Page 101 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax
P. 101

Coronary autoregulation and fatal events in stable CAD
Before percutaneous coronary intervention, intracoronary pressure was
measured with a 0.014" pressure sensor–equipped guidewire (Volcano Corp,
San Diego, CA). Coronary blood flow velocity was subsequently measured with
a 0.014" Doppler crystal–equipped guidewire (Volcano Corp, San Diego, CA). Hyperemia was induced by an intracoronary bolus of adenosine (20–40 μg).
Fractional flow reserve was defined as the ratio of mean distal coronary pressure
to mean aortic pressure in the target vessels during maximal hyperemia. CFVR
was defined as the ratio of hyperemic to baseline average peak blood flow
velocity (APV) distal to the target lesions. CFVR was additionally assessed in
an angiographically normal reference coronary artery, defined as a coronary
artery with <30% irregularities on visual assessment, if present. A reference
vessel CFVR >2.7 was considered normal.10 From the recorded intracoronary hemodynamic data, both the hyperemic stenosis resistance index,9 defined
as the ratio between the pressure gradient across the stenosis and distal APV
during maximal hyperemia, and the microvascular resistance index,11 defined
as mean distal coronary pressure divided by distal APV, were calculated. In 6 the absence of significant epicardial disease, microvascular resistance index
in the reference vessel was calculated as the mean aortic pressure divided by distal APV. In the presence of 2-vessel CAD, the most severe coronary lesion by hyperemic stenosis resistance index was depicted as the target lesion and was used for subsequent target vessel analyses.
Patients underwent percutaneous coronary intervention of all ischemia- causing lesions at the discretion of the operator. Decisions on further treatment and medication during follow-up were entirely left to the discretion of the treating cardiologist.
Long-term Follow-up
Long-term follow-up was performed by identifying patients in the Dutch national population registry to assess the occurrence of death. In addition, the cause of death was verified by evaluating hospital records or by contacting the general practitioner. Death was considered cardiac unless an unequivocal noncardiac cause was documented.12
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