Heterogeneity of ventricular function and myocardial oxidative metabolism in nonischemic dilated cardiomyopathy

Introduction: Dilated cardiomyopathy (DCM) is associated with impaired myocardial perfusion reserve and impaired myocardial oxidative metabolism. However, the association between myocardial perfusion reserve and oxidative metabolism, is not fully understood. Hypothesis: Reduced myocardial perfusion reserve is associated with reduced myocardial oxidative metabolism. Methods: Using non-invasive cardiac imaging, we studied 8 DCM patients and 14 normal subjects. Myocardial perfusion reserve index (MPRI) was calculated using cardiac magnetic resonance as the normalized rate of myocardial signal augmentation following gadolinium contrast injection between rest and regadenoson induced stress. Resting oxidative metabolism was calculated as the myocardial mono-exponential decay rate (Kmono) of [ 11 C]acetate by positron emission tomography normalized per unit demand (rate-pressure product, RPP) (Kmono/RPP). Results: MPRI was lower in DCM compared to controls (1.25 ± 0.22 vs 1.59 ± 0.49, p=0.038). Similarly, Kmono/RPP was lower in DCM compared with normal subjects (0.6x10e-3 ± 0.15 x10e-3 vs 1.2x10e-3 ± 0.9x10e-3, p<0.0001). There was a linear relation between Kmono and RPP in normal subjects. However, DCM patients showed no increase in Kmono regardless of RPP (Figure 1A). Kmono/RPP was not significantly related to MPRI in either group (Figure 1B). Conclusions: Patients with DCM exhibit markedly impaired myocardial oxidative metabolism compared to normal subjects. However, this impairment was not quantitatively related to impaired myocardial perfusion reserve. Of the various mechanisms that could explain decrease in oxidative metabolism in DCM, these data suggest that reduced myocardial perfusion is not the principal driver of impaired oxidative metabolism.

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P595Characteristics of the right ventricle in patients with nonischemic dilated cardiomyopathy

European Heart Journal ◽

10.1093/eurheartj/ehz747.0204 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

M Becker ◽

C P Allaart ◽

M Wubben ◽

J H Cornel ◽

A C Van Rossum ◽

...

Keyword(s):

Ejection Fraction ◽

Right Ventricular ◽

Dilated Cardiomyopathy ◽

Ventricular Function ◽

Left Atrial ◽

Systolic Dysfunction ◽

Underlying Mechanism ◽

Left Ventricular ◽

End Diastolic Volume ◽

Nonischemic Dilated Cardiomyopathy

Abstract Background In nonischemic dilated cardiomyopathy (DCM), diagnosis and prognosis is based on left ventricular function. Although concomitant right ventricular (RV) dysfunction is frequently observed, the underlying mechanism is currently not fully understood. Purpose We aimed to describe the characteristics of right ventricular function in DCM patients with cardiac magnetic resonance (CMR) imaging using cine and late-gadolinium enhancement (LGE) imaging. Methods Patients with DCM and left ventricular (LV) dysfunction (ejection fraction (EF) <50%) on LGE-CMR were included prospectively. LV and RV volumes and function were quantified and RV systolic dysfunction was defined as RV ejection fraction (RVEF)<45%. The presence and pattern of LGE were assessed visually and the extent was quantified using the full-width half maximum method. Septal midmyocardial LGE pattern was defined as midwall striae or hinge-point myocardial hyperenhancement. Moreover, left atrial (LA) volumes were calculated using the bi-plane area-length method. Results The study included 214 DCM patients (42% female, age 58±14 years) with a mean LVEF of 34±12% and RVEF of 46±12%. RV systolic dysfunction was present in 39% and was associated with the presence of septal midwall LGE (OR 1.96 (95% CI 1.09–3.54) p=0.026). In patients with RV dysfunction, LV dilation was more severe (LV end diastolic volume (EDV) 242±97mL vs. 212±58mL, p=0.011) and LVEF was lowere (26±12% vs. 39±8%, p<0.001) (figure A). There was a weak correlation between septal LGE amount and LVEDV and RVEDV (respectively r=0.36, p=0.003 and r=0.35, p=0.005) In patients with RV dysfunction, left atrial volumes were enlarged (56±23mL/m2 vs. 46±14mL/m2, p<0.001) and LA emptying fraction was moderately correlated to RVEF (figure B), also after exclusion of patients with a history of atrial fibrillation. RVEF in DCM patients Conclusion In DCM, reduced RVEF predominantly occurred in patients with a) LVEF lower than 30%, b) septal midwall enhancement, indicating progressive LV remodeling, c) LA dilation and d) LA dysfunction. This suggests that RV dysfunction in advanced DCM is drive by LV diastolic dysfunction resulting in increased afterload of the RV.

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