Patterns of chronic and transient hyperkalaemia and clinically important outcomes in patients with chronic kidney disease

Epidemiology and risk factors for hyperkalaemia in heart failure

Patients with heart failure (HF), particularly those with impaired renal function receiving renin-angiotensin-aldosterone system inhibitors (RAASis), are at risk of hyperkalaemia; when hyperkalaemia is severe, this can have serious clinical consequences. The incidence, prevalence, and risk factors for hyperkalaemia reported in randomized trials of RAASis may not reflect clinical practice due to exclusion of patients with elevated serum potassium (sK+ ) or severe renal impairment: information on patients managed in routine clinical care is important to understanding the actual burden of hyperkalaemia. This paper reviews the available clinical epidemiology data on hyperkalaemia in HF and considers areas requiring further research. Observational studies published since 2017 that focused on hyperkalaemia, included patients with HF, and had ≥1000 participants were considered. Hyperkalaemia occurrence in HF varied widely from 7% to 39% depending on the setting, HF severity, follow-up length, and concomitant medications. Rates were lowest in patients with newly diagnosed HF and highest in patients with greater disease severity; comorbidities, such as chronic kidney disease and diabetes, and RAASi use, reflected commonly identified risk factors for hyperkalaemia in patients with HF. Hyperkalaemia was most often mild; however, from the limited data available, persistence of mild hyperkalaemia was associated with an increased risk of mortality and major adverse cardiovascular events. There were also limited data available on the progression of hyperkalaemia. Recurrence was common, occurring in one-quarter to two-fifths of hyperkalaemia cases. Despite HF guidelines recommending close monitoring of sK+ , 55-93% of patients did not receive appropriate testing before or after initiation of RAASi or in follow-up to moderate/severe hyperkalaemia detection. Many of the observational studies were retrospective and from a single country. There is a need for international, prospective, longitudinal, observational studies, such as the CARE-HK in HF study (NCT04864795), to understand hyperkalaemia's prevalence, incidence, and severity; to identify and characterize cases that persist, progress, and recur; to highlight the importance of sK+ monitoring when using RAASi; and to assess the impact of newer HF therapies and potassium binders in clinical practice. Data from both clinical trials and observational studies with adjustments for confounding variables will be needed to assess the contribution of hyperkalaemia to clinical outcomes.

Practical patient care appraisals with use of new potassium binders in heart failure and chronic kidney diseases

Hyperkalaemia is a life-threatening condition leading to significant morbidity and mortality. It is common in heart failure and in chronic kidney disease (CKD) patients due to the diseases themselves, which often coexist, the high co-presence of diabetes, the fluctuations in renal function, and the use of some drugs [i.e. renin-angiotensin-aldosterone system (RAAS) inhibitors]. Hyperkalaemia limits their administration or uptitration, thus impacting on mortality. New K + binders, namely patiromer and sodium zirconium cyclosilicate (ZS-9), are an intriguing option to manage hyperkalaemia in heart failure and/or CKD patients, both to reduce its fatal effects and to let clinicians uptitrate RAAS inhibition. Even if their real impact on strong outcomes is still to be determined, we hereby provide a practical approach to favour their use in routine clinical practice in order to gain the correct confidence and provide an additive tool to heart failure and CKD patients' wellbeing. New trials are welcome to fill the gap in knowledge.

Serum Potassium and Risk of Death or Kidney Replacement Therapy in Older People With CKD Stages 4-5: Eight-Year Follow-up

RATIONALE & OBJECTIVE

Hypokalemia may accelerate kidney function decline. Both hypo- and hyperkalemia can cause sudden cardiac death. However, little is known about the relationship between serum potassium and death or the occurrence of kidney failure requiring replacement therapy (KRT). We investigated this relationship in older people with chronic kidney disease (CKD) stage 4-5.

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

We followed 1,714 patients (≥65 years old) from the European Quality (EQUAL) study for 8 years from their first estimated glomerular filtration rate (eGFR)<20mL/min/1.73m2 measurement.

EXPOSURE

Serum potassium was measured every 3 to 6 months and categorized as≤3.5,>3.5-≤4.0,>4.0-≤4.5,>4.5-≤5.0 (reference),>5.0-≤5.5, >5.5-≤6.0, and>6.0mmol/L.

OUTCOME

The combined outcome death before KRT or start of KRT.

ANALYTICAL APPROACH

The association between categorical and continuous time-varying potassium and death or KRT start was examined using Cox proportional hazards and restricted cubic spline analyses, adjusted for age, sex, diabetes, cardiovascular disease, renin-angiotensin-aldosterone system (RAAS) inhibition, eGFR, and subjective global assessment (SGA).

RESULTS

At baseline, 66% of participants were men, 42% had diabetes, 47% cardiovascular disease, and 54% used RAAS inhibitors. Their mean age was 76±7 (SD) years, mean eGFR was 17±5 (SD) mL/min/1.73m2, and mean SGA was 6.0±1.0 (SD). Over 8 years, 414 (24%) died before starting KRT, and 595 (35%) started KRT. Adjusted hazard ratios for death or KRT according to the potassium categories were 1.6 (95% CI, 1.1-2.3), 1.4 (95% CI, 1.1-1.7), 1.1 (95% CI, 1.0-1.4), 1 (reference), 1.1 (95% CI, 0.9-1.4), 1.8 (95% CI, 1.4-2.3), and 2.2 (95% CI, 1.5-3.3). Hazard ratios were lowest at a potassium of about 4.9mmol/L.

LIMITATIONS

Shorter intervals between potassium measurements would have allowed for more precise estimations.

CONCLUSIONS

We observed a U-shaped relationship between serum potassium and death or KRT start among patients with incident CKD 4-5, with a nadir risk at a potassium level of 4.9mmol/L. These findings underscore the potential importance of preventing both high and low potassium in patients with CKD 4-5.

PLAIN-LANGUAGE SUMMARY

Abnormal potassium blood levels may increase the risk of death or kidney function decline, especially in older people with chronic kidney disease (CKD). We studied 1,714 patients aged≥65 years with advanced CKD from the European Quality (EQUAL) study and followed them for 8 years. We found that both low and high levels of potassium were associated with an increased risk of death or start of kidney replacement therapy, with the lowest risk observed at a potassium level of 4.9 mmol/L. In patients with CKD, the focus is often on preventing high blood potassium. However, this relatively high optimum potassium level stresses the potential importance of also preventing low potassium levels in older patients with advanced CKD.

Intensity of and Adherence to Lipid-Lowering Therapy as Predictors of Major Adverse Cardiovascular Outcomes in Patients With Coronary Heart Disease

Background The effectiveness of lipid-lowering therapy (LLT) is affected by both intensity and adherence. This study evaluated the associations of LLT intensity, adherence, and the combination of these 2 aspects of LLT management with the risk of major adverse cardiovascular events (MACE) in people with coronary heart disease. Methods and Results This is an observational study of all adults who suffered a myocardial infarction or had coronary revascularization during 2012 to 2018 and initiated LLT in Stockholm, Sweden. Study exposures were LLT adherence (proportion of days covered), LLT intensity (expected reduction of low-density lipoprotein cholesterol), and the combined measure of adherence and intensity. At each LLT fill, adherence and intensity during the previous 12 months were calculated. The primary outcomes were MACE (nonfatal myocardial infarction or stroke and death); secondary outcomes were low-density lipoprotein cholesterol goal attainment and individual components of MACE. We studied 20 490 patients aged 68±11 years, 75% men, mean follow-up 2.6±1.1 years. Every 10% increase in 1-year adherence, intensity, or adherence-adjusted intensity was associated with a lower risk of MACE (hazard ratio [HR], 0.94 [95% CI, 0.93-0.96]; HR, 0.92 [95% CI, 0.88-0.96]; and HR, 0.91 [95% CI, 0.89-0.94], respectively) and higher odds of attaining low-density lipoprotein cholesterol goals (odds ratio [OR],1.12 [95% CI, 1.10-1.15]; OR, 1.42 [95% CI, 1.34-1.51], and OR, 1.16 [95% CI, 1.19-1.24], respectively). Among patients with good adherence (≥80%), the risk of MACE was similar with low-moderate and high-intensity LLT despite differences in the low-density lipoprotein cholesterol goal attainment with the treatment intensities. Discontinuation ≥1 year increased the risk markedly (HR,1.66 [95% CI, 1.23-2.22]). Conclusions In routine care, good adherence to LLT was associated with the greatest benefit for patients with coronary heart disease. Strategies that improve adherence and use of intensive therapies could substantially reduce cardiovascular risk.

Stopping renin-angiotensin system inhibitors after hyperkalemia and risk of adverse outcomes

BACKGROUND

Stopping renin-angiotensin system inhibitors (RASi) after an episode of hyperkalemia is common but may involve therapeutic compromises, in that the cessation of RASi deprives patients of their beneficial cardiovascular effects.

METHODS AND RESULTS

Observational study from the Stockholm Creatinine Measurements (SCREAM) project including patients initiating RASi in routine care and surviving a first-detected episode of hyperkalemia (potassium >5.0 mmol/L). We used target trial emulation techniques based on cloning, censoring and weighting to compare stopping vs. continuing RASi within 6 months after hyperkalemia. Outcomes were 3-year risks of mortality, major adverse cardiovascular events (MACE, composite of cardiovascular death, myocardial infarction and stroke hospitalization) and recurrent hyperkalemia. Of 5669 new users of RASi who developed hyperkalemia (median age 72 years, 44% women), 1425 (25%) stopped RASi therapy within 6 months. Compared with continuing RASi, stopping therapy was associated with a higher 3-year risk of death (absolute risk difference 10.8%; HR 1.49, 95% CI 1.34-1.64) and MACE (risk difference 4.7%; HR 1.29, 1.14-1.45), but a lower risk of recurrent hyperkalemia (risk difference -9.5%; HR 0.76, 0.69-0.84). Results were consistent for events following potassium of >5.0 or >5.5 mmol/L, after censoring when the treatment decision was changed, across prespecified subgroups, and after adjusting for albuminuria.

CONCLUSION

These findings suggest that stopping RASi after hyperkalemia may be associated with a lower risk of recurrence of hyperkalemia, but higher risk of death and cardiovascular events.

Stopping mineralocorticoid receptor antagonists after hyperkalaemia: trial emulation in data from routine care

AIMS

Whether to continue or stop mineralocorticoid receptor antagonists (MRA) after an episode of hyperkalaemia is a challenge in clinical practice. While stopping MRA may prevent recurrent hyperkalaemias, it deprives patients of their cardioprotection. We here assessed the association between stopping vs. continuing MRA therapy after hyperkalaemia and the subsequent risks of adverse health events.

METHODS AND RESULTS

Observational study from the Stockholm CREAtinine Measurements (SCREAM) project 2006-2018. We identified patients initiating MRA and surviving a first-detected episode of hyperkalaemia (plasma potassium >5.0 mmol/L). Using target trial emulation methods, we assessed the association between stopping vs. continuing MRA within 6 months after hyperkalaemia and subsequent outcomes. The primary outcome was the composite of hospital admission with heart failure, stroke, myocardial infarction, or death. The secondary outcome was occurrence of another hyperkalaemia event. Among 39 518 patients initiating MRA, we identified 7366 who developed hyperkalaemia. Median age was 76 years, 45% were women and 69% had a history of heart failure. Following hyperkalaemia, 2222 (30%) discontinued treatment. Compared with continuing MRA, stopping therapy was associated with a lower 2-year risk of recurrent hyperkalaemia [hazard ratio (HR) 0.75, 95% confidence interval (CI) 0.72-0.79], but a higher risk of the primary outcome (HR 1.10, 95% CI 1.06-1.14). Similar results were observed in patients with heart failure, after censoring when treatment decision was changed, and across pre-specified subgroups.

CONCLUSIONS

Stopping MRA after an episode of hyperkalaemia was associated with reduced risk for recurrent hyperkalaemia, but higher risk of death or cardiovascular events. Recurrent hyperkalaemia was common in either strategy.