No differences in rest myocardial blood flow in stunned and hibernating myocardium: insights into the pathophysiology of ischemic cardiomyopathy

• Published in: European journal of nuclear medicine and molecular imaging Vol. 46; no. 11; pp. 2322 - 2328
• Main Authors: Benz, Dominik C., von Dahlen, Anita P., Huang, Wenjie, Messerli, Michael, von Felten, Elia, Benetos, Georgios, Giannopoulos, Andreas A., Fuchs, Tobias A., Gräni, Christoph, Gebhard, Catherine, Pazhenkottil, Aju P., Gaemperli, Oliver, Kaufmann, Philipp A., Buechel, Ronny R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2019; Springer Nature B.V
• Subjects: Aged; Ammonia; Blood flow; Cardiology; Cardiomyopathies; Cardiomyopathy; Echocardiography; Emission analysis; Female; Fluorodeoxyglucose F18; Heart; Heart - diagnostic imaging; Heart - physiopathology; Hibernation; Humans; Imaging; Ischemia; Male; Medicine; Medicine & Public Health; Middle Aged; Motion; Myocardial Ischemia - diagnostic imaging; Myocardial Ischemia - physiopathology; Myocardial Perfusion Imaging; Myocardium; Myocardium - pathology; Myocytes; Nuclear Medicine; Oncology; Original Article; Orthopedics; Perfusion; Positron emission; Positron emission tomography; Predictive Value of Tests; Radiology; Rest; Retrospective Studies; Ventricular Dysfunction, Left; Viability; Myocardial blood flow; Stunning; Hibernating myocardium; Myocardial flow reserve; Viability testing
• ISSN: 1619-7070; 1619-7089; 1619-7089
• DOI: 10.1007/s00259-019-04440-2

Purpose The human pathophysiology of stunned, hibernating and scarred myocardium in ischemic cardiomyopathy is a subject of controversy. While the “smart heart” theory postulates that reduced myocardial blood flow (MBF) at rest is responsible for myocytes switching to a state of hibernation, other theories suggest that a reduced myocardial flow reserve (MFR) may be the cause. Methods We included 110 patients with ischemic cardiomyopathy. Based on quantitative myocardial perfusion assessment and viability imaging with 13 N-NH3 and 18 F-FDG positron emission tomography, respectively, as well as wall motion assessment from echocardiography, myocardial tissue was characterized as remote (i.e., normal myocardium), stunned (i.e., dysfunctional but viable myocardium with normal rest perfusion), hibernating (i.e., dysfunctional but viable myocardium with impaired rest perfusion), or scarred myocardium (i.e., non-viable myocardium). Results Compared to remote myocardium, dysfunctional but viable myocardium (including stunned and hibernating) had reduced rest MBF (0.89 mL/min/g vs. 0.79 and 0.76 mL/min/g, respectively; p  < 0.001) and MFR (1.53 vs. 1.27 and 1.17; p  < 0.001). Between stunned and hibernating myocardium, however, rest MBF and MFR did not differ ( p  = 0.40). In scarred myocardium, rest MBF was lowest (0.66 mL/min/g; p  < 0.001) but, in contrast to the other myocardial states, k2 (i.e., tracer washout) was increased (0.199/min vs. 0.178/min to 0.181/min; all p  < 0.05 in pairwise comparison). Conclusions In patients with ischemic cardiomyopathy, impaired MFR is associated with stunning and hibernation. These states of dysfunctional but viable myocardium have lower rest MBF compared to remote myocardium. At the end of the continuum, rest MBF is lowest in scar tissue and linked to increased rate of tracer washout.