Myocardial Viability in Ischemic Left Ventricular Dysfunction Clinical Trial
Official title:
The Use of Myocardial Deformation Imaging Based on Ultrasonic Pixel Tracking to Identify Reversible Myocardial Dysfunction
Myocardial deformation imaging allows analysis of myocardial viability in ischemic left
ventricular dysfunction. This study will evaluate the predictive value of myocardial
deformation imaging for improvement in cardiac function after revascularization therapy in
comparison to contrast-enhanced cardiac magnetic resonance imaging (ceMRI).
In 55 patients with ischemic left ventricular dysfunction, myocardial viability was assessed
using pixel-tracking-derived myocardial deformation imaging and ceMRI to predict recovery of
function at 9±2 months follow-up. For each left ventricular segment in a 16-segment model
peak systolic radial strain will be determined from parasternal 2D echocardiographic views
and the amount of late hyperenhancement (LE) and maximal thickness of myocardial tissue
without LE using ceMRI. The hypothesis is that compared with segments showing functional
improvement, those that failed to recover had lower radial strain and lower thickness
without LE and higher LE.
Between August 2004 and June 2006 195 patients with ischemic left ventricular dysfunction
underwent MRI for the definition of myocardial viability. Onehundred-ten patients with
non-ischemic cardiomyopathy or acute coronary syndromes were excluded from the study to
avoid possible acute ischemia or stunning. Within the 85 patients with chronic ischemic
heart disease, six patients refused participation in this study and five patients had
echocardiographic windows insufficient for participation. Within the remaining 74 patients
55 patients underwent revascularization and 19 had no revascularization. These 55 patients
form our study group! Functional recovery will be assessed using echocardiographic images
before and 9±2 months after revascularization with a Vivid Seven System (GE Vingmed, Horton,
Norway). Parasternal long-axis and short-axis views at basal, midventricular and apical
levels, as well as 3 standard apical views (4 chamber, 2 chamber, and long axis) have been
acquired (frame rate 56 to 92 frames/s). Segmental wall motion will be determined using the
following score: 1=normokinetic, 1.5= mildly hypokinetic, 2= moderately or severely
hypokinetic, 3= akinetic, or 4= dyskinetic. A segment is considered to demonstrate
functional improvement during follow-up if it improved by at least 1 grade. Global
functional recovery was considered in case of an increase in ejection fraction>5% at
follow-up.
The three acquired parasternal short axis views will be analysed with the aid of a dedicated
software package (EchoPAC BT 05.2, GE Vingmed, Horton, Norway). This system allows analysis
of peak systolic circumferential and radial strain from short axis views based on detection
of natural acoustic markers. The system calculates mean strain values for whole predefined
LV segments, including all myocardial layers from the endocardium to epicardium.
All patients underwent cMRI within a few hours of the baseline echocardiographic study on a
1.5-T whole-body MR scanner (Intera, Best, Philips, the Netherlands). The assignment to a
hyperenhancement category reflects the extent of hyperenhancement within each segment by
visual assessment considering a 5-group scale: 0% hyperenhancement (group 1), 1 to 25%
hyperenhancement (group 2), 26 to 50% hyperenhancement (group 3), 51 to 75% hyperenhancement
(group 4) and 76 to 100% hyperenhancement (group 5).
In addition, the maximal thickness of myocardial tissue without late hyperenhancement will
be determined for each LV segment. This is considered to be a parameter of the remaining
viable myocardium.
;
Observational Model: Defined Population, Primary Purpose: Screening, Time Perspective: Longitudinal