title: Effects of surgical ventricular restoration on left ventricular contractility assessed by a novel contractility index in patients with ischemic cardiomyopathy.
abstract: A pressure-normalized left ventricular (LV) wall stress (dsigma*/dt(max)) was recently reported as a load-independent index of LV contractility. We hypothesized that this novel contractility index might demonstrate improvement in LV contractile function after surgical ventricular restoration (SVR) using magnetic resonance imaging. A retrospective analysis of magnetic resonance imaging data of 40 patients with ischemic cardiomyopathy who had undergone coronary artery bypass grafting with SVR was performed. LV volumes, ejection fraction, global systolic and diastolic sphericity, and dsigma*/dt(max) were calculated. After SVR, a decrease was found in end-diastolic and end-systolic volume indexes, whereas LV ejection fraction increased from 26% +/- 7% to 31% +/- 10% (p <0.001). LV mass index and peak normalized wall stress were decreased, whereas the sphericity index (SI) at end-diastole increased, indicating that the left ventricle became more spherical after SVR. LV contractility index dsigma*/dt(max) improvement (from 2.69 +/- 0.74 to 3.23 +/- 0.73 s(-1), p <0.001) was associated with shape change as evaluated by the difference in SI between diastole and systole (r = 0.32, p <0.001, preoperative; r = 0.23, p <0.001, postoperative), but not with baseline LV SI. In conclusion, SVR excludes akinetic LV segments and decreases LV wall stress. Despite an increase in sphericity, LV contractility, as determined by dsigma*/dt(max), actually improves. A complex interaction of LV maximal flow rate and LV mass may explain the improvement in LV contractility after SVR. Because dsigma*/dt(max) can be estimated from simple noninvasive measurements, this underscores its clinical utility for assessment of contractile function with therapeutic intervention.
authors.affiliation: Department of Cardiology, National Heart Centre, Singapore; College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhong
authors.forename: Srikanth
authors.initials: S
authors.lastname: Sola
authors.forename: Ru-San
authors.initials: RS
authors.lastname: Tan
authors.forename: Thu-Thao
authors.initials: TT
authors.lastname: Le
authors.forename: Dhanjoo N
authors.initials: DN
authors.lastname: Ghista
authors.forename: Vikram
authors.initials: V
authors.lastname: Kurra
authors.forename: Jose L
authors.initials: JL
authors.lastname: Navia
authors.forename: Ghassan S
authors.initials: GS
authors.lastname: Kassab
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D009202:Cardiomyopathies / Q000209:etiology* / Q000601:surgery*; D001026:Coronary Artery Bypass; D005260:Female; D006352:Heart Ventricles / Q000601:surgery*; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D015588:Observer Variation; D015203:Reproducibility of Results; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology* / Q000601:surgery*; D016277:Ventricular Function, Left