Pressure-Flow Measurements Directly after Primary PCI to Predict Late Occurrence of Microvascular Obstruction

Over the past decades, the use of advanced revascularization strategies such as
primary percutaneous coronary intervention (PCI) in patients with acute
myocardial infarction (AMI) has led to a strong decrease in mortality.
Following primary PCI, patency of the occluded coronary artery is achieved in
more than 90% of the patients. However, despite successful primary PCI, a large
proportion of patients with AMI show inadequate myocardial perfusion, due to
microvascular obstruction (MVO). This is also known as the *no reflow*
phenomenon and leads to severe impairment of the left ventricle. It is
estimated that it occurs in about 40% of patients undergoing primary PCI.
Patients with MVO have a largely increased risk for development of heart
failure which has a major impact on quality of life and leads to frequent
hospital admissions, high use of medication and thus hight costs in hospital
care. Futhermore it also leads to an increased mortality. So, the importance of
the treatment of MVO seems very important and thus is designated as *the next
hurdle in interventional cardiology*.
The process of development of MVO is multifactorial. Myocardial ischemia causes
a relative decrease in the bioavailability of nitric oxide, a potent
vasodilator, while an excess of vasoconstrictors, such as endothelin-1 and
tissue factor are present. Oxygen free radicals further damage endothelial
cells and myocytes. Endothelial cell injury promotes the activation of
platelets, the upregulation of adhesion molecules and the release of
inflammatory mediators that subsequently initiate inflammatory and coagulation
cascades.
Pharmacological intervention potentially could limit the damage caused by MVO.
Unfortunately, no such treatment is available yet. Several compounds did show
beneficial effects in experimental models and it is conceivable that for
example fibrinolytic or anti-inflammatory compounds will be effective. Drugs
aiming to prevent MVO are ideally applied directly after performance of the
PCI. This will ensure largest possible efficacy of the drug because prior to
PCI the artery is occluded. A potential additional advantage to start treatment
immediately after PCI is the fact that drugs can be administered directly into
the coronary artery, with a catheter still in place.

In the present study we aim to determine the value of microvascular resistance
measurements in the acute setting to predict the occurrence of MVO in the
following days, using the combined pressure-flow wire. Therefore patients with
an acute MI will undergo a single resistance measurement directly following
successful revascularization and stent-placement. These measurements will then
be correlated to MRI measurements of MVO, performed at day 4 after the acute
event.

single center prospective cohort study

Minimal risk. Two extra invasive procedures take place, these are the
intracoronary resistance measurement using the combowire and the intracoronary
thermodilution measurement using the PressureWire Certus. During standard PCI,
many different wires are inserten into the coronary arteries and the risks of
such procedures is limited (<1%). Intravenous infusion of adenosine, compared
to placebo, gives minimal negative side-effects. Hypotension, which in most
cases is tolerated well, is the most frequent occuring side-effect. Serious
side-effects of intravenous adenosine are not reported.