Sudden Cardiac Death In Dialysis Patients Research Articles

Sudden Cardiac Death in Dialysis: Arrhythmic Mechanisms and the Value of Non-invasive Electrophysiology.

Sudden Cardiac Death (SCD) is the leading cause of cardiovascular death in dialysis patients. This review discusses potential underlying arrhythmic mechanisms of SCD in the dialysis population. It examines recent evidence from studies using implantable loop recorders and from electrophysiological studies in experimental animal models of chronic kidney disease. The review summarizes advances in the field of non-invasive electrophysiology for risk prediction in dialysis patients focusing on the predictive value of the QRS-T angle and of the assessments of autonomic imbalance by means of heart rate variability analysis. Future research directions in non-invasive electrophysiology are identified to advance the understanding of the arrhythmic mechanisms. A suggestion is made of incorporation of non-invasive electrophysiology procedures into clinical practice.Key Concepts:– Large prospective studies in dialysis patients with continuous ECG monitoring are required to clarify the underlying arrhythmic mechanisms of SCD in dialysis patients.– Obstructive sleep apnoea may be associated with brady-arrhythmias in dialysis patients. Studies are needed to elucidate the burden and impact of sleeping disorders on arrhythmic complications in dialysis patients.– The QRS-T angle has the potential to be used as a descriptor of uremic cardiomyopathy.– The QRS-T angle can be calculated from routine collected surface ECGs. Multicenter collaboration is required to establish best methodological approach and normal values.– Heart Rate Variability provides indirect assessment of cardiac modulation that may be relevant for cardiac risk prediction in dialysis patients. Short-term recordings with autonomic provocations are likely to overcome the limitations of out of hospital 24-h recordings and should be prospectively assessed.

Current Perspectives on Sudden Cardiac Death in Hemodialysis Patients.

Recent lines of evidence suggest that, as in other countries, sudden cardiac death (SCD) is more common in the Japanese dialysis clinical setting than we previously thought. Three specific important findings may underlie the increased incidence of SCD in dialysis patients. Even after successful coronary revascularization, hemodialysis (HD) patients continue to have a higher incidence of SCD than the general population. Second, about 70% or more of end-stage kidney disease patients have concentric and eccentric left ventricular hypertrophy, which predisposes many dialysis patients to interstitial fibrosis, decreased coronary perfusion reserve, and decreased ischemia tolerance. Third, mildly impaired left ventricular dysfunction, with an ejection fraction <50%, is associated with a greater risk of SCD in dialysis patients. We have believed and accepted a common sense theory that paroxysmal ventricular tachycardia and fibrillation are the central cause of SCD in HD patients, because such cardiac functional morphological abnormalities were observed, and there are many chances for ventricular arrhythmia triggers, such as volume expansion and electrolyte shift, to develop. However, the type of fatal arrhythmia responsible for SCD differs between before and after HD. Sudden cardiac arrest (SCA) from ventricular fibrillation (VF) was more often seen in the post-HD setting, while SCA from non-VF, which may be bradyarrhythmia, was more often seen in the pre-HD setting. This may imply that the causes of SCA are bradyarrhythmia due to hyperkalemia in the pre-HD setting on the day after a long interval, and fatal ventricular arrhythmia due to a prolonged QT interval in the post-HD setting, because some recent evidence suggests that shifts of electrolytes, such as potassium and calcium, during HD cause rapid prolongation of the QT interval after HD, which may lead to the onset of ventricular arrhythmia and SCD. In fact, a higher calcium gradient, defined as the difference between the pre-HD corrected total serum calcium level and the dialysate calcium level, was associated with a higher risk of SCD in HD patients. Key Messages: Further study is needed to determine which combination of calcium, potassium, and bicarbonate concentrations in dialysate is optimal to avoid SCD in high-risk HD patients.

Sudden cardiac death in CKD patients.

The risk of sudden cardiac death (SCD) is high in chronic kidney disease patients, and it increases with the progression of kidney function deterioration. The most common causes of SDC are the following: ventricular tachycardia, ventricular tachyarrhythmia, tachycardia torsade de pointes, sustained ventricular fibrillation and bradyarrhythmia. Dialysis influences cardiovascular system and results in hemodynamic disturbances as well as electrolyte shifts altering myocardial electrophysiology. Studies suggest that this procedure exerts both detrimental (poor volume control can exacerbate hypertension and left ventricle hypertrophy) and beneficial effects (associated with fluid removal and subsequent decrease in left ventricle stretch). Dialysis-related vulnerability to serious arrhythmias is the result of sudden shifts in fluid status and electrolytes, particularly potassium, which alter the physiological milieu. Also Ca(2+) ions, in which concentration alters during dialysis, are of key importance in the contraction of vascular smooth muscle cells and cardiac myocytes, thus exerting significant effects on hemodynamics. Due to the fact that SCD occurs with similar frequency in peritoneal dialysis and in hemodialysis patients, it seems that end-stage renal disease factors are more important than the specific ones associated with dialysis type. The results of randomized trials suggested that hemodialysis patients may not derive the same benefit of cardiovascular disease therapy including beta-blockers, calcium channel blockers and angiotensin-converting enzyme inhibitors as the general population with normal kidney function. Noninvasive tests used to stratify SCD risk in HD patients have poor positive value, and thus, combining tests including HRV, baroreceptor sensitivity and effectiveness index as well as its function indices and heart rate turbulence should be implemented. There are only few large randomized placebo-controlled trials assessing the influence of cardioprotective medications or implantable cardioverter defibrillator (ICD) implantation in dialysis patients on life quality and survival, and their results are sometimes contradictory. The decision concerning treatment and/or ICD implantation in this group of patients should be made on the basis of careful assessment of individual risk factors. Moreover, due to the high hazard of cardiovascular mortality including SCD in dialysis patients, physicians should concentrate on the early selection of high-risk patients, monitoring them and introduction of preventive measures.

The association of ECG and echocardiographic abnormalities with sudden cardiac death in a dialysis patient cohort

Cardiovascular mortality is greater in dialysis patients than the general population. More specifically, sudden cardiac death (SCD) accounts for 26% of dialysis patient deaths. However, SCD risk assessment tools used in the general population are not adequate for dialysis patients indicating that the hierarchy of pathopysiological factors appears to be different. The aim of this study was to use simple bedside tests to determine parameters independently predictive of cardiovascular mortality and SCD in dialysis patients. This was a sub-study of the Chronic Renal Insufficient Standards Implementations Study, a longitudinal cohort study of outcomes in CKD. ECG and echocardiographic abnormalities were assessed in a cross-section of prevalent dialysis patients. Patients were followed up until death or transplantation. Forward stepwise Cox regression then determined factors independently associated with all-cause, cardiovascular and SCD mortality. 323 patients were included (age 61.5 ± 14.6years, 113 deaths, 66 cardiovascular deaths, 18 SCD). A number of factors were independently associated with all-cause mortality. These were age, time on dialysis, smoking, the difference between QRS and T-wave axes, resting heart rate, and pulmonary artery pressure (PAP) >35mmHg. The only parameters predictive of SCD were elevated PAP (HR=5.99, p=0.05) and mitral regurgitation (HR=6.71, p=0.01). That PAP is associated with SCD in dialysis patients demonstrates that the pathophysiological mechanism is likely to be different in these patients compared to the general population. Because of this, a population specific approach to risk stratification is advisable.

The Intuitive Case for β‐blockers in Patients with ESRD

Sudden cardiac death (SCD) is common in dialysis patients accounting for up to 25% of all-cause mortality. Unlike in the general population, occlusive coronary artery disease is implicated in a minority of these deaths. Activation of the sympathetic nervous system is prevalent in the dialysis population and may underlie this high rate of SCD. β-blockers reduce SCD in the general population and, given their mode of action, β-blockers would seem to be an ideal class of agents to prevent SCD in dialysis patients. In this review, we will explore the etiology of SCD in dialysis patients and discuss the evidence supporting the use of β-blockers in patients with ESRD. We will also examine potential impediments to the use β-blocker in the dialysis population and outline directions for future trials in this area.

Homoarginine, heart failure, and sudden cardiac death in haemodialysis patients

AimsSudden cardiac death (SCD) is a major contributor to the excess mortality of patients on maintenance dialysis. Homoarginine deficiency may lead to decreased nitric oxide availability and endothelial dysfunction. Based on this rationale we assessed whether homoarginine deficiency is a risk factor for SCD in dialysis patients.Methods and resultsThis study examined the association of homoarginine with cardiovascular outcomes in 1255 diabetic haemodialysis patients from the German diabetes and dialysis study. During a median of 4 years of follow-up, hazard ratios (HR) (95% CI) for reaching the following pre-specified, adjudicated endpoints were determined: SCD, myocardial infarction, stroke, death due to heart failure, and combined cardiovascular events. There was a strong association of low homoarginine concentrations with the presence of congestive heart failure and left ventricular hypertrophy as well as increased levels of brain natriuretic peptide. Per unit decrease in homoarginine, the risk of SCD increased three-fold (HR 3.1, 95% CI 2.0–4.9), attenuating slightly in multivariate models (HR 2.4; 95% CI 1.5–3.9). Patients in the lowest homoarginine quintile experienced a more than two-fold increased risk of SCD, and more than three-fold increased risk of heart failure death than patients in the highest quintile, which accounted for the high incidence of combined cardiovascular events. Low homoarginine showed a trend towards increased risk of stroke, however, myocardial infarction was not meaningfully affected.ConclusionLow homoarginine is a strong risk factor for SCD and death due to heart failure in haemodialysis patients. Further studies are needed to elucidate the underlying mechanisms, offering the potential to develop new interventional strategies.

The current status of interventions aiming at reducing sudden cardiac death in dialysis patients

Mortality in dialysis patients is extremely high, with an annual death rate of approximately 23%. Sudden cardiac death (SCD) is the single largest cause of death in dialysis patients accounting for approximately 60% of all cardiac deaths and 25% of all-cause mortality. Interventions aiming at reducing cardiovascular mortality, especially SCD, in dialysis patients are therefore extremely important and clinically highly relevant. The purpose of this review is to give an outline of the epidemiology of SCD in dialysis patients and to provide a comprehensive overview of several interventional strategies (medical therapies, changing dialysis modality, and revascularization). Furthermore, it will discuss the current knowledge regarding the value of preventive implantable cardioverter defibrillator implantation and address future implications of the interventional strategies mentioned.

Heart rate variability (HRV) in kidney failure: measurement and consequences of reduced HRV

A common cause of death in end-stage renal disease (ESRD) patients on dialysis is sudden cardiac death (SCD). Compared to the general population, the percentage of cardiovascular deaths that are attributed to SCD is higher in patients treated by dialysis. While coronary artery disease (CAD) is the predominant cause of SCD in dialysis patients, reduced heart rate variability (HRV) may play a role in the higher risk of SCD among other risk factors. HRV refers to beat-to-beat alterations in heart rate as measured by periodic variation in the R-R interval. HRV provides a non-invasive method for investigating autonomic input into the heart. It quantifies the amount by which the R-R interval or heart rate changes from one cardiac cycle to the next. The autonomic nervous system transmits impulses from the central nervous system to peripheral organs and is responsible for controlling the heart rate, blood pressure and respiratory activity. In normal individuals, without cardiac disease, the heart rate has a high degree of beat-to-beat variability. HRV fluctuates with respiration: it increases with inspiration and decreases with expiration and is primarily mediated by parasympathetic activity. HRV has been used to evaluate and quantify the cardiac risk associated with a variety of conditions including cardiac disorders, stroke, multiple sclerosis and diabetes. In this narrative review, we will examine the association between HRV and SCD. This report explains the measurement of HRV and the consequences of reduced HRV in the general population and dialysis patients. Lastly, this review will outline the possible use of HRV as a clinical predictor for SCD in the dialysis population. The current understanding of SCD based on HRV findings among the ESRD population support the use of more aggressive treatment of CAD; greater use of angiotensin converting enzyme inhibitor (ACE-i)/angiotensin receptor blockers (ARBs) and beta-blockers and more frequent and/or nocturnal haemodialysis to improve the survival of a patient with kidney failure.