Association of noninvasively measured left ventricular mechanics with in vitro muscle contractile performance: a prospective study in hypertrophic cardiomyopathy patients.
BACKGROUND
Hypertrophic cardiomyopathy (HCM) is a primary myopathic process in which regional left ventricular dysfunction may exist without overt global left ventricular dysfunction. In obstructive HCM patients who underwent surgical myectomy (SM), we sought to determine if there is a significant association between echocardiographic longitudinal strain, histopathology, and in vitro myocardial performance (resting tension and developed tension) of the surgical specimen.


RESULTS
HCM patients (n=122, 54±14 years, 54% men) undergoing SM were prospectively recruited. Longitudinal systolic strain and diastolic strain rates were measured at that basal septum (partially removed at SM) by using velocity vector imaging on preoperative echocardiography. Semiquantitative histopathologic grading of myocyte disarray and fibrosis and in vitro measurements of resting tension and developed tension were made in septal tissue obtained at SM. Mean basal septal systolic strain and diastolic strain rate were -8.3±5% and 0.62±0.4/s, while mild or greater degree of myocyte disarray and interstitial fibrosis were present in 85% and 87%, respectively. Mean resting tension and developed tension were 2.8±1 and 1.4±0.8 g/mm(2). On regression analysis, basal septal systolic strain, diastolic strain rate, disarray, and fibrosis were associated with developed tension (β=0.19, 0.20, -0.33, and -0.40, respectively, all P<0.01) and resting tension (β=0.21, 0.22, -0.25, and -0.28, respectively, all P<0.01).


CONCLUSIONS
In obstructive HCM patients who underwent SM, left ventricular mechanics (echocardiographic longitudinal systolic strain and diastolic strain rates), assessed at the basal septum (myocardium removed during myectomy) and histopathologic findings characteristic for HCM (disarray and fibrosis) were significantly associated with in vitro myocardial resting and developed contractile performance.
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Ashwat
A
Dhillon
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Wendy
W
Sweet
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Zoran B
ZB
Popovic
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Nicholas G
NG
Smedira
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Maran
M
Thamilarasan
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Bruce W
BW
Lytle
Pathology Institute, Cleveland Clinic, Cleveland, OH (C.T.).
Carmela
C
Tan
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Randall C
RC
Starling
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Harry M
HM
Lever
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Christine S
CS
Moravec
Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH (A.D., W.S., Z.B.P., N.G.S., M.T., B.W.L., R.C.S., H.M.L., C.S.M., M.Y.D.).
Milind Y
MY
Desai
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D001706:Biopsy; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D015150:Echocardiography, Doppler; D005260:Female; D005355:Fibrosis; D006346:Heart Septum / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000473:pathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013314:Stress, Mechanical; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D016277:Ventricular Function, Left; D014694:Ventricular Outflow Obstruction / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000601:surgery
HCM; contractile performance; histopathology; strain