Low serum potassium levels and diabetes - An unfavorable combination in patients with heart failure and preserved ejection fraction

J-shaped association between serum glucose potassium ratio and prognosis in heart failure with preserved ejection fraction with stronger predictive value in non-diabetic patients

BACKGROUND

The relationship between serum glucose/potassium ratio (GPR) and the adverse outcomes in patients with heart failure with preserved ejection fraction (HFpEF) has not been completely clarified.

METHODS

Patients were included from the American cohort of the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial. The primary endpoint was the composite of cardiovascular mortality, aborted cardiac arrest, and hospitalization for HF. The Cox regression models were applied to calculate the hazard ratio (HR) and 95% confidence interval (CI) to examine the relationship between GPR and prognosis. Restricted cubic spline (RCS) curves were performed to explore the nonlinear relationship between GPR and the primary endpoint. Receiver Operating Characteristic (ROC) curves were constructed, and the areas under the curves (AUCs) for GPR and its components were compared using the DeLong test. Subgroup analysis and interaction effect were also explored.

RESULTS

A total of 1749 HFpEF patients were included. During the follow-up, 514 (29.4%) patients reached the primary outcome. An increase in GPR was independently associated with a higher risk in the primary endpoint [Tertile 3 vs. Tertile 1: HR (95% CI), 1.35 (1.07-1.70), P = 0.012] and HF hospitalization [Tertile 3 vs. Tertile 1: HR (95% CI), 1.57 (1.20-2.05), P = 0.001]. RCS curve showed a J-shape trend between GPR and primary endpoint (non-linear P = 0.002). The AUC for GPR was superior to that of the glucose and potassium (De long test P < 0.05). Additionally, the prognostic value of GPR was stronger in patients without diabetes and with less severe heart failure symptoms (P interaction < 0.05).

CONCLUSION

A J-shaped relationship was existed between GPR levels and the primary outcome in HFpEF patients. An increased GPR was an independent predictor of poor prognosis in HFpEF patients, especially in non-diabetic patients and those with less severe heart failure symptoms.

Hypokalemia in Diabetes Mellitus Setting

Diabetes mellitus is a public health problem that affects millions of people worldwide regardless of age, sex, and ethnicity. Electrolyte disturbances may occur as a consequence of disease progression or its treatment, in particular potassium disorders. The prevalence of hypokalemia in diabetic individuals over 55 years of age is up to 1.2%. In patients with acute complications of diabetes, such as diabetic ketoacidosis, this prevalence is even higher. Potassium disorders, either hypokalemia or hyperkalemia, have been associated with increased all-cause mortality in diabetic individuals, especially in those with associated comorbidities, such as heart failure and chronic kidney disease. In this article, we discuss the main conditions for the onset of hypokalemia in diabetic individuals, briefly review the pathophysiology of acute complications of diabetes mellitus and their association with hypokalemia, the main signs, symptoms, and laboratory parameters for the diagnosis of hypokalemia, and the management of one of the most common electrolyte disturbances in clinical practice.

High-Accuracy Determination of Potassium and Selenium in Human Serum by Two-Step Isotope Dilution ICPMS

A high-accuracy measurement technique for determining potassium and selenium in human serum was developed by using two-step Isotope Dilution Inductively Coupled Plasma-Mass Spectrometry (ICPMS) in this research. A more accessible method of the quadrupole ICPMS was employed in this research to achieve an equally high accuracy which had been achieved by a much more expensive method, namely, high-resolution sector field ICPMS (SF-ICPMS), with a comparatively easy and simple operation. In addition, we have evaluated the uncertainty of this method. The results showed that the determination limits of potassium and selenium in serum were 0.8 mg/kg and 2.7 μg/kg, respectively, and the precision for both measurements was lower than 0.2% and 0.7%. The measurement, when employed to measure potassium and selenium in standard materials NIST956D, NIST909C, and GBW09152, had caused a maximum deviation of less than 0.9%, within the stated uncertainty range of standard materials. The RELA international inter-laboratory comparisons of potassium in serum in 2018 conducted by our laboratory also yielded a satisfactory result.

Serum potassium and outcomes in heart failure with preserved ejection fraction: a post-hoc analysis of the PARAGON-HF trial

AIMS

The relationship between serum potassium concentration and outcomes in patients with heart failure and preserved ejection fraction (HFpEF) is not well-established. The aim of this study was to explore the association between serum potassium and clinical outcomes in the PARAGON-HF trial in which 4822 patients with HFpEF were randomised to treatment with sacubitril/valsartan or valsartan.

METHODS AND RESULTS

The relationship between serum potassium concentrations and the primary study composite outcome of total (first and recurrent) heart failure hospitalisations and cardiovascular death was analysed. Hypo-, normo-, and hyperkalaemia were defined as serum potassium <4 mmol/L, 4-5 mmol/L and >5 mmol/L, respectively. Both screening and time-updated potassium (categorical and continuous spline-transformed) were studied. Patient mean age was 73 years and 52% were women. Patients with higher baseline potassium more often had an ischaemic aetiology and diabetes and mineralocorticoid receptor antagonist treatment. Compared with normokalaemia, both time-updated (but not screening) hypo- and hyperkalaemia were associated with a higher risk of the primary outcome [adjusted hazard ratio (HR) for hypokalaemia 1.55, 95% confidence interval (CI) 1.30-1.85; P < 0.001, and for hyperkalaemia HR 1.21, 95% CI 1.02-1.44; P = 0.025]. Hypokalaemia had a stronger association with a higher risk of all-cause, cardiovascular and non-cardiovascular death than hyperkalaemia. The association of hypokalaemia with increased risk of all-cause and cardiovascular death was most marked in participants with impaired kidney function (interaction P < 0.05). Serum potassium did not significantly differ between sacubitril/valsartan and valsartan throughout the follow-up.

CONCLUSIONS

Both hypo- and hyperkalaemia were associated with heart failure hospitalisation but only hypokalaemia was associated with mortality, especially in the context of renal impairment. Hypokalaemia was as strongly associated with death from non-cardiovascular causes as with cardiovascular death. Collectively, these findings suggest that potassium disturbances are a more of a marker of HFpEF severity rather than a direct cause of death.