Prevention of sudden cardiac death: rationale and design of the Implantable Cardioverter Defibrillators in Dialysis patients (ICD2) Trial--a prospective pilot study

The incidence and survival after in-hospital cardiopulmonary cerebral resuscitation in end-stage kidney disease patients: A nationwide population-based study

Background

This study analyzed the survival and protective predictors of in-hospital cardiopulmonary cerebral resuscitation (CPCR) to potentially help physicians create effective treatment plans for End-stage kidney disease (ESKD) patients.

Methods

We extracted the data of 7,116 ESKD patients who received their first in-hospital CPCR after initial dialysis between 2004 and 2012 from the National Health Insurance Research Database. The primary outcome was the survival rate during the first in-hospital CPCR. The secondary outcome was the median post-discharge survival.

Results

From 2004 through 2012, the incidence of in-hospital CPCR decreases from 3.97 to 3.67 events per 1,000 admission days (P for linear trend <0.001). The survival rate for the first in-hospital CPCR did not change significantly across the 9 years (P for trend = 0.244), whereas the median survival of post-discharge survival increased significantly from 3.0 months in 2004 to 6.8 months in 2011 (P for linear trend <0.001). In addition, multivariable analysis identified older age as a risk factor and prior intracardiac defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) implantation as a protective factor for in-hospital death during the first in-hospital CPCR.

Conclusion

The incidence of in-hospital CPCR and the duration post-discharge among ESKD patients improved despite there being no significant difference in the survival rate of ESKD patients after CPCP. Either ICD or CRT-D implantation may be advisable for ESKD patients with a high risk of sudden cardiac death.

Cardiovascular complications in chronic dialysis patients

PURPOSE OF REVIEW

This review article focuses on the most significant cardiovascular complications in dialysis patients [sudden cardiac death (SCD), acute coronary syndromes, heart failure, and atrial fibrillation].

RECENT FINDINGS

Current and ongoing research aims to quantify the rate and pattern of significant arrhythmia in dialysis patients and to determine the predominant mechanism of SCD. Preliminary findings from these studies suggest a high rate of atrial fibrillation and that bradycardia and asystole may be more frequent than ventricular arrhythmia as a cause of sudden death. A recently published matched cohort study in dialysis patients who received a defibrillator for primary prevention showed that there was no significant difference in mortality rates between defibrillator-treated patients and propensity-matched controls. Two randomized controlled trials are currently recruiting participants and will hopefully answer the question of whether implantable or wearable cardioverter defibrillators can prevent SCD. An observational study using United States Renal Data System data demonstrated how difficult it is to keep hemodialysis patients on warfarin, as more than two-thirds discontinued the drug during the first year. The ISCHEMIA-CKD trial may provide answers about the optimal strategy for the treatment of atherosclerotic coronary disease in patients with advanced chronic kidney disease.

SUMMARY

The article reviews the diagnosis of acute coronary syndromes in dialysis patients, current literature on myocardial revascularization, and data on fatal and nonfatal cardiac arrhythmia. The new classification of heart failure in end-stage renal disease is reviewed. Finally, available cohort studies on warfarin for stroke prevention in dialysis patients with atrial fibrillation are reviewed.

Echocardiographic associates of atrial fibrillation in end-stage renal disease

Background

The prevalence of atrial fibrillation (AF) in end-stage renal disease (ESRD) patients is relatively high. The present study evaluated the association between left atrial (LA) remodelling, including an increased size and myocardial fibrosis, and slow LA conduction and the occurrence of AF.

Methods

In 171 ESRD patients enrolled in the Implantable Cardioverter Defibrillators in Dialysis patients (ICD2) trial, the LA dimensions, LA conduction delay [as reflected by the time difference between P-wave onset on surface electrocardiogram and A'-wave on tissue Doppler imaging (PA-TDI)] and LA function were compared between patients who exhibited AF versus patients without AF. Based on ICD remote monitoring or clinical records, the occurrence of AF was detected.

Results

Of 171 patients, 47 (27%) patients experienced AF. Despite comparable left ventricular ejection fraction and prevalence of significant mitral regurgitation, patients with AF had significantly larger LA volume index (mean ± standard deviation) (29 ± 11 versus 23 ± 10 mL/m2, P = 0.001), longer PA-TDI duration (144 ± 30 versus 131 ± 27 ms, P = 0.010) and reduced late diastolic mitral annular velocity (A') (7.1 ± 2.8 versus 8.2 ± 2.4 cm/s, P = 0.012) compared with patients without AF. On multivariable analysis, larger LA volume index [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.01-1.08, P = 0.017], longer PA-TDI duration (OR 1.02, 95% CI 1.00-1.03, P = 0.025) and reduced A' (OR 0.84, 95% CI 0.72-0.98, P = 0.025) were independently associated with AF after adjusting for age and left ventricle diastolic relaxation.

Conclusion

ESRD patients with AF show more advanced changes in the LA substrate than ESRD patients without AF.

Do Implantable Cardioverter Defibrillators Reduce Mortality in Patients With Chronic Kidney Disease at All Stages?

The benefits of implantable cardioverter defibrillator (ICD) implantation in chronic kidney disease (CKD) patients with high sudden cardiac death (SCD) risk are uncertain. To clarify the effects of receiving an ICD in CKD patients, we conducted this meta-analysis to identify the effects of ICDs on patients with CKD, including those on dialysis. We searched the Cochrane library, EMBASE, PubMed, and clinical trials for studies published before July 2016. Eleven studies including 20,196 CKD patients were considered for inclusion. The pooled analysis suggested that patients with an estimated glomerular filtration rate (eGFR) < 60 mL/minute/1.73 m2 would benefit from receiving treatments with ICDs compared with patients without an ICD device (aHR = 0.74; 95% confidence interval [CI], 0.63 to 0.86). [corrected]. This is the first report of a subgroup analysis on the survival rate of ICD implantation in CKD patients according to an eGFR group. The subgroup analysis indicated a similar protective association of ICDs in stage 3 (aHR = 0.71; 95% CI, 0.61 to 0.82) and 5 (aHR = 0.71; 95% CI, 0.54 to 0.92) CKD patients [corrected] compared with the control group. However, there was no significant improvement in all-cause mortality in stage 4 CKD patients (aHR = 1.02; 95%CI, 0.75 to 1.37) [corrected]. This is the first meta-analysis reporting that ICD implantation reduces all-cause mortality in stage 3 and 5 [corrected] CKD patients. However, the data do not indicate there is any benefit to ICD implantation in stage 4 [corrected] CKD patients.

Abdominal aortic calcification on a plain X-ray and the relation with significant coronary artery disease in asymptomatic chronic dialysis patients

Background

Coronary artery disease (CAD) is common in asymptomatic chronic dialysis patients and plays an important role in their poor survival. Early identification of these high-risk patients could improve treatment and reduce mortality. Abdominal aortic calcification (AAC) has previously been associated with CAD in autopsy studies. Since the AAC can be quantified easily using a lateral lumbar X-ray we hypothesized that the extent of AAC as assessed on a lateral lumbar X-ray might be predictive of the presence of significant CAD in dialysis patients.

Methods

All patients currently enrolled in the ICD2 trial without a history of CABG or a PCI with stent implantation were included in this study. All patients underwent CT-angiography (CTA) and a lateral X-ray of the abdomen. AAC on X-ray was quantified using a previously validated scoring system whereupon the association between AAC and the presence of significant CAD was assessed.

Results

A total of 90 patients were included in this study (71% male, 67 ± 7 years old). Forty-six patients were found to have significant CAD. AAC-score was significantly higher in patients with CAD (10.1 ± 4.9 vs 6.3 ± 4.6 (p < 0.05). Multivariate regression analysis revealed that AAC score is an independent predictor for the presence of CAD with a 1,2 fold higher risk per point increase (p < 0.01). The AAC score has a sensitivity of 85% and a specificity of 57% for the presence of significant CAD.

Conclusion

This study shows that abdominal aortic calcification as assessed on a lateral lumbar X-ray is predictive for the presence of significant coronary artery disease in asymptomatic dialysis patients. This simple, non-invasive and cheap screening method could contribute to early identification of patients eligible for further screening of CAD.

Trial registration

NTR948, registered 10-4-2007 ; ISRCTN20479861, registered 2-5-2007

Electrocardiographic predictors of mortality and sudden cardiac death in patients with end stage renal disease on hemodialysis

Patients with end stage renal disease (ESRD) on hemodialysis experience a high incidence of cardiovascular mortality, and sudden cardiac death (SCD) accounts for approximately 25% of all deaths in this patient population. Despite this high risk of SCD, many non-invasive SCD risk stratification tools that are frequently applied to other patient populations (such as those with prior myocardial infarction and reduced left ventricular systolic function) may be less useful markers of increased SCD risk in ESRD. Improved SCD risk stratification tools for use specifically in patients on hemodialysis are therefore necessary to optimally target use of primary prevention interventions aimed at decreasing SCD incidence. Electrocardiography is an effective, non-invasive SCD risk stratification tool in hemodialysis patients. This article reviews data supporting the association between various ECG parameters (QT interval, spatial QRS-T angle, signal averaged ECG, heart rate variability, and T-wave alternans) and mortality/SCD in the dialysis population. Despite the association between abnormal ECG parameters and SCD, it remains unclear if these abnormal parameters (such as prolonged QT interval) are mechanistically related to SCD and/or ventricular arrhythmias, or if they are simply markers for more severe cardiac disease, such as left ventricular hypertrophy, that may independently predispose to SCD. Current obstacles that impair widespread implementation of ECG risk stratification in the hemodialysis population are also discussed.

Sudden cardiac death and chronic kidney disease: From pathophysiology to treatment strategies

Chronic kidney disease (CKD) patients demonstrate higher rates of cardiovascular mortality and morbidity; and increased incidence of sudden cardiac death (SCD) with declining kidney failure. Coronary artery disease (CAD) associated risk factors are the major determinants of SCD in the general population. However, current evidence suggests that in CKD patients, traditional cardiovascular risk factors may play a lesser role. Complex relationships between CKD-specific risk factors, structural heart disease, and ventricular arrhythmias (VA) contribute to the high risk of SCD. In dialysis patients, the occurrence of VA and SCD could be exacerbated by electrolyte shifts, divalent ion abnormalities, sympathetic overactivity, inflammation and iron toxicity. As outcomes in CKD patients after cardiac arrest are poor, primary and secondary prevention of SCD and cardiac arrest could reduce cardiovascular mortality in patients with CKD.

Serum Cardiac Troponin-I is Superior to Troponin-T as a Marker for Left Ventricular Dysfunction in Clinically Stable Patients with End-Stage Renal Disease

Background

Serum troponin assays, widely used to detect acute cardiac ischemia, might be useful biomarkers to detect chronic cardiovascular disease (CVD). Cardiac-specific troponin-I (cTnI) and troponin-T (cTnT) generally detect myocardial necrosis equally well. In dialysis patients however, serum cTnT levels are often elevated, unlike cTnI levels. The present study aims to elucidate the associations of cTnI and cTnT with CVD in clinically stable dialysis patients.

Methods

Troponin levels were measured using 5^th generation hs-cTnT assays (Roche) and STAT hs-cTnI assays (Abbott) in a cohort of dialysis patients. Serum troponin levels were divided into tertiles with the lowest tertile as a reference value. Serum troponins were associated with indicators of CVD such as left ventricular mass index (LVMI), left ventricular ejection fraction (LVEF) and the presence of coronary artery disease (CAD). Associations were explored using regression analysis.

Results

We included 154 consecutive patients, 68±7 years old, 77% male, 70% hemodialysis. Median serum cTnT was 51ng/L (exceeding the 99^th percentile of the healthy population in 98%) and median serum cTnI was 13ng/L (elevated in 20%). A high cTnI (T3) was significantly associated with a higher LVMI (Beta 31.60; p=0.001) and LVEF (Beta -4.78; p=0.005) after adjusting for confounders whereas a high serum cTnT was not. CAD was significantly associated with a high cTnT (OR 4.70 p=0.02) but not with a high cTnI. Unlike cTnI, cTnT was associated with residual renal function (Beta:-0.09; p=0.006).

Conclusion

In the present cohort, serum cTnI levels showed a stronger association with LVMI and LVEF than cTnT. However, cTnT was significantly associated with CAD and residual renal function, unlike cTnI. Therefore, cTnI seems to be superior to cTnT as a marker of left ventricular dysfunction in asymptomatic dialysis patients, while cTnT might be better suited to detect CAD in these patients.

Cardiac imaging in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) carry a high cardiovascular risk. In this patient group, cardiac structure and function are frequently abnormal and 74% of patients with CKD stage 5 have left ventricular hypertrophy (LVH) at the initiation of renal replacement therapy. Cardiac changes, such as LVH and impaired left ventricular systolic function, have been associated with an unfavourable prognosis. Despite the prevalence of underlying cardiac abnormalities, symptoms may not manifest in many patients. Fortunately, a range of available and emerging cardiac imaging tools may assist with diagnosing and stratifying the risk and severity of heart disease in patients with CKD. Moreover, many of these techniques provide a better understanding of the pathophysiology of cardiac abnormalities in patients with renal disease. Knowledge of the currently available cardiac imaging modalities might help nephrologists to choose the most appropriate investigative tool based on individual patient circumstances. This Review describes established and emerging cardiac imaging modalities in this context, and compares their use in CKD patients with their use in the general population.

Influence of hemodialysis duration on mid-term clinical outcomes in hemodialysis patients with coronary artery disease after drug-eluting stent implantation

Accelerated atherosclerosis in prolonged maintenance hemodialysis (HD) has been recognized; however, whether HD duration is associated with poor clinical outcome in HD patients with coronary artery disease (CAD) after drug-eluting stent (DES) implantation is unknown. We evaluated the impact of HD duration on clinical outcomes in HD patients with CAD after DES implantation. Between April 2007 and December 2012, 168 angina pectoris patients (320 de novo lesions) on HD were treated with DES. Major adverse cardiovascular events (MACE) and target lesion revascularization (TLR) were investigated at 3 years according to the HD duration (≤ 3 years, 83 patients; >3 years, 85 patients). The incidence of MACE was significantly higher in the long HD duration group (25.3 vs. 50.6 %; P = 0.001). Especially, sudden cardiac death (SCD) was significantly higher in the long HD duration group (3.6 vs. 16.5 %; P = 0.006). On the other hand, the rates of TLR were similar between the two groups (12.0 vs. 14.1 %; P = 0.69). Cox's proportional hazard analysis revealed that HD duration (HR 1.08 per year, 95 % CI 1.03-1.13, P = 0.002), β-blocker use (0.28, 0.17-0.46, P < 0.001), and diabetes mellitus (2.10, 1.23-3.56, P = 0.007) were independent predictors of MACE. Longer HD duration did not affect TLR; however, SCD was significantly higher in the long HD duration group.

Soluble Klotho is not independently associated with cardiovascular disease in a population of dialysis patients

Background

Dialysis patients suffer from a high burden of cardiovascular disease (CVD). Partly this is due to progressive deterioration of calcium-phosphate homeostasis. Previous studies suggested that besides FGF-23, low levels of Klotho, a protein linked to aging, might constitute a key factor in this detrimental relationship. The purpose of the present study was to determine the relationship between serum Klotho (sKlotho) and the presence of CVD in dialysis patients.

Methods

Plasma levels of sKlotho were measured in a cohort of dialysis patients and related to left ventricular (LV) dysfunction (defined as a LV ejection fraction <45%) and LV mass using echocardiography. Coronary artery disease (CAD) and calcification score were assessed using computed tomography angiography. Abdominal aortic calcification score (AACscore) was measured by abdominal X-ray.

Results

We included 127 dialysis patients, 67 ± 7 years old, 76% male, 67% on hemodialysis, median sKlotho 460 pg/mL (25th-75th percentile 350-620 pg/mL). Patients with a low sKlotho (<460 pg/mL) showed significantly more CAD (81% versus 61%; p = 0.02) and LV dysfunction (19% versus 3%; p < 0.01). However, after adjusting for confounders, sKlotho was not independently associated with the presence of CVD or the AACscore.

Conclusions

In the present cohort of dialysis patients, sKlotho was not independently associated with CVD. However, patients with a low sKlotho level (<460 pg/mL) did show CAD and LV dysfunction more frequently. Therefore, while sKlotho might be a marker for CVD in dialysis patients, the current data does not support a direct cardioprotective effect of sKlotho.

Primary prevention implantable cardioverter defibrillators in end-stage kidney disease patients on dialysis: a matched cohort study

BACKGROUND

Sudden cardiac death is the leading cause of death among end-stage kidney disease patients (ESKD) on dialysis, but the benefit of primary prevention implantable cardioverter defibrillators (ICDs) in this population is uncertain. We conducted this investigation to compare the mortality of dialysis patients receiving a primary prevention ICD with matched controls.

METHODS

We used data from the National Cardiovascular Data Registry's ICD Registry to select dialysis patients who received a primary prevention ICD, and the Get with the Guidelines-Heart Failure Registry to select a comparator cohort. We matched ICD recipients and no-ICD patients using propensity score techniques to reduce confounding, and overall survival was compared between groups.

RESULTS

We identified 108 dialysis patients receiving primary prevention ICDs and 195 comparable dialysis patients without ICDs. One year (3-year) mortality was 42.2% (68.8%) in the ICD registry cohort compared with 38.1% (75.7%) in the control cohort. There was no significant survival advantage associated with ICD [hazard ratio (HR) 0.87, 95% confidence interval (CI) 0.66-1.13, log-rank P = 0.29]. After propensity matching, our analysis included 86 ICD patients and 86 matched controls. Comparing the propensity-matched cohorts, 1 year (3 years) mortality was 43.4% (74.0%) in the ICD cohort and 39.7% (76.6%) in the control cohort; there was no significant difference in mortality outcome between groups (HR = 0.94, 95% CI: 0.67-1.31, log-rank P = 0.71).

CONCLUSIONS

We did not observe a significant association between primary prevention ICDs and reduced mortality among ESKD patients receiving dialysis. Consideration of the potential risks and benefits of ICD implantation in these patients should be undertaken while awaiting the results of definitive clinical trials.

Sudden cardiac death in end stage renal disease: unlocking the mystery

Sudden cardiac death (SCD) is a major cause of concern in end stage renal disease (ESRD), contributing to 70% of cardiovascular mortality and 27% of all-cause mortality in dialysis patients. Yet its mechanisms and pathogenesis remain largely obscure. This review discusses the potential reasons for an exaggerated risk of SCD in ESRD populations taking into account recent studies and registry data and additionally explores the reasons for the reported recent decline in SCD. The types of arrhythmias typical of the hemodialysis population are yet to be fully characterised and in this paper, we introduce an ongoing implantable loop recorder (ILR) based study in hemodialysis patients--CRASH ILR (Cardio Renal Arrhythmia Study in Haemodialysis patients using Implantable Loop Recorders). The findings of this study will hopefully guide the design and implementation of larger ILR based studies before undertaking larger scale interventional therapeutic trials in this high risk population.

A meta-analysis of mortality in end-stage renal disease patients receiving implantable cardioverter defibrillators (ICDs)

Data on the effectiveness of implantable implantable cardioverter defibrillators (ICDs) with respect to reducing mortality in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) are lacking. The purpose of this meta-analysis was to compare the mortality of patients with ESRD who have received and not received an ICD. A search was conducted on January 31, 2013 of Medline, Cochrane, EMBASE, and Google Scholar. Studies were selected for inclusion based on the following criteria. 1) Randomized controlled trial. 2) ESRD patients with heart failure. 3) Device therapy (ICD, CRT-defibrillator [CRT-D]) used to treat heart failure. 4) Primary outcome is survival analysis. 5) Retrospective study if survival analysis was performed. The primary outcome was overall survival (OS), and the secondary outcome was 2-year survival. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated, and a χ2-based test of homogeneity was performed. Three studies were included in the analysis. The combined OR for OS was 2.245 (95% CI 1.871 to 2.685, P<0.001), indicating that patients with an ICD had a significantly higher OS than those without an ICD. The combined OR for 2-year survival was 2.312 (95% CI 1.921 to 2.784, P<0.001), indicating that patients with an ICD had a significantly higher 2-year survival rate than those without an ICD. The use of ICD in patients with ESRD is associated with an increase in the OS and the 2-year survival rate.

Potassium balance in dialysis patients

The advent of dialytic therapy has enabled nephrologists to provide life-saving therapy, but potassium balance continues to be an ever present challenge in the ESRD population. Although a small percent of patients are chronically hypokalemic, hyperkalemia is by far the most common abnormality in dialysis patients. It is associated with increased all-cause mortality, cardiovascular mortality, and arrhythmogenic death. Although alterations of the dialysis bath may decrease predialysis potassium, potassium baths <2 mEq/l are associated with a higher risk of sudden cardiac death. Studies show that patients are aware of the risks of hyperkalemia, but adherence to a low potassium diet is suboptimal. ACEI, ARBs, and spironolactone may cause slight increases in potassium even in anuric patients, requiring increased surveillance. Fludrocortisone and potassium binders have not been proven to be beneficial in lowering interdialytic potassium levels. Frequent hemodialysis may be a viable option, and studies of prophylactic placement of implantable cardioverter/defibrillators are underway.

Implantable cardioverter-defibrillators for primary prevention of sudden cardiac death in CKD: a meta-analysis of patient-level data from 3 randomized trials

BACKGROUND

The benefit of a primary prevention implantable cardioverter-defibrillator (ICD) among patients with chronic kidney disease is uncertain.

STUDY DESIGN

Meta-analysis of patient-level data from randomized controlled trials.

SETTING & POPULATION

Patients with symptomatic heart failure and left ventricular ejection fraction<35%.

SELECTION CRITERIA FOR STUDIES

From 7 available randomized controlled studies with patient-level data, we selected studies with available data for important covariates. Studies without patient-level data for baseline estimated glomerular filtration rate (eGFR) were excluded.

INTERVENTION

Primary prevention ICD versus usual care effect modification by eGFR.

OUTCOMES

Mortality, rehospitalizations, and effect modification by eGFR.

RESULTS

We included data from the Multicenter Automatic Defibrillator Implantation Trial I (MADIT-I), MADIT-II, and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). 2,867 patients were included; 36.3% had eGFR<60 mL/min/1.73m2. Kaplan-Meier estimate of the probability of death during follow-up was 43.3% for 1,334 patients receiving usual care and 35.8% for 1,533 ICD recipients. After adjustment for baseline differences, there was evidence that the survival benefit of ICDs in comparison to usual care depends on eGFR (posterior probability for null interaction P<0.001). The ICD was associated with survival benefit for patients with eGFR≥60 mL/min/1.73 m2 (adjusted HR, 0.49; 95% posterior credible interval, 0.24-0.95), but not for patients with eGFR<60 mL/min/1.73 m2 (adjusted HR, 0.80; 95% posterior credible interval, 0.40-1.53). eGFR did not modify the association between the ICD and rehospitalizations.

LIMITATIONS

Few patients with eGFR<30 mL/min/1.73 m2 were available. Differences in trial-to-trial measurement techniques may lead to residual confounding.

CONCLUSIONS

Reductions in baseline eGFR decrease the survival benefit associated with the ICD. These findings should be confirmed by additional studies specifically targeting patients with varying eGFRs.

Echocardiographical determinants of an abnormal spatial QRS-T angle in chronic dialysis patients

BACKGROUND

The spatial QRS-T angle describes the relation between ventricular depolarization and repolarization. Having a wide (abnormal) angle is considered an important predictor of arrhythmic events. Given the high incidence of sudden cardiac death in dialysis patients, this parameter is of particular interest in this patient group. The objective of this study was to assess the association of (modifiable) echocardiographic parameters and an abnormal spatial QRS-T angle in dialysis patients.

METHODS

A total of 94 consecutive dialysis patients were included. In all patients a 12-lead electrocardiogram (ECG), a two-dimensional echocardiogram and routine blood samples were obtained. The spatial QRS-T angle was then calculated from the 12-lead ECG. An abnormal spatial QRS-T angle was defined as ≥130° in males and ≥116° in females.

RESULTS

An abnormal spatial QRS-T angle was present in 27 (29%) patients. Patients with an abnormal spatial angle had a lower left ventricular ejection fraction (LVEF) of 47 ± 7 versus 55 ± 6% (P < 0.001) and had a higher left ventricular (LV) dyssynchrony, with a septal to lateral (S-L) delay of peak systolic velocity of 70 inter quartile range (iIQR) (40, 100) ms versus 30 IQR (10, 70) ms (P = 0.001), respectively. Multivariate logistic regression analysis controlling for possible confounders demonstrated that LVEF [odds ratio (OR) 0.82; 95% confidence interval (CI) 0.72-0.93, P = 0.001] and LV dyssynchrony (OR 1.19 per 10 ms; 95% CI 1.03-1.38, P = 0.02) were independent determinants of an abnormal spatial QRS-T angle in this patient group.

CONCLUSIONS

LVEF and dyssynchrony are echocardiographic determinants of an abnormal spatial QRS-T angle in dialysis patients and might therefore represent a potential target for the prevention of sudden cardiac death in these patients.

CT coronary angiography is feasible for the assessment of coronary artery disease in chronic dialysis patients, despite high average calcium scores

Purpose

Significant obstructive coronary artery disease (CAD) is common in asymptomatic dialysis patients. Identifying these high risk patients is warranted and may improve the prognosis of this vulnerable patient group. Routine catheterization of incident dialysis patients has been proposed, but is considered too invasive. CT-angiography may therefore be more appropriate. However, extensive coronary calcification, often present in this patient group, might hamper adequate lumen evaluation. The objective of this study was to assess the feasibility of CT-angiography in this patient group.

Methods

For this analysis all patients currently participating in the ICD2 trial (ISRCTN20479861), with no history of PCI or CABG were included. The major epicardial vessels were evaluated on a segment basis (segment 1–3, 5–8, 11 and 13) by a team consisting of an interventional and an imaging specialist. Segments were scored as not significant, significant and not interpretable.

Results

A total of 70 dialysis patients, with a mean age of 66±8 yrs and predominantly male (70%) were included. The median calcium score was 623 [79, 1619].

Over 90% of the analyzed segments were considered interpretable. The incidence of significant CAD on CT was 43% and was associated with cardiovascular events during follow-up. The incidence of cardiovascular events after 2-years follow-up: 36% vs. 0% in patients with no significant CAD (p<0.01).

Conclusion

Despite the high calcium scores CT-angiography is feasible for the evaluation of the extent of CAD in dialysis patients. Moreover the presence of significant CAD on CT was associated with events during follow-up.

Left ventricular diastolic dysfunction in dialysis patients assessed by novel speckle tracking strain rate analysis: prevalence and determinants

Background. Diastolic dysfunction is common among dialysis patients and is associated with increased morbidity and mortality. Novel echocardiographic speckle tracking strain analysis permits accurate assessment of left ventricular diastolic function, independent of loading conditions and taking all myocardial segments into account. The aim of the study was to evaluate the prevalence of diastolic dysfunction in chronic dialysis patients using this novel technique, and to identify its determinants among clinical and echocardiographic variables. Methods. Patients currently enrolled in the ICD2 study protocol were included for this analysis. Next to conventional echo measurements diastolic function was also assessed by global diastolic strain rate during isovolumic relaxation (SRIVR). Results. A total of 77 patients were included (age 67 ± 8 years, 74% male). When defined as E/SRIVR ≥236, the prevalence of diastolic dysfunction was higher compared to more conventional measurements (48% versus 39%). Left ventricular mass (OR 1.02, 95% CI 1.00–1.04, P = 0.014) and pulse wave velocity (OR 1.34, 95% CI 1.07–1.68, P = 0.01) were independent determinants of diastolic dysfunction. Conclusion. Diastolic dysfunction is highly prevalent among dialysis patients and might be underestimated using conventional measurements. Left ventricular mass and pulse wave velocity were the only determinants of diastolic dysfunction in these patients.

Sudden cardiac death in dialysis: do current guidelines for implantable cardioverter defibrillator therapy apply to patients with end-stage kidney disease?

Arrhythmic mechanisms account for one in four deaths in end-stage kidney disease. Large-scale randomized controlled trials have demonstrated a mortality benefit from implantable cardioverter defibrillator therapy in carefully selected patient groups at high risk for sudden cardiac death. Unfortunately, patients with end-stage kidney disease were systematically excluded from these trials. Consequently, the applicability of American College of Cardiology (ACC)/American Heart Association (AHA)/Heart Rhythm Society (HRS) guidelines on implantable cardioverter defibrillator therapy to dialysis patients remains uncertain. Observational data suggest that secondary preventative implantable cardioverter defibrillator therapy following resuscitated cardiac arrest prolongs the lives of dialysis patients. This intervention may also offer a survival advantage as a primary preventative strategy in end-stage kidney disease. However, competing risk from co-morbidity can negate any perceived benefit. Device-related complications also negatively impact outcome. The recommendation that primary preventative device implantation be reserved for patients with severely impaired left ventricular function may be excessively restrictive in this high-risk population. Trials of implantable cardioverter defibrillator therapy that include dialysis patients are required to validate existing device eligibility criteria in this unique population. Novel indications for this intervention in dialysis patients should also be identified.

Wasting and sudden cardiac death in hemodialysis patients: a post hoc analysis of 4D (Die Deutsche Diabetes Dialyse Studie)

BACKGROUND

Wasting is common in hemodialysis patients and often is accompanied by cardiovascular disease and inflammation. The cardiovascular risk profile meaningfully changes with the progression of kidney disease, and little is known about the impact of wasting on specific clinical outcomes. This study examined the effects of wasting on the various components of cardiovascular outcome and deaths caused by infection in hemodialysis patients.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

1,255 hemodialysis patients from 178 centers participating in Die Deutsche Diabetes Dialyse Studie (4D) in 1998-2004.

PREDICTOR

Moderate wasting was defined as body mass index, albumin, and creatinine values less than the median (26.7 kg/m(2), 3.8 g/dL, and 6.8 mg/dL, respectively) and C-reactive protein level less than the median (5 mg/L) at baseline. Severe wasting was defined as body mass index, albumin, and creatinine levels less than the median and C-reactive protein level greater than the median at baseline.

OUTCOMES & MEASUREMENTS

Risks of sudden cardiac death (SCD), myocardial infarction (MI), stroke, combined cardiovascular events, deaths due to infection, and all-cause mortality were determined using Cox regression analyses during a median of 4 years of follow-up.

RESULTS

196 patients had wasting (severe, n = 109; and moderate, n = 87). Overall, 617 patients died (160 of SCD and 128 of infectious deaths). Furthermore, 469 patients experienced a cardiovascular event, with MI and stroke occurring in 200 and 103 patients, respectively. Compared with patients without wasting (n = 1,059), patients with severe wasting had significantly increased risks of SCD (adjusted HR, 1.8; 95% CI, 1.1-3.1), all-cause mortality (adjusted HR, 1.8; 95% CI, 1.4-2.4), and deaths due to infection (adjusted HR, 2.3; 95% CI, 1.2-4.3). In contrast, MI was not affected. The increased risk of cardiovascular events (adjusted HR, 1.5; 95% CI, 1.0-2.1) was explained mainly by the effect of wasting on SCD.

LIMITATIONS

Selective patient cohort.

CONCLUSIONS

Wasting was associated strongly with SCD, but not MI, in diabetic hemodialysis patients. Nonatherosclerotic cardiac disease potentially has a major role to account for the increased cardiovascular events in patients with wasting, suggesting the need for novel treatment strategies.

Sudden cardiac death in patients with chronic kidney disease: prevention is the sine qua non

Despite developments in the technology of dialysis procedures and improvements in the understanding of systemic derangements related to chronic kidney disease (CKD), cardiovascular disease is the major cause of death. Unfortunately, the leading subset of cardiovascular disease death is sudden cardiac death (SCD). To date much effort has been exerted to figure out the clues pointing to the risk of future development of SCD in patients with CKD. However, none of these factors satisfactorily detects a truly vulnerable dialysis patient. Thus, recently, it has been advocated that a combination of noninvasive risk assessment methods, carefully chosen to reflect the different aspects of the underlying pathology and changes in the myocardial substrate in CKD, could help to identify patients at high risk of SCD within the CKD. In this review, we aimed to summarize what is known about risk stratification of patients with CKD and appropriate prevention strategies with a special emphasis on recent developments and the use of complimentary tests perhaps as a risk prediction rule.

Prevention of sudden cardiac arrest in dialysis patients: can we do more to improve outcomes?

Sudden cardiac arrest (SCA) is a leading cause of cardiac-associated mortality in dialysis patients. Risk factors unique to hemodialysis patients include abnormal electrolytes, large-volume ultrafiltration, and prior history of cardiac disease. Few randomized controlled trials of standard cardiac interventions have been completed in dialysis patients. Observational studies suggest that modification of the dialysis prescription may be one place to intervene. Prospective research is needed to determine mechanisms of SCA in hemodialysis patients.

Sudden cardiac death in hemodialysis patients: an in-depth review

Sudden cardiac death (SCD) is the leading cause of death in hemodialysis patients, accounting for death in up to one-quarter of this population. Unlike in the general population, coronary artery disease and heart failure often are not the underlying pathologic processes for SCD; accordingly, current risk stratification tools are inadequate when assessing these patients. Factors assuming greater importance in hemodialysis patients may include left ventricular hypertrophy, electrolyte shift, and vascular calcification. Knowledge regarding SCD in hemodialysis patients is insufficient, in part reflecting the lack of an agreed-on definition of SCD in this population, although epidemiologic studies suggest the most common times for SCD to occur are toward the end of the long 72-hour weekend interval between dialysis sessions and in the 12 hours immediately after hemodialysis. Accordingly, it is hypothesized that the dialysis procedure itself may have important implications for SCD. Supporting this is recognition that hemodialysis is associated with both ventricular arrhythmias and dynamic electrocardiographic changes. Importantly, echocardiography and electrocardiography may show changes that are modifiable by alterations to dialysis prescription. The most effective preventative strategy in the general population, implanted cardioverter-defibrillator devices, are less effective in the presence of chronic kidney disease and have not been studied adequately in dialysis patients. Last, many dialysis patients experience SCD despite not fulfilling current criteria for implantation, making appropriate allocation of defibrillators uncertain.

Effect of renal function on survival after implantable cardioverter defibrillator placement

Implantable cardioverter defibrillators (ICDs) are effective at reducing arrhythmic death in patients with left ventricular dysfunction, but few studies have investigated the outcomes after ICD implantation in patients with chronic kidney disease (CKD). We conducted a 2-center retrospective study of 958 patients who had undergone ICD placement for primary prevention from the 2000 to 2006. The patients were stratified into 5 groups according to the CKD stage (stage 1, glomerular filtration [GFR] 90 to 120 ml/min; stage 2, GFR 60 to 89 ml/min; stage 3, GFR 30 to 59 ml/min; stage 4, GFR 15 to 29 ml/min; and stage 5, GFR 0 to 14 ml/min). The primary end point was death at 1 year. Of the 958 patients included in our analysis, 73 (7.6%) had died at 1 year. The mortality rate at 1 year increased with worsening CKD (1.8%, 5.3%, 9.0%, 22%, and 38% for stage 1 to 5, respectively, p <0.0001 for group). CKD was an independent predictor of mortality; hazard ratio 1.0, 1.075 (95% confidence interval 0.578 to 2.0), 1.372 (95% confidence interval 0.736 to 2.556), 3.092 (95% confidence interval 1.52 to 6.29), and 10.15 (95% confidence interval 4.25 to 24.23) for stage 1 to 5, respectively (p <0.0001 for group). Patients with CKD and left ventricular dysfunction have a poor prognosis despite ICD placement. The 1-year mortality increased as the renal function decreased. In conclusion, physicians should be cognizant of the prognosis when considering whether an ICD should be implanted in patients with CKD.

End-Stage Renal Disease and Sudden Cardiac Death

Patients with end-stage renal disease (ESRD) are at a high risk for sudden cardiac death (SCD). SCD is the most common cause of death in this population and, as in the general population, ventricular arrhythmias seem to be the most common cause of SCD. The increased risk of SCD in ESRD is likely due to factors that are unique to the metabolic derangements associated with this state, as well as the increased prevalence of traditional risk factors. Despite this, the evidence base for the assessment and management of SCD in these patients is limited. This article reviews the current data on underlying risk factors for SCD in patients with ESRD, the role of common medical and device-based therapies for the prevention and treatment of SCD, and the applicability of common methods of risk stratification to patients with ESRD.

Meta-analysis of mortality in dialysis patients with an implantable cardioverter defibrillator

Patients receiving dialysis are at high risk for sudden cardiac death. Although clinical trials have shown that implantable cardioverter-defibrillators (ICDs) are effective in improving survival in a variety of populations, dialysis patients have been routinely excluded from these analyses. The purpose of this meta-analysis was to synthesize the available evidence regarding the effectiveness of ICD therapy in patients receiving dialysis. Medline, EMBASE, Web of Science, and Google Scholar were searched for pertinent studies published from 1999 to 2008. In addition, hand searches of the relevant annual scientific sessions and major scientific meetings in North America and Europe from 2000 to 2008 were performed. All clinical reports describing outcomes of ICD therapy in relation to renal function were eligible. Four investigators independently extracted the data in a standardized manner. Seven studies were identified, with a total of 2,516 patients and 89 patients receiving dialysis. Despite having ICDs, patients receiving dialysis had a 2.7-fold higher mortality compared with those not receiving dialysis. The results were similar in fixed- and random-effects models. Comparing patients receiving dialysis and those with chronic kidney disease but not receiving dialysis, there was no significant difference in mortality (risk ratio 1.62, 95% confidence interval 0.84 to 3.14). No evidence of publication bias was found. In conclusion, this meta-analysis suggests that even in those with ICDs, there is still a 2.7-fold increased mortality risk in patients who receive dialysis compared with those who do not. Beta blockers may be less cardioprotective in patients with ICDs who are on dialysis.