Cardiac work is related to creatine kinase energy supply in human heart failure: a cardiovascular magnetic resonance spectroscopy study

Abstract Background It has been hypothesized that the supply of chemical energy may be insufficient to fuel normal mechanical pump function in heart failure (HF). The creatine kinase (CK) reaction serves as the heart’s primary energy reserve, and the supply of adenosine triphosphate (ATP flux) it provides is reduced in human HF. However, the relationship between the CK energy supply and the mechanical energy expended has never been quantified in the human heart. This study tests whether reduced CK energy supply is associated with reduced mechanical work in HF patients. Methods Cardiac mechanical work and CK flux in W/kg, and mechanical efficiency were measured noninvasively at rest using cardiac pressure-volume loops, magnetic resonance imaging and phosphorus spectroscopy in 14 healthy subjects and 27 patients with mild-to-moderate HF. Results In HF, the resting CK flux (126 ± 46 vs. 179 ± 50 W/kg, p < 0.002), the average (6.8 ± 3.1 vs. 10.1 ± 1.5 W/kg, p  <0.001) and the peak (32 ± 14 vs. 48 ± 8 W/kg, p < 0.001) cardiac mechanical work-rates, as well as the cardiac mechanical efficiency (53% ± 16 vs. 79% ± 3, p < 0.001), were all reduced by a third compared to healthy subjects. In addition, cardiac CK flux correlated with the resting peak and average mechanical power (p < 0.01), and with mechanical efficiency (p = 0.002). Conclusion These first noninvasive findings showing that cardiac mechanical work and efficiency in mild-to-moderate human HF decrease proportionately with CK ATP energy supply, are consistent with the energy deprivation hypothesis of HF. CK energy supply exceeds mechanical work at rest but lies within a range that may be limiting with moderate activity, and thus presents a promising target for HF treatment. Trial registration ClinicalTrials.gov Identifier: NCT00181259

Determinants of label non-adherence to non-vitamin K oral anticoagulants in patients with newly diagnosed atrial fibrillation

AIMS: To evaluate the extent and determinants of off-label non-vitamin K oral anticoagulant (NOAC) dosing in newly diagnosed Dutch AF patients. METHODS AND RESULTS: In the DUTCH-AF registry, patients with newly diagnosed AF (<6 months) are prospectively enrolled. Label adherence to NOAC dosing was assessed using the European Medicines Agency labelling. Factors associated with off-label dosing were explored by multivariable logistic regression analyses. From July 2018 to November 2020, 4500 patients were registered. The mean age was 69.6 ± 10.5 years, and 41.5% were female. Of the 3252 patients in which NOAC label adherence could be assessed, underdosing and overdosing were observed in 4.2% and 2.4%, respectively. In 2916 (89.7%) patients with a full-dose NOAC recommendation, 4.6% were underdosed, with a similar distribution between NOACs. Independent determinants (with 95% confidence interval) were higher age [odds ratio (OR): 1.01 per year, 1.01-1.02], lower renal function (OR: 0.96 per ml/min/1.73 m(2), 0.92-0.98), lower weight (OR: 0.98 per kg, 0.97-1.00), active malignancy (OR: 2.46, 1.19-5.09), anaemia (OR: 1.73, 1.08-2.76), and concomitant use of antiplatelets (OR: 4.93, 2.57-9.46). In the 336 (10.3%) patients with a reduced dose NOAC recommendation, 22.9% were overdosed, most often with rivaroxaban. Independent determinants were lower age (OR: 0.92 per year, 0.88-0.96) and lower renal function (OR: 0.98 per ml/min/1.73 m(2), 0.96-1.00). CONCLUSION: In newly diagnosed Dutch AF patients, off-label dosing of NOACs was seen in only 6.6% of patients, most often underdosing. In this study, determinants of off-label dosing were age, renal function, weight, anaemia, active malignancy, and concomitant use of antiplatelets

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