Hyperaemic microvascular resistance is not increased in viable myocardium after chronic myocardial infarction.
OBJECTIVE
The present study compared microvascular resistance (MR) of viable myocardium in infarct areas with those in reference areas in patients with chronic myocardial infarction (MI).


RESULTS
In 27 patients, MR (ratio distal coronary pressure and flow) of reference and viable infarct areas was calculated at baseline and during hyperaemia. H2 15O positron emission tomography (PET) was used to provide myocardial blood flow measurements. In infarct regions, H2 15O PET solely measures flow in viable myocardium, excluding flow in scar tissue. Distal coronary pressure was measured with a pressure wire in the infarct-related and reference artery. The average time between PET study and infarction was 3.3+/-4.4 years. Mean hyperaemic distal coronary pressure was significantly lower in the infarct-related artery. MR varied considerably between patients and was significantly higher in infarct areas at baseline (135+/-38 vs. 118+/-29 mmHg mL min/mL; P<0.05), but not during hyperaemia (39+/-18 vs. 35+/-11 mmHg mL min/mL). The correlation between MR in infarct and reference areas was significant.


CONCLUSIONS
To determine MR, distal coronary pressure measurements should be used. Hyperaemic MR in viable myocardium within the infarcted area is not higher when compared with the reference area. This supports the application of the established fractional flow reserve cut-off value in the setting of chronic MI.
Marques
Koen M
KM
Department of Cardiology, VU University Medical Centre, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam, The Netherlands. km.marques@vumc.nl
Knaapen
Paul
P
Boellaard
Ronald
R
Westerhof
Nico
N
Lammertsma
Adriaan A
AA
Visser
Cees A
CA
Visser
Frans C
FC
D000368:Aged; D001783:Blood Flow Velocity; D002908:Chronic Disease; D003326:Coronary Circulation / Q000502:physiology*; D023921:Coronary Stenosis / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008833:Microcirculation / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology*; D049268:Positron-Emission Tomography; D011312:Pressure; D014655:Vascular Resistance