Myocardial perfusion in patients with permanent ventricular pacing and normal coronary arteries.
OBJECTIVE
The purposes of this study were to test the specificity of dipyridamole myocardial perfusion scintigraphy in patients with permanent ventricular pacing (PVP) and to evaluate coronary blood flow and reserve in these patients.


BACKGROUND
Permanent ventricular pacing is associated with exercise perfusion defects on myocardial scintigraphy in the absence of coronary artery disease (CAD). On the basis of studies in patients with left bundle brunch block, coronary vasodilation with dipyridamole has been proposed as an alternative to exercise testing for detecting CAD in paced patients, but this approach has never been tested.


METHODS
Fourteen patients with a PVP and normal coronary arteries underwent stress thallium-201 scintigraphy and cardiac catheterization. In these patients and in eight control subjects, coronary flow velocities were measured in the left anterior descending coronary artery (LAD) and in the dominant coronary artery before and after adenosine administration.


RESULTS
In the paced patients, coronary flow velocities in the LAD and in the dominant coronary artery were significantly lower than those in the control subjects. In addition, seven patients showed perfusion defects on dipyridamole thallium-201 single-photon emission computed tomography, with a specificity of 50% for this test. The defect-related artery in these patients had lower coronary flow reserve (2.6 +/- 0.5) as compared with those without perfusion defects (3.9 +/- 1.0, p < 0.05) or the control group (3.5 +/- 0.5, p < 0.05).


CONCLUSIONS
Permanent ventricular pacing is associated with alterations in regional myocardial perfusion. Furthermore, abnormalities of microvascular flow, as indicated by reduced coronary flow reserve in the defect-related artery, are at least partially responsible for the uncertain specificity of dipyridamole myocardial perfusion scintigraphy.
Skalidis
E I
EI
Department of Cardiology, University Hospital of Heraklion, Crete, Greece.
Kochiadakis
G E
GE
Koukouraki
S I
SI
Chrysostomakis
S I
SI
Igoumenidis
N E
NE
Karkavitsas
N S
NS
Vardas
P E
PE
D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy; D003326:Coronary Circulation / Q000502:physiology*; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D003937:Diagnosis, Differential; D004176:Dipyridamole; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000503:physiopathology; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D010138:Pacemaker, Artificial; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon
D013794:Thallium Radioisotopes; D004176:Dipyridamole