial ischaemia, 4 quantitative assessment of changes in both systolic and diastolic LV function seems appealing and may potentially increase the clinical yield of DASE after AMI. Data on the changes in MPI during stress echocardiography are limited. Recently, MPI was found to correlate closely with invasive measures of LV systolic function during b adrenergic stimulation. 5 Furthermore, we have previously shown that MPI consistently improves, decreasing its value, during dobutamine stimulation in healthy people, 6 and MPI has been shown to increase (deteriorate) during dobutamine-induced ischaemia in patients with known or suspected coronary artery disease.
Following myocardial infarction low QT dispersion is associated with preserved left ventricular function, whereas persistently increased dispersion is associated with left ventricular dilation and deterioration of diastolic function.
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