The role of MRI viability testing to decide on percutaneous coronary interventions strategies of complex coronary artery disease.

Revascularisation has proven to be of benefit for survival of patients with
left main or 3-vessel disease and depressed systolic left ventricular function
when compared to medical therapy. The evidence is largely based on two
non-randomised surgical studies performed almost 20 years ago. Randomized
studies evaluating the effect of percutaneous coronary interventions (PCI) on
survival in such patients are not performed. Improvement of left ventricular
function can be used as a surrogate and ejection fraction is presently used as
selection criteria for ICD implantation. Studies on the effect of PCI on left
ventricular function are limited and not focussed on patients with 3-vessel
disease and depressed systolic LV function.
The effect of revascularisation in patients with depressed systolic left
ventricular function can be predicted by establishing the viability of hypo- or
akinetic segments. MRI has been recently introduced as non-invasive imaging
tool that can identify reversible dysfunctional myocardium since it offers
transmural differentiation of necrotic and viable myocardium in the setting of
chronic myocardial infarction. The transmural extent of infarction predicts
regional functional recovery after revascularization and the extent of
dysfunctional but viable myocardium predicts recovery of global left
ventricular function. However, in myocardial segments with >25% to <75%
transmural extent of infarction, prediction of improvement is less reliable. In
a first study on recovery of wall motion after percutaneous recanalisation of
chronic total occluded coronary arteries we observed the same limitation.
Alternatively low-dose dobutamine MRI can be used to establish viability and
may especially be useful for segments with an intermediate extent of viability.
Quantitative assessment of wall motion by tagging combined with rapid post
processing algorithms may be another less cumbersome and more quantitative
option to improve sensitivity and specificity.

Delayed enhanced MRI and low-dose dobutamine MRI are relative new techniques
which offer an increased resolution to investigate prior myocardial infarction
and functional myocardial reserve. This project will increase the knowledge in
MRI as diagnostic tool and lead to prediction rules before complex coronary
interventions. In the near future the techniques developed may guide treatment
of the individual patient. This may lead to reduction in cost by avoiding
unnecessary interventions or reduction of vessels treated.

To evaluate the predictive value of different MRI techniques to establish
viability to guide percutaneous interventions decisions in patients with
complex coronary artery disease.

The project will be a prospective follow-up study where one hundred patients
will be studied before, 6 and 12 months after percutaneous intervention with
contrast enhanced cardiac MRI. Two patient groups will be included.
First group will be patients (N =50) referred for PCI of complex coronary
artery disease defined as a chronic total occlusion (CTO) with regional wall
motion abnormalities.
The second group will be patients (N =50) referred for PCI in multivessel
disease with severe depressed LV function (EF< 35%).

The patient has to visit the hospital one time before the PCI and 6 and 12
months after the PCI-procedure.
The patient will be informed concerning the procedure; the breath hold,
contrast injection and dobutamine injection will be explained. An intravenous
catheter will be placed in the antecubital vein. ECG monitoring leads and a
brachial blood pressure curve will be applied.
During the scan the patient will be continuously monitored with ECG leads.
Systolic and diastolic blood pressures will be recorded with an automatic
device at baseline and every 3 minutes. After baseline acquisitions dobutamine
(5-10 mcg/kg/min) will be infused intravenously using a pump injector. During
the infusion of dobutamine the researcher and the cardiologist will be present
to monitor the conditions of the patient and to evaluate the images. Patient
and researcher will be able to communicate at every moment, ensuring good
clinical conditions of the patient. MRI is not dangerous for the patient
physically.

Dobutamine;
Dobutamine can rise the blood pressure with 10-20 mmHg. When the patient is
known with hypertension, blood pressure can rise with 40 mmHg.
In 1-3%; headache, nausea, angina.
Pregnant patients will be excluded in this study because there is less known
about the effects of dobutamine in pregnant women.