L-Arginine Enhances the Effects of Cardiac Rehabilitation on Physical Performance: New Insights for Managing Cardiovascular Patients During the COVID-19 Pandemic.

Cardiac rehabilitation (CR) following acute myocardial infarction (AMI) improves physical capacities and decreases hospitalizations and cardiovascular mortality. L-arginine is the substrate used by nitric oxide (NO) synthase to generate NO and it has been shown to exert its beneficial effects on endothelium driving vasodilatation, reducing inflammation, and ameliorating physical function. We hypothesized that L-arginine could enhance physical capacities in patients who underwent CR after AMI. We designed a study aimed to assess the effects of L-arginine administration on the physical capacity of patients who underwent coronary revascularization after AMI. The trial was carried out amid the COVID-19 pandemic. Patients were assigned, with a 2:1 ratio, to add to their standard therapy one bottle containing 1.66 g of L-arginine or one bottle of identical aspect apart from not containing L-arginine, twice a day orally for 3 weeks. Patients performed a 6-minute walking test (6MWT), and their Borg modified 0-10 rating of perceived exertion (BRPE) was assessed before starting and at the end of the treatment. Seventy-five patients receiving L-arginine, and 35 receiving placebo successfully completed the study. The 6MWT distance increased significantly in the L-arginine group compared with both baseline and placebo (P < 0.0001). Additionally, we observed a significant improvement in the BRPE in patients treated with L-arginine but not in the placebo group. Taken together, our data indicate that L-arginine potentiates the response to CR independently of age, sex, baseline functional capacity, and comorbid conditions. SIGNIFICANCE STATEMENT: This study shows for the first time that oral supplementation of L-arginine potentiates the response to cardiac rehabilitation after myocardial infarction and cardiac revascularization. Indeed, we observed a significant improvement in two fundamental parameters, namely, the 6-minute walking test and the Borg modified 0-10 rating of perceived exertion. Strikingly, the beneficial effects of L-arginine were independent of age, sex, comorbid conditions, and baseline functional capacity.

Prediabetes Increases the Risk of Frailty in Prefrail Older Adults With Hypertension: Beneficial Effects of Metformin.

BACKGROUND: Prediabetes has garnered increasing attention due to its association with cardiovascular conditions, especially hypertension, which heightens the risk of prefrailty and frailty among older individuals. METHODS: We screened elders with prefrail hypertension from March 2021 to January 2023. We assessed the correlation linking cognitive dysfunction (Montreal Cognitive Assessment score), insulin resistance (triglyceride-to-glucose index), and physical impairment (5-meter gait speed). Then, we measured the risk of developing frailty after a 1-year follow-up period, adjusting the outcome using multivariable Cox regression analysis. We also investigated the impact of administering 500 mg of metformin once daily to a subset of frail subjects for an additional 6 months. RESULTS: We assessed the relationship between the triglyceride-to-glucose index and the Montreal Cognitive Assessment score, observing a significant correlation (r, 0.880; P<0.0001). Similarly, we analyzed the association between the triglyceride-to-glucose index and 5-meter gait speed, uncovering a significant link between insulin resistance and physical impairment (r, 0.809; P<0.0001). Prediabetes was found to significantly (P<0.0001) elevate the risk of frailty development compared with individuals without prediabetes by the end of the 1-year follow-up, a finding confirmed via multivariable analysis with Cox regression. Furthermore, among the subgroup of subjects who developed frailty, those who received metformin exhibited a significant decrease in frailty levels (P<0.0001). CONCLUSIONS: Insulin resistance and prediabetes play substantial roles in the development of cognitive and physical impairments, highlighting their importance in managing hypertension, even before the onset of frank diabetes. Metformin, a well-established drug for the treatment of diabetes, has shown favorable effects in mitigating frailty.

Very low protein diet reduces indoxyl sulfate levels in chronic kidney disease.

BACKGROUND AND OBJECTIVES: High levels of indoxyl sulfate (IS) are associated with chronic kidney disease (CKD) progression and increased mortality in CKD patients. The aim of this pilot study was to assess whether a very low protein diet (VLPD; 0.3 g/kg bw/day), with a consequent low phosphorus intake, would reduce IS serum levels compared to a low protein diet (LPD; 0.6 g/kg bw/day) in CKD patients not yet on dialysis. MATERIAL AND METHODS: This is a post hoc analysis of a preceding cross-over study aimed to analyze FGF23 during VLPD. Here we performed a prospective randomized controlled crossover study in which 32 patients were randomized to receive either a VLPD (0.3 g/kg bw/day) supplemented with ketoanalogues during the first week and an LPD during the second week (group A, n = 16), or an LPD during the first week and a VLPD during the second week (group B, n = 16 patients). IS serum levels were measured at baseline and at the end of each study period. We compared them to 24 hemodialysis patients (HD) and 14 healthy subjects (control). RESULTS: IS serum concentration was significantly higher in the HD (43.4 ± 12.3 µM) and CKD (11.1 ± 6.6 µM) groups compared to the control group (2.9 ± 1.1 µM; p < 0.001). IS levels also correlated with creatinine values in CKD patients (R(2) = 0.42; p < 0.0001). After only 1 week of a VLPD, even preceded by an LPD, CKD patients showed a significant reduction of IS serum levels (37%). CONCLUSIONS: VLPD supplemented with ketoanalogues reduced IS serum levels in CKD patients not yet on dialysis.

Daily dialysis reduces pulse wave velocity in chronic hemodialysis patients.

Pulse wave velocity (PWV) is a predictor of morbidity and mortality in patients with end-stage renal disease (ESRD). Dialysis patients show cyclic changes in PWV related to their hydration status and blood pressure. Our aim is to assess the impact of daily dialysis on PWV. We performed a randomized crossover study of 60 patients who underwent standard hemodialysis (HD) three times per week for at least 6 months. Patients were classified into three groups according to their PWV values before (pre-) and after (post-) HD, with a cutoff value of 12 m s(-1), as follows: the low-low (LL) group had normal pre-HD and post-HD PWV; the high-low (HL) group had high pre-HD PWV and normal post-HD PWV; and the high-high (HH) group had high pre- and post-HD PWV. All patients continued standard HD for 2 weeks. A total of 10 patients from each group were randomly assigned to continue standard HD for 1 week and then underwent daily dialysis for 1 week. The remaining 10 patients underwent daily dialysis for 1 week and then underwent standard HD for 1 week. PWV values were measured before and 1 h after each dialysis session. With daily dialysis treatment, 2 of 20 patients (10%) moved from the PWV-HH group to the PWV-HL group, whereas 18 of 20 patients (90%) moved from the PWV-HL group to the PWV-LL group (P = 0.030). Daily dialysis reduces PWV in the ESRD patients. As PWV is a strong predictor of mortality in ESRD and has cyclic variations in patients who are on standard HD, we believe that daily dialysis may be used in patients with high PWV levels to reduce their mortality risk.

Dialysate bath and QTc interval in patients on chronic maintenance hemodialysis: pilot study of single dialysis effects.

INTRODUCTION: Serum concentrations of potassium (K) and calcium (Ca) influence ionic currents and play an important role in the duration of ventricular action potential. Further, the influence of alkalosis in reducing ionized calcium has been well known for a long time. The aim of this study was to assess the effects of different dialysate electrolytes and bicarbonate concentrations on changes of QTc interval in patients on chronic hemodialysis. METHODS: The study hemodialysis sessions were performed in 22 patients, with different electrolyte and bicarbonate concentrations in dialysate. Tested dialysate concentrations were K of 2 and 3 mmol/L; Ca 1.25, 1.5 and 1.75 mmol/L; and bicarbonate 30 and 34 mmol/L. An electrocardiogram (ECG) was recorded 1 hour before, at the end and every hour for 4 hours after each study dialysis session. QTc interval was measured from the beginning of the QRS complex to the end of a T wave on a 12-lead ECG. Blood was collected and K, total Ca, ionic Ca and pH evaluated. RESULTS: At the end of the study hemodialysis session with dialysate containing low K (2 mmol/L), low Ca (1.25 mmol/L) and high bicarbonate concentration (34 mmol), mean QTc interval was significantly prolonged compared with that recorded with dialysate containing high K (3 mmol/L), high Ca (1.75 mmol/L) and bicarbonate (30 mmol) (40 ± 10 milliseconds vs. 2 ± 2 milliseconds; p<0.01). Dialysate with low concentration of low Ca, K and high concentration of bicarbonate was an independent predictor of QTc; the combination of low Ca and K and high bicarbonate strongly increased the risk of prolonged QTc interval. CONCLUSION: The present pilot study shows that changes in QTc interval during hemodialysis depend on both electrolyte and bicarbonate concentrations in dialysate.