Evidence of reduced resting blood flow in viable myocardial regions with chronic asynergy.
OBJECTIVE
We tested the hypothesis in patients (n = 24) with ischemic heart disease that chronic contractile dysfunction occurs in myocardial regions with true reduction in rest blood flow.


BACKGROUND
Whether viable myocardial regions with chronic contractile dysfunction have true reduction in rest myocardial blood flow is controversial.


METHODS
Positron emission tomography (PET) 13N-ammonia was used to measure myocardial blood flow in combination with 18F-fluorodeoxyglucose (18FDG) to assess myocardial viability. Viability also was assessed by dobutamine echo and recovery of function after coronary artery bypass grafting (CABG). Segments (n = 252) were selected based on PET measured reduced resting blood flow and rest asynergy on echo.


RESULTS
Regional myocardial viability was present in 20 of 23 patients by PET, 13 of 23 by dobutamine echo and 10 of 11 by postrevascularization criteria. Rest blood flow in normal regions was 1.14+/-0.52 ml/min/g and by definition exceeded (p < 0.005) that in both viable (0.48+/-0.15; n = 8 patients) and nonviable (0.45+/-0.14; n = 8 patients) regions (post-CABG criteria), which did not differ. Correction of rest myocardial blood flow in viable asynergic segments, only, for fibrosis and incomplete tracer recovery raised the level to 0.67+/-0.21 (p < 0.005 vs. normal). Finally, evidence of both stunning (rest asynergy with normal flow) and hibernation was present in 15 of 23 (65%) patients.


CONCLUSIONS
Reduced rest blood flow in viable myocardial regions with chronic asynergy is common and cannot be accounted for by partial volume effect. Thus, hypotheses concerning physiologic mechanisms underlying chronic contractile dysfunction should consider the role played by chronic reduction of basal myocardial blood flow.
Tawakol
A
A
Department of Medicine, Cardiac Unit, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
Skopicki
H A
HA
Abraham
S A
SA
Alpert
N M
NM
Fischman
A J
AJ
Picard
M H
MH
Gewirtz
H
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002316:Cardiotonic Agents; D003326:Coronary Circulation; D004280:Dobutamine; D005260:Female; D019788:Fluorodeoxyglucose F18; D006439:Hemodynamics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D019275:Radiopharmaceuticals; D014055:Tomography, Emission-Computed; D014463:Ultrasonography
D002316:Cardiotonic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D004280:Dobutamine