Background Diagnosis of early heart failure with preserved ejection fraction (HFpEF) may be challenging because exertional dyspnea is not specific for heart failure, and biomarkers and indicators of volume overload may be absent at rest. We aimed to characterize the contribution of abnormal left atrial (LA) mechanical properties to exercise intolerance in early HFpEF (normal left ventricular filling pressures at rest but elevated during exercise). Methods Diastolic stress testing (DST) was performed in 104 patients with left ventricular ejection fraction ≥50%, in sinus rhythm, and no more than LV diastolic dysfunction grade I, referred for assessment of exertional dyspnoea. Patients exercised supine cycle ergometry at 60 rpm starting with a 3-min period of low-level 25-W workload followed by 25-W increments in 3-minute stages to maximum tolerated levels. According to DST, 43 patients were diagnosed with HFpEF (average mitral E-to-annular e′ ratio [E/e′] > 14, and peak TR velocity >2.8 m/sec at maximal exertion) and 61 as non-cardiac dyspnea (NCD). During the test, two-dimensional images, mitral E/e′, peak tricuspid regurgitation (TR) velociry, and two-dimensional LA mechanical parameters (longitudinal LA strain [LASR] and strain rate [LASRR] during reservoir phase and LA stiffness assessed as a ratio of mitral E/e′ ratio to LASR) were analysed at baseline, and at peak. Results HFpEF and NCD patients were similar in regard to the LA volume index (34.4 [30.2;39.4] vs. 33.6 [28.4;37.1] ml/m2), and NT-proBNP level (132 [80;238] vs. 129 [80;197] pg/ml). As compared with NCD patients, HFpEF patients displayed reduced LA reservoir function assessed by LASR (22.3 [18.9;25.6] vs. 24.2 [21.2;29.8] % at rest, and 25.3 [21.4;30.2] vs. 29.0 [24.2;33.3] % with exercise) and LASRR (0.78 [0.58;0.96] vs. 0.90 [0.68;1.12] /s at rest, and 1.10 [0.79;1.31] vs. 1.24 [1.03;1.56] s–1 with exercise) with increased LA stiffness (0.57 [0.44;0.70] vs. 0.42 [0.30;0.49] mmHg/% at rest, and 0.61 [0.46;0.74] vs. 0.40 [0.32;0.51] mmHg/% with exercise, all P < 0.05). Additionally, HFpEF patients showed smaller exercise elevation in LASRR (+31 [-5;77] vs. +47 [12;85] % as compared with resting values, P < 0.05). Exercised LA stiffness and reservoir strain correlated with exercise LV filling pressures estimated by mitral E/e′ ratio (r = 0.72 and r =–0.35, P < 0.001). LA stiffness showed a good diagnostic accuracy (area under the curve 0.75), and LA stiffness > 0.46 mmHg/% demonstrated reasonable sensitivity (79%) and specificity (71%) to diagnose HFpEF. Neither LV global longitudinal strain and ejection fraction at rest nor their exercise-induced elevation differed between HFpEF and NCD. Conclusion Impaired LA reservoir function and increased stiffness are associated with exercise intolerance in patients with early HFpEF, while LV systolic function seems preserved in this stage of the disease. LA stiffness provides HFpEF diagnostic potential in ambulatory patients with dyspnea
Clinical and hemodynamic aggravation of heart failure with preserved ejection fraction (HFpEF) is largely due to progression of left ventricular (LV) diastolic dysfunction. The key role in the normal maintenance of diastolic function is played by a high level of activity of the intracellular signaling axis, cyclic guanosine-monophosphate-protein kinase G, the activity of which is significantly reduced in HFpEF. The activity of this axis can be increased by increasing the bioavailability of natriuretic peptides by blocking the enzyme neutral endopeptidase (neprilisin), which is responsible for the destruction of natriuretic peptides.This review presents experimental and clinical data on the use of neprilysin inhibitors in HFpEF and addresses prospects of this treatment.
The aim of the study was to explore the Klotho protein significance in patients with different stages of chronic kidney disease (CKD) and to assess the influence of antihypertensive therapy on Klotho protein serum levels. Materials and methods. 130 patients with stage 5 CKD1 were included in the study. Serum PTH, calcium and phosphorus were measured. ELISA was used to determine serum soluble alpha Klotho. Blood pressure including brachial and central (aortic) pressure was measured in all patients together with pulse wave velocity (using a «Sfigmokor» device); in addition, echocardiography (EchoCG), and X-ray examination of the abdominal aorta by Kauppila method were performed. Results. The dynamic study of serum Klotho level showed that it changes with decreasing glomerular filtration rate faster than a rise in phosphate and PTH levels starting from stage 3A of CKD. The two later variables increased at stages 4-5.According to the ROC analysis, the values of serum Klotho below 387 pg /ml suggested enhanced risk of myocardial calcification with 80% sensitivity and 76% specificity. In addition, the highest Klotho serum levels were observed in patients whose target BP values were achieved with angiotensin receptor blockers (ARB) compared to those who used other drugs [р<0,01] or failed to reached target BP levels [p=0,008]. Сonclusion. The study showed the possibility of practical use of Klotho protein as an early diagnostic marker of cardiovascular risk. Reduced serum Klotho was less pronounced in patients who used ARB for correction of high blood pressure. Normal Klotho protein levels in serum have been associated with a lower frequency of heart and vessels calcification in CKD patients.
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