Sudden cardiac death in chronic renal disease: aetiology and risk reduction strategies

Impact of Chronic Kidney Disease on the Processes of Care and Long-Term Mortality of Non-ST-Segment-Elevation Myocardial Infarction: A Nationwide Cohort Study and Long-Term Follow-Up

BACKGROUND

A growing population of patients with chronic kidney disease (CKD) presents with non-ST-segment-elevation myocardial infarction, although little is known about their longer-term mortality.

METHODS AND RESULTS

Using the MINAP (Myocardial Ischaemia National Audit Project) registry, linked to Office for National Statistics mortality data, we analyzed 363 559 UK patients with non-ST-segment-elevation myocardial infarction, with or without CKD. Cox regression models were fitted, adjusting for baseline demographics. Compared with patients without CKD, patients with CKD were less frequently prescribed P2Y12 inhibitors (89% versus 86%, P<0.001) less likely to undergo invasive angiography (67% versus 41%, P<0.001) or percutaneous coronary intervention (41% versus 25%, P<0.001), and were less often referred to cardiac rehabilitation (80% versus 66%, P<0.001). Following non-ST-segment-elevation myocardial infarction, patients with CKD had higher risk of 30-day (adjusted hazard ratio [HR], 1.24 [95% CI, 1.20-1.29], 1-year 1.47 [95% CI, 1.44-1.51]) and 5-year mortality 1.55 (95% CI, 1.53-1.58) than patients without CKD (all P<0.001). Risk of mortality over the entire study period was highest in CKD Stage 5 (HR, 2.98 [95% CI, 2.87-3.10]), even after excluding mortality ≤30 days (HR, 3.03 [95% CI, 2.90-3.17]) (P<0.001). There was no significant difference in proportion of deaths attributable to cardiovascular disease at 30 days (CKD; 76% versus no CKD; 76%), or 1 -year (CKD; 62% versus no CKD; 62%).

CONCLUSIONS

Patients with CKD were significantly less likely to receive invasive investigation or undergo percutaneous coronary intervention and had significantly higher risk of short- and longer-term mortality. Risk of mortality increased with reducing CKD stage. Cardiovascular disease was the main cause of mortality in patients with CKD, but at comparable rates to the general population with non-ST-segment-elevation myocardial infarction.

Serum urea increase during hospital stay is associated with worse outcomes after in-hospital cardiac arrest

BACKGROUND

Evaluate the association between serum urea at admission and during hospital stay with return of spontaneous circulation (ROSC) and in-hospital mortality in patients with in-hospital cardiac arrest (IHCA).

METHODS

This retrospective study included patients over 18 years with IHCA attended from May 2018 to December 2022. The exclusion criteria were the absence of exams to calculate delta urea and the express order of "do-not-resuscitate". Data were collected from the electronic medical records. Serum admission urea and urea 24 hours before IHCA were also collected and used to calculate delta urea.

RESULTS

A total of 504 patients were evaluated; 125 patients were excluded due to the absence of variables to calculate delta urea and 5 due to "do-not-resuscitate" order. Thus, we included 374 patients in the analysis. The mean age was 65.0 ± 14.5 years, 48.9% were male, 45.5% had ROSC, and in-hospital mortality was 91.7%. In logistic regression models, ROSC was associated with lower urea levels 24 hours before IHCA (OR: 0.996; CI95%: 0.992-1.000; p: 0.032). In addition, increased levels of urea 24 hours before IHCA (OR: 1.020; CI95%: 1.008-1.033; p: 0.002) and of delta urea (OR: 1.001; CI95%: 1.001-1.019; p: 0.023) were associated with in-hospital mortality. ROC curve analysis showed that the area under the ROC curve for mortality prediction was higher for urea 24 hours before IHCA (Cutoff > 120.1 mg/dL) than for delta urea (Cutoff > 34.83 mg/dL).

CONCLUSIONS

In conclusion, increased serum urea levels during hospital stay were associated with worse prognosis in IHCA.

Comparison of infection and complication rates associated with transvenous vs. subcutaneous defibrillators in patients with stage 4 chronic kidney disease: a multicenter long-term retrospective follow-up

Background

Patients with progressive chronic kidney disease (CKD) are at higher risk of infections and complications from cardiac implantable electronic devices (CIED). In patients with a primary or secondary prophylactic indication, implantable cardiac defibrillators (ICD) can prevent sudden cardiac deaths (SCD). We retrospectively compared transvenous-ICD (TV-ICD) and intermuscularly implanted subcutaneous-ICD (S-ICD) associated infections and complication rates together with hospitalizations in recipients with stage 4 kidney disease.

Methods

We retrospectively analyzed 70 patients from six German centers with stage 4 CKD who received either a prophylactic TV-ICD with a single right ventricular lead, 49 patients, or a S-ICD, 21 patients. Follow-Ups (FU) were performed bi-annually.

Results

The TV-ICD patients were significantly older. This group had more patients with a history of atrial arrhythmias and more were prescribed anti-arrhythmic medication compared with the S-ICD group. There were no significant differences for other baseline characteristics. The median and interquartile range of FU durations were 55.2 (57.6-69.3) months. During FU, patients with a TV-ICD system experienced significantly more device associated infections (n = 8, 16.3% vs. n = 0; p < 0.05), device-associated complications (n = 13, 26.5% vs. n = 1, 4.8%; p < 0.05) and device associated hospitalizations (n = 10, 20.4% vs. n = 1, 4.8%; p < 0.05).

Conclusion

In this long-term FU of patients with stage 4 CKD and an indication for a prophylactic ICD, the S-ICD was associated with significantly fewer device associated infections, complications and hospitalizations compared with TV-ICDs.

Phosphate toxicity and SERCA2a dysfunction in sudden cardiac arrest

Almost half of the people who die from sudden cardiac arrest have no detectable heart disease. Among children and young adults, the cause of approximately one-third of deaths from sudden cardiac arrest remains unexplained after thorough examination. Sudden cardiac arrest and related sudden cardiac death are attributed to dysfunctional cardiac ion-channels. The present perspective paper proposes a pathophysiological mechanism by which phosphate toxicity from cellular accumulation of dysregulated inorganic phosphate interferes with normal calcium handling in the heart, leading to sudden cardiac arrest. During cardiac muscle relaxation following contraction, SERCA2a pumps actively transport calcium ions into the sarcoplasmic reticulum, powered by ATP hydrolysis that produces ADP and inorganic phosphate end products. Reviewed evidence supports the proposal that end-product inhibition of SERCA2a occurs as increasing levels of inorganic phosphate drive up phosphate toxicity and bring cardiac function to a sudden and unexpected halt. The paper concludes that end-product inhibition from ATP hydrolysis is the mediating factor in the association of sudden cardiac arrest with phosphate toxicity. However, current technology lacks the ability to directly measure this pathophysiological mechanism in active myocardium, and further research is needed to confirm phosphate toxicity as a risk factor in individuals with sudden cardiac arrest. Moreover, phosphate toxicity may be reduced through modification of dietary phosphate intake, with potential for employing low-phosphate dietary interventions to reduce the risk of sudden cardiac arrest.

Cause-Specific Mortality in Patients With Advanced Chronic Kidney Disease in the ISCHEMIA-CKD Trial

BACKGROUND

In ISCHEMIA-CKD, 777 patients with advanced chronic kidney disease and chronic coronary disease had similar all-cause mortality with either an initial invasive or conservative strategy (27.2% vs 27.8%, respectively).

OBJECTIVES

This prespecified secondary analysis from ISCHEMIA-CKD (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease) was conducted to determine whether an initial invasive strategy compared with a conservative strategy decreased the incidence of cardiovascular (CV) vs non-CV causes of death.

METHODS

Three-year cumulative incidences were calculated for the adjudicated cause of death. Overall and cause-specific death by treatment strategy were analyzed using Cox models adjusted for baseline covariates. The association between cause of death, risk factors, and treatment strategy were identified.

RESULTS

A total of 192 of the 777 participants died during follow-up, including 94 (12.1%) of a CV cause, 59 (7.6%) of a non-CV cause, and 39 (5.0%) of an undetermined cause. The 3-year cumulative rates of CV death were similar between the invasive and conservative strategies (14.6% vs 12.6%, respectively; HR: 1.13, 95% CI: 0.75-1.70). Non-CV death rates were also similar between the invasive and conservative arms (8.4% and 8.2%, respectively; HR: 1.25; 95% CI: 0.75-2.09). Sudden cardiac death (46.8% of CV deaths) and infection (54.2% of non-CV deaths) were the most common cause-specific deaths and did not vary by treatment strategy.

CONCLUSIONS

In ISCHEMIA-CKD, CV death was more common than non-CV or undetermined death during the 3-year follow-up. The randomized treatment assignment did not affect the cause-specific incidences of death in participants with advanced CKD and moderate or severe myocardial ischemia. (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease [ISCHEMIA-CKD]; NCT01985360).

Hypertension and cardiomyopathy associated with chronic kidney disease: epidemiology, pathogenesis and treatment considerations

Chronic kidney disease (CKD) is a complex condition with a prevalence of 10-15% worldwide. An inverse-graded relationship exists between cardiovascular events and mortality with kidney function which is independent of age, sex, and other risk factors. The proportion of deaths due to heart failure and sudden cardiac death increase with progression of chronic kidney disease with relatively fewer deaths from atheromatous, vasculo-occlusive processes. This phenomenon can largely be explained by the increased prevalence of CKD-associated cardiomyopathy with worsening kidney function. The key features of CKD-associated cardiomyopathy are increased left ventricular mass and left ventricular hypertrophy, diastolic and systolic left ventricular dysfunction, and profound cardiac fibrosis on histology. While these features have predominantly been described in patients with advanced kidney disease on dialysis treatment, patients with only mild to moderate renal impairment already exhibit structural and functional changes consistent with CKD-associated cardiomyopathy. In this review we discuss the key drivers of CKD-associated cardiomyopathy and the key role of hypertension in its pathogenesis. We also evaluate existing, as well as developing therapies in the treatment of CKD-associated cardiomyopathy.

Excess all-cause and cause-specific mortality for people with diabetes and end-stage kidney disease

AIMS

Excess mortality is high in the setting of diabetes and end-stage kidney disease (ESKD), but the effects of ESKD beyond diabetes itself remains incompletely understood. We examined excess mortality in people with diabetes with versus without ESKD, and variation by age, sex and diabetes type.

METHODS

This study included 63,599 people with type 1 (aged 20-69 years; 56% men) and 1,172,160 people with type 2 diabetes (aged 30+ years; 54% men), from the Australian National Diabetes Services Scheme. Initiation of renal replacement therapy and mortality outcomes were obtained via linkage to the Australia and New Zealand Dialysis and Transplant Registry and the National Death Index, respectively. Excess mortality was measured by calculating the mortality rate ratio (MRR) for people with versus without ESKD via indirect standardisation.

RESULTS

A total of 9027 people developed ESKD during 8,601,522 person-years of follow-up. Among people with type 1 diabetes, the MRR was 34.9 (95%CI: 16.6-73.1) in men and 41.5 (20.8-83.1) in women aged 20-29 years and was 5.6 (4.5-7.0) and 7.4 (5.5-10.1) in men and women aged 60-69 years, respectively. In type 2 diabetes, MRRs were 16.6 (8.6-31.8) and 35.8 (17.0-75.2) at age 30-39 years and were 2.8 (2.6-3.1) and 3.6 (3.2-4.1) at age 80+ years in men and women, respectively. Excess cause-specific mortality was highest for peripheral artery disease, cardiac arrest, and infections, and lowest for cancer.

CONCLUSIONS

Among people with diabetes, excess mortality in ESKD is much higher at younger ages and is higher for women compared with men.

Hyperkalemia in Chronic Kidney Disease in the New Era of Kidney Protection Therapies

Despite recent therapeutic advances, chronic kidney disease (CKD) is one of the fastest growing global causes of death. This illustrates limitations of current therapeutic approaches and, potentially, unidentified knowledge gaps. For decades, renin-angiotensin-aldosterone system (RAAS) blockers have been the mainstay of therapy for CKD. However, they favor the development of hyperkalemia, which is already common in CKD patients due to the CKD-associated decrease in urinary potassium (K⁺) excretion and metabolic acidosis. Hyperkalemia may itself be life-threatening as it may trigger potentially lethal arrhythmia, and additionally may limit the prescription of RAAS blockers and lead to low-K⁺ diets associated to low dietary fiber intake. Indeed, hyperkalemia is associated with adverse kidney, cardiovascular, and survival outcomes. Recently, novel kidney protective therapies, ranging from sodium/glucose cotransporter 2 (SGLT2) inhibitors to new mineralocorticoid receptor antagonists have shown efficacy in clinical trials. Herein, we review K⁺ pathophysiology and the clinical impact and management of hyperkalemia considering these developments and the availability of the novel K⁺ binders patiromer and sodium zirconium cyclosilicate, recent results from clinical trials targeting metabolic acidosis (sodium bicarbonate, veverimer), and an increasing understanding of the role of the gut microbiota in health and disease.