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Aims Myocardial external efficiency (MEE) is the ratio of cardiac work in relation with energy expenditure. We studied MEE in patients with different aetiologies and stages of heart failure (HF) to discover the role and causes of deranged MEE. In addition, we explored the impact of patient characteristics such as sex, body mass index (BMI), and age on myocardial energetics. Methods and results Cardiac energetic profiles were assessed with 11C-acetate positron emission tomography (PET) and left ventricular ejection fraction (LVEF) was acquired with echocardiography. MEE was studied in 121 participants: healthy controls (n  = 20); HF patients with reduced (HFrEF; n  = 25) and mildly reduced (HFmrEF; n  = 23) LVEF; and patients with asymptomatic (AS-asymp; n  = 38) and symptomatic (AS-symp; n  = 15) aortic stenosis (AS). Reduced MEE coincided with symptoms of HF irrespective of aetiology and declined in tandem with deteriorating LVEF. Patients with AS-symp and HFmrEF had reduced MEE as compared with controls (22.2 ± 4.9%, P  = 0.041 and 20.0 ± 4.2%, P  < 0.001 vs. 26.1 ± 5.8% in controls) and a further decline was observed in patients with HFrEF (14.7 ± 6.3%, P  < 0.001). Disproportionate left ventricular hypertrophy was a major cause of reduced MEE. Female sex (P  < 0.001), a lower BMI (P  = 0.001), and advanced age (P  = 0.03) were associated with a lower MEE. Conclusion MEE was reduced in patients with HFrEF, HFmrEF, and HF due to pressure overload and MEE may therefore constitute a treatment target in HF. Patients with LVH, advanced age, female sex, and low BMI had more pronounced reduction in MEE and personalized treatment within these patient subgroups could be relevant. [ABSTRACT FROM AUTHOR]

Aims Left ventricular filling pressure (preload) can be assessed by pulmonary capillary wedge pressure (PCWP) during pulmonary arterial catheterization (PAC). An emerging method [pulse indexed contour cardiac output (PICCO)] can estimate preload by global end-diastolic volume (GEDV) and congestion as extravascular lung water (EVLW) content. However, no reliable quantitative non-invasive methods are available. Hence, in a porcine model of pulmonary congestion, we evaluated EVLW and GEDV by positron emission tomography (PET). The method was applied in 35 heart failure (HF) patients and 9 healthy volunteers. Methods and results Eight pigs were studied. Pulmonary congestion was induced by a combination of beta-blockers, angiotensin-2 agonist and saline infusion. PAC, PICCO, computerized tomography, and 15O-H2O-PET were performed. EVLW increased from 521 ± 76 to 973 ± 325 mL (P  < 0.001) and GEDV from 1068 ± 170 to 1254 ± 85 mL (P  < 0.001). 15O-H2O-PET measures of EVLW increased from 566 ± 151 to 797 ± 231 mL (P  < 0.001) and GEDV from 364 ± 60 to 524 ± 92 mL (P  < 0.001). Both EVLW and GEDV measured with PICCO and 15O-H2O-PET correlated (r 2 = 0.40, P  < 0.001; r 2 = 0.40, P  < 0.001, respectively). EVLW correlated with Hounsfield units (HU; PICCO: r 2 = 0.36, P  < 0.001, PET: r 2 = 0.46, P  < 0.001) and GEDV with PCWP (PICCO: r 2 = 0.20, P  = 0.01, PET: r 2 = 0.29, P  = 0.002). In human subjects, measurements were indexed (I) for body surface area. Neither EVLWI nor HU differed between chronic stable HF patients and healthy volunteers (P  = 0.11, P  = 0.29) whereas GEDVI was increased in HF patients (336 ± 66 mL/m2 vs. 276 ± 44 mL/m2, P  = 0.01). Conclusion The present study demonstrates that 15O-H2O-PET can assess pulmonary congestion and preload quantitatively. Hence, prognostic information from 15O-H2O-PET examinations should be evaluated in clinical trials. [ABSTRACT FROM AUTHOR]