Determinants of myocardial energetics and efficiency in symptomatic hypertrophic cardiomyopathy.
OBJECTIVE
Next to hypertrophy, hypertrophic cardiomyopathy (HCM) is characterized by alterations in myocardial energetics. A small number of studies have shown that myocardial external efficiency (MEE), defined by external work (EW) in relation to myocardial oxidative metabolism (MVO(2)), is reduced. The present study was conducted to identify determinants of MEE in patients with HCM by use of dynamic positron emission tomography (PET) and cardiovascular magnetic resonance imaging (CMR).


METHODS
Twenty patients with HCM (12 men, mean age: 55.2 + or - 13.9 years) and 11 healthy controls (7 men, mean age: 48.1 + or - 10 years) were studied with [(11)C]acetate PET to assess MVO(2). CMR was performed to determine left ventricular (LV) volumes and mass (LVM). Univariate and multivariate analyses were employed to determine independent predictors of myocardial efficiency.


RESULTS
Between study groups, MVO(2) (controls: 0.12 + or - 0.04 ml x min(-1) x g(-1), HCM: 0.13 + or - 0.05 ml x min(-1) x g(-1), p = 0.64) and EW (controls: 9,139 + or - 2,484 mmHg x ml, HCM: 9,368 + or - 2,907 mmHg x ml, p = 0.83) were comparable, whereas LVM was significantly higher (controls: 99 + or - 21 g, HCM: 200 + or - 76 g, p < 0.001) and MEE was decreased in HCM patients (controls: 35 + or - 8%, HCM: 21 + or - 10%, p < 0.001). MEE was related to stroke volume (SV), LV outflow tract gradient, NH(2)-terminal pro-brain natriuretic peptide (NT-proBNP) and serum free fatty acid levels (all p < 0.05). Multivariate analysis revealed that SV (ss = 0.74, p < 0.001) and LVM (ss = -0.43, p = 0.013) were independently related to MEE.


CONCLUSIONS
HCM is characterized by unaltered MVO(2), impaired EW generation per gram of myocardial tissue and subsequent deteriorated myocardial efficiency. Mechanical external efficiency could independently be predicted by SV and LVM.
Timmer
Stefan A J
SA
Department of Cardiology, 5F, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands.
Germans
Tjeerd
T
Götte
Marco J W
MJ
Rüssel
Iris K
IK
Dijkmans
Pieter A
PA
Lubberink
Mark
M
ten Berg
Jurrien M
JM
ten Cate
Folkert J
FJ
Lammertsma
Adriaan A
AA
Knaapen
Paul
P
van Rossum
Albert C
AC
D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D018619:Echocardiography, Doppler, Pulsed; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000503:physiopathology; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010101:Oxygen Consumption; D049268:Positron-Emission Tomography; D014694:Ventricular Outflow Obstruction / Q000503:physiopathology