Resting myocardial blood flow, coronary flow reserve, and contractile reserve in hibernating myocardium: implications for using resting myocardial contrast echocardiography vs. dobutamine echocardiography for the detection of hibernating myocardium.
OBJECTIVE
Controversy exists regarding the relative status of resting myocardial blood flow (MBF), coronary flow reserve (CFR), and contractile reserve (CR) in hibernating myocardium (HM). We hypothesized that CFR is more profoundly affected than resting MBF parameters in HM. Thus, resting MBF assessed by myocardial contrast echocardiography (MCE) will be more sensitive than CR elicited by dobutamine stress echocardiography (DSE) for the detection of HM.


RESULTS
Accordingly 27 patients with ischaemic cardiomyopathy underwent resting MCE and DSE prior to revascularisation, of which 23 patients underwent follow-up echocardiography at 179 ± 66 days after revascularization. Qualitative and quantitative MCE [contrast intensity (A, dB)], MBF (represented by blood velocity β, dB/s), and CFR (vasodilator β/rest β, β reserve) were obtained. CR was obtained during DSE. Resting contrast intensity (7.2 ± 2.3 dB) and β (0.67 ± 0.47 dB/s) were significantly (P < 0.005 and <0.01, respectively) reduced in HM vs. remote normal myocardium but significantly higher compared with non-viable segments (4.4 ± 2.3 dB and 0.43 ± 0.32 dB/s, respectively). However, CFR was significantly (0.82 ± 3.2 (P = 0.01)) lower in HM compared with normal (1.8 ± 1.02) but not significantly reduced when compared with non-viable myocardium (1.1 ± 3.3). Sensitivity for the detection of HM with qualitative and quantitative MCE were 82 and 87%, respectively, compared with 67% (P < 0.0001) by DSE with similar specificity of 55 and 67%, respectively, compared with 63% with DSE.


CONCLUSIONS
Resting MBF but not CFR distinguished HM from non-viable myocardium. Resting MCE and not DSE was more accurate for the prediction of HM.
Hickman
Michael
M
Department of Cardiology, Northwick Park Hospital, Harrow HA1 3UJ, UK.
Chelliah
Rajesh
R
Burden
Leah
L
Senior
Roxy
R
D000368:Aged; D000704:Analysis of Variance; D003287:Contrast Media; D003326:Coronary Circulation / Q000502:physiology; D004452:Echocardiography / Q000379:methods*; D025401:Echocardiography, Stress; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D017682:Myocardial Stunning / Q000000981:diagnostic imaging* / Q000209:etiology; D010743:Phospholipids; D020127:Recovery of Function; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013459:Sulfur Hexafluoride
D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride