Sudden cardiac death and acute myocardial infarction in dialysis patients: perspectives of a cardiologist

Defining Myocardial Infarction in trials of people receiving hemodialysis: consensus report from the SONG-HD MI Expert Working group

Cardiovascular disease is the leading cause of death in patients receiving hemodialysis. Currently there is no standardized definition of myocardial infarction (MI) for patients receiving hemodialysis. Through an international consensus process MI was established as the core CVD measure for this population in clinical trials. The Standardised Outcomes in Nephrology Group - Hemodialysis (SONG-HD) initiative convened a multidisciplinary, international working group to address the definition of MI in this population.Based on current evidence, the working group recommends using the 4th Universal Definition of MI with specific caveats with regard to the interpretation of "ischemic symptoms" and performing a baseline 12-lead electrocardiogram to facilitate interpretation of acute changes on subsequent tracings. The working group does not recommend obtaining baseline cardiac troponin values, though does recommend obtaining serial cardiac biomarkers in settings where ischemia is suspected. Application of an evidence-based uniform definition should increase the reliability and accuracy of trial results.

An atypical case of hemodialysis access stent migration

Endovascular stent fractures are commonly seen in arteries but are rare events in the venous system. Stents deployed in hemodialysis vascular accesses can fracture and migrate to proximal locations. Complications associated with stent fracture include in-stent stenosis and central vein stenosis. In this report, we present a unique case of a hemodialysis access stent fracture that migrated to the left ventricle and manifested with chest pain.

Isoflurane Preconditioning Protects the Myocardium Against Ischemia and Reperfusion Injury by Upregulating GRM1 Expression

BACKGROUND

Reduction in myocardial I/R injury has become the key to the therapy of ischemic cardiovascular disease. Isoflurane (ISO) preconditioning can mimic the major potent protective mechanisms and attenuate ischemia injury. Nevertheless, the mechanisms involved in the cardioprotective effects afforded by isoflurane preconditioning have never been evaluated systematically.

METHODS

Mice were randomly divided into an ISO preconditioning group and control group. The size of the infarcted region was measured, and comparisons between ISO preconditioning and control animals were made. The metabotropic glutamate receptor type 1(GRM1) expression levels in all groups were determined by quantitative PCR. GRM1 protein expression and DNA damage relative protein γ-H2AX were measured by western blot analysis. The oxidative stress was detected by immunofluorescence after staining with the Dihydroethidium (DHE).

RESULTS

ISO preconditioning significantly reduced the IR induced infarct volumes and reversed the GRM1 protein expression level in I/R induced myocardial injury. Moreover, ISO preconditioning has a protective effect in reducing the I/R induced DNA damage and oxidative stress.

CONCLUSION

The results of the present study have demonstrated that the expression of GRM1 provides a protective role in ISO preconditioning against I/R-induced myocardial infarction by reducing the oxidative stress and DNA damage.

MCP-1 promotes detrimental cardiac physiology, pulmonary edema, and death in the cpk model of polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by slowly expanding renal cysts that damage the kidney, typically resulting in renal failure by the fifth decade. The most common cause of death in these patients, however, is cardiovascular disease. Expanding cysts in PKD induce chronic kidney injury that is accompanied by immune cell infiltration, including macrophages, which we and others have shown can promote disease progression in PKD mouse models. Here, we show that monocyte chemoattractant protein-1 [MCP-1/chemokine (C-C motif) ligand 2 (CCL2)] is responsible for the majority of monocyte chemoattractant activity produced by renal PKD cells from both mice and humans. To test whether the absence of MCP-1 lowers renal macrophage concentration and slows disease progression, we generated genetic knockout (KO) of MCP-1 in a mouse model of PKD [congenital polycystic kidney (cpk) mice]. Cpk mice are born with rapidly expanding renal cysts, accompanied by a decline in kidney function and death by postnatal day 21. Here, we report that KO of MCP-1 in these mice increased survival, with some mice living past 3 mo. Surprisingly, however, there was no significant difference in renal macrophage concentration, nor was there improvement in cystic disease or kidney function. Examination of mice revealed cardiac hypertrophy in cpk mice, and measurement of cardiac electrical activity via ECG revealed repolarization abnormalities. MCP-1 KO did not affect the number of cardiac macrophages, nor did it alleviate the cardiac aberrancies. However, MCP-1 KO did prevent the development of pulmonary edema, which occurred in cpk mice, and promoted decreased resting heart rate and increased heart rate variability in both cpk and noncystic mice. These data suggest that in this mouse model of PKD, MCP-1 altered cardiac/pulmonary function and promoted death outside of its role as a macrophage chemoattractant.

Hemodialysis-induced cardiovascular disease

More than half of all deaths among end stage renal disease (ESRD) patients are due to cardiovascular disease (CVD). Cardiovascular changes secondary to renal dysfunction, including fluid overload, uremic cardiomyopathy, secondary hyperparathyroidism, anemia, altered lipid metabolism, and accumulation of gut microbiota-derived uremic toxins like trimethylamine N-oxidase, contribute to the high risk for CVD in the ESRD population. In addition, conventional hemodialysis (HD) itself poses myocardial stress and injury on the already compromised cardiovascular system in uremic patients. This review will provide an overview of cardiovascular changes in chronic kidney disease and ESRD, a description of reported mechanisms for HD-induced myocardial injury, comparison of HD with other treatment modalities in the context of CVD, and possible management strategies.

Cardiovascular impact in patients undergoing maintenance hemodialysis: Clinical management considerations

Patients undergoing maintenance hemodialysis develop both structural and functional cardiovascular abnormalities. Despite improvement of dialysis technology, cardiovascular mortality of this population remains high. The pathophysiological mechanisms of these changes are complex and not well understood. It has been postulated that several non-traditional, uremic-related risk factors, especially the long-term uremic state, which may affect the cardiovascular system. There are many cardiovascular changes that occur in chronic kidney disease including left ventricular hypertrophy, myocardial fibrosis, microvascular disease, accelerated atherosclerosis and arteriosclerosis. These structural and functional changes in patients receiving chronic dialysis make them more susceptible to myocardial ischemia. Hemodialysis itself may adversely affect the cardiovascular system due to non-physiologic fluid removal, leading to hemodynamic instability and initiation of systemic inflammation. In the past decade there has been growing awareness that pathophysiological mechanisms cause cardiovascular dysfunction in patients on chronic dialysis, and there are now pharmacological and non-pharmacological therapies that may improve the poor quality of life and high mortality rate that these patients experience.

How do We Manage Coronary Artery Disease in Patients with CKD and ESRD?

Chronic kidney disease (CKD) has been shown to be an independent risk factor for cardiovascular events. In addition, patients with pre-dialysis CKD appear to be more likely to die of heart disease than of kidney disease. CKD accelerates coronary artery atherosclerosis by several mechanisms, notably hypertension and dyslipidemia, both of which are known risk factors for coronary artery disease. In addition, CKD alters calcium and phosphorus homeostasis, resulting in hypercalcemia and vascular calcification, including the coronary arteries. Mortality of patients on long-term dialysis therapy is high, with age-adjusted mortality rates of about 25% annually. Because the majority of deaths are caused by cardiovascular disease, routine cardiac catheterization of new dialysis patients was proposed as a means of improving the identification and treatment of high-risk patients. However, clinicians may be uncomfortable exposing asymptomatic patients to such invasive procedures like cardiac catheterization, thus noninvasive cardiac risk stratification was investigated widely as a more palatable alternative to routine diagnostic catheterization. The effective management of coronary artery disease is of paramount importance in uremic patients. The applicability of diagnostic, preventive, and treatment modalities developed in nonuremic populations to patients with kidney failure cannot necessarily be extrapolated from clinical studies in non-kidney failure populations. Noninvasive diagnostic testing in uremic patients is less accurate than in nonuremic populations. Initial data suggest that dobutamine echocardiography may be the preferred diagnostic method. PCI with stenting is a less favorable alternative to CABG, however, it has a faster recovery time, reduced invasiveness, and no overall mortality difference in nondiabetic and non-CKD patients compared with CABG. CABG is associated with reduced repeat revascularizations, greater relief of angina, and increased long term survival. However, CABG is associated with a higher incidence of post-operative risks. The treatment chosen for each patient should be an individualized decision based upon numerous risk factors. CKD is associated with higher rates of CAD, with 44% of all-cause mortality attributable to cardiac disease and about 20% from acute MI. Optimal treatment including aggressive lifestyle modifications and concomitant medical therapy should be implemented in all patients to maximize benefits from either PCI or CABG. Future prospective randomized controlled trials with newer second or third generation DES and bioabsorbable DES are necessary to determine if PCI may be non-inferior to CABG in the future.

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.

Near-term prediction of sudden cardiac death in older hemodialysis patients using electronic health records

BACKGROUND AND OBJECTIVES

Sudden cardiac death is the most common cause of death among individuals undergoing hemodialysis. The epidemiology of sudden cardiac death has been well studied, and efforts are shifting to risk assessment. This study aimed to test whether assessment of acute changes during hemodialysis that are captured in electronic health records improved risk assessment.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data were collected from all hemodialysis sessions of patients 66 years and older receiving hemodialysis from a large national dialysis provider between 2004 and 2008. The primary outcome of interest was sudden cardiac death the day of or day after a dialysis session. This study used data from 2004 to 2006 as the training set and data from 2007 to 2008 as the validation set. The machine learning algorithm, Random Forests, was used to derive the prediction model.

RESULTS

In 22 million sessions, 898 people between 2004 and 2006 and 826 people between 2007 and 2008 died on the day of or day after a dialysis session that was serving as a training or test data session, respectively. A reasonably strong predictor was derived using just predialysis information (concordance statistic=0.782), which showed modest but significant improvement after inclusion of postdialysis information (concordance statistic=0.799, P<0.001). However, risk prediction decreased the farther out that it was forecasted (up to 1 year), and postdialytic information became less important.

CONCLUSION

Subtle changes in the experience of hemodialysis aid in the assessment of sudden cardiac death and are captured by modern electronic health records. The collected data are better for the assessment of near-term risk as opposed to longer-term risk.

Low plasma α-tocopherol concentrations and adverse clinical outcomes in diabetic hemodialysis patients

BACKGROUND AND OBJECTIVES

Trials with the antioxidant vitamin E have failed to show benefit in the general population. Considering the different causes of death in ESRD, this study investigated the association between plasma concentrations of α-tocopherol and specific clinical outcomes in diabetic hemodialysis patients.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

In 1046 diabetic hemodialysis patients (participants of the German Diabetes and Dialysis Study), α-tocopherol was measured in plasma by reversed-phase HPLC. By Cox regression analyses, hazard ratios were determined for prespecified end points according to baseline plasma α-tocopherol levels: sudden death (n=134), myocardial infarction (n=172), stroke (n=89), combined cardiovascular events (n=398), fatal infection (n=107), and all-cause mortality (n=508).

RESULTS

Patients had a mean age of 66±8 years, and mean plasma α-tocopherol level was 22.8±9.6 µmol/L. Levels of α-tocopherol were highly correlated to triglycerides (r=0.63, P<0.001). Patients in the lowest α-tocopherol quartile had (in unadjusted analyses) a 79% higher risk of stroke and a 31% higher risk of all-cause mortality compared with patients in the highest quartile. The associations were attenuated after adjustment for confounders (hazard ratiostroke=1.56, 95% confidence interval=0.75-3.25; hazard ratiomortality=1.22, 95% confidence interval=0.89-1.69, respectively). There was no association between α-tocopherol and myocardial infarction, sudden death, or infectious death.

CONCLUSIONS

Plasma α-tocopherol concentrations were not independently associated with cardiovascular outcomes, infectious deaths, or all-cause mortality in diabetic hemodialysis patients. The lack of association can partly be explained by a confounding influence of malnutrition, which should be considered in the planning of trials to reduce cardiovascular risk in dialysis patients.

Myocardial Stunning with Hemodialysis: Clinical Challenges of the Cardiorenal Patient

We discuss the current state of knowledge related to the pathogenesis of myocardial stunning as well as the potential mechanisms responsible for the clinical presentation of myocardial stunning in hemodialysis patients. We suggest future research areas for this critical and clinically important condition in this high-risk patient population. In consideration of acute and chronic changes secondary to dialysis, especially in patients with risk for coronary artery disease, the prevalence of myocardial stunning and its role in the natural history of these patients' disease progression is considered. We propose a paradigm: that the majority of the pathophysiologic mechanisms by which hemodialysis may induce myocardial stunning falls into two categories with (1) vascular and/or (2) metabolic contributions. In order to prevent eventual myocardial hibernation, myocardial remodeling, scarring, and loss of contractile function with aberrant electrical conductivity that could lead to sudden death, it is imperative to identify the risk factors associated with myocardial stunning during hemodialysis. Further understanding of these mechanisms may lead to novel clinical interventions and pharmacologic therapeutic agents.

Cardiac catheterization in the dialysis population in 2012: we know more, but much remains unknown

Chronic kidney disease is now widely accepted as an independent risk factor for coronary disease and the dialysis population may represent the highest risk subgroup. Among all dialysis patients, a cardiac cause of mortality has been estimated at 40%. In addition, prior studies have demonstrated that when cardiac catheterization is obtained in a consecutive series of asymptomatic diabetic patients on dialysis the rates of coronary disease can approach 50%. However, the ability to define the problem continues to be greater than the ability to treat or prevent it. Coronary revascularization strategies have limitations in the general population which are amplified in the dialysis population. The ability to accurately diagnose an acute coronary syndrome is more difficult, clinical outcomes have a smaller margin of benefit, and technical challenges result in higher complication rates. Recent data demonstrate an inverse relationship between glomerular filtration rate and the risk of presenting with an acute myocardial infarction rather than unstable angina suggesting that patients with CKD may have a unique pathophysiologic profile that is more prone to plaque rupture. However, these "vulnerable" plaques typically are associated with stenoses <50% prior to rupture and are thus poor targets for revascularization and perhaps best treated with medical therapy. Although the benefits of revascularization may continue to outweigh the risks in the context of acute coronary syndromes, preventive strategies would have to overcome the lower margin of benefit and higher complication rates.

Cardiovascular Mortality in Hemodialysis Patients: Clinical and Epidemiological Analysis

Cardiovascular diseases are the leading cause of death in hemodialysis (HD) patients. The annual cardiovascular mortality rate in these patients is 9%, with left ventricular (LV) hypertrophy, ischemic heart disease and heart failure being the most prevalent causes of death. The aim of this study was to determine the cardiovascular mortality rate and estimate the influence of risk factors on cardiovascular mortality in HD patients. A total of 115 patients undergoing HD for at least 6 months were investigated. Initially a cross-sectional study was performed, followed by a two-year follow-up study. Beside the standard biochemical parameters, C-reactive protein (CRP), homocysteine, cardiac troponins (cTn) and the echocardiographic parameters of LV morphology and function (LV mass index, LV fractional shortening, LV ejection fraction) were determined. Results were analyzed using Cox regression analysis, Kaplan-Meier and Log-Rank tests. The average one-year cardiovascular mortality rate was 8.51%. Multivariate Cox regression analysis identified increased CRP, cTn T and I, and LV mass index as independent risk factors for cardiovascular mortality. Patients with cTnT > 0.10 ng/mL and CRP > 10 mg/L had significantly higher cardiovascular mortality risk (p < 0.01) than patients with cTnT > 0.10 ng/mL and CRP ≤ 10 mg/L and those with cTnT ≤ 0.10 ng/mL and CRP ≤ 10 mg/L (p < 0.01). HD patients with high cTnT and CRP have a higher cardiovascular mortality risk.

β-Blockers for prevention of sudden cardiac death in patients on hemodialysis: a propensity score analysis of the HEMO Study

BACKGROUND

Hemodialysis patients have an elevated risk of sudden cardiac death. Although the efficacy of β-blockers for the prevention of sudden cardiac death has been proven in the general population, little evidence exists in patients with kidney failure.

STUDY DESIGN

Post hoc analysis of the Hemodialysis (HEMO) Study.

SETTING & PARTICIPANTS

Participants enrolled in the HEMO Study from May 1995 to February 2001.

INTERVENTION

β-Blocker use ascertained through self-reported questionnaires and dialysis clinic charts.

OUTCOMES

Sudden cardiac death adjudicated by a committee as a secondary outcome of interest.

MEASUREMENTS

We used Cox proportional hazards regression models, competing risk survival analysis, propensity score matching, and covariate adjustment to study the association of β-blockers with sudden cardiac death.

RESULTS

1,747 patients were included in this study, and 521 were on β-blocker therapy at baseline. Mean age was 58 years, 57% were women, and 39% had ischemic heart disease (IHD) at baseline. Baseline β-blocker use was not associated with lower risk of sudden cardiac death in univariate (cause-specific HR, 0.89; 95% CI, 0.64-1.24), multivariable (cause-specific HR, 0.87; 95% CI, 0.62-1.22), or propensity-matched (cause-specific HR, 0.91; 95% CI, 0.55-1.50) analyses. There was a significant interaction between β-blocker use and sudden cardiac death (interaction P = 0.03) in patients with (cause-specific HR, 0.65; 95% CI, 0.42-1.01) and without IHD (cause-specific HR, 1.61; 95% CI, 0.92-2.80).

LIMITATIONS

Observational nature of the study.

CONCLUSIONS

In hemodialysis patients without preexisting IHD, β-blocker use was not associated with lower risk of sudden cardiac death. However, there was a trend toward benefit in those with IHD.

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.

Cardiac troponins: outcome predictors in hemodialysis patients

Cardiovascular diseases represent the main cause of death in hemodialysis (HD) patients. Cardiac troponins (cTnT and cTnI) are indicators of myocardial damage. The aims of this study were to assess the prevalence of increased serum cTn in the absence of acute coronary syndrome, to determine overall and cardiovascular mortality rates, and to investigate the possible predictive values of cTnT and cTnI on the outcome in HD patients over a 2-year follow-up period. The study included 115 patients (71 men and 44 women) with an average age of 53.30 +/- 12.17 years who had undergone regular HD for 4.51 +/- 4.01 years and had a mean HD adequacy (Kt/Vsp) of 1.17 +/- 0.23. Increased serum cTnT concentration was found in 37.39% of patients and elevated serum cTnI concentration was present in 11.30% of HD patients without symptoms or signs of acute coronary syndrome. The average 2-year mortality rate was 13.74% and the average 2-year cardiovascular mortality rate was 8.51%. Patients with serum cTnT levels greater than 0.10 ng/ml had significantly lower overall and cardiovascular survival rates than patients with serum cTnT levels of less than 0.10 ng/ml. Patients with serum cTnI levels greater than 0.15 ng/ml had significantly lower overall and cardiovascular survival rates than patients with serum cTnI of less than 0.15 ng/ml. In patients on regular HD, cTn levels are significant outcome predictors.

One-year clinical outcomes of dialysis patients after implantation with sirolimus-eluting coronary stents

BACKGROUND

The efficacy of sirolimus-eluting stents (SESs) has not been established in dialysis patients.

METHODS AND RESULTS

This study was a non-randomized observational single-center registry in a community hospital: data for 80 consecutive dialysis patients who underwent percutaneous coronary intervention (PCI) with SES were compared with those of a historical group of consecutive 124 dialysis patients treated with bare-metal stents (BMS). After 1 year, the cumulative incidence of major adverse cardiac events (MACE), comprising cardiac death, nonfatal myocardial infarction, stent thrombosis, or target lesion revascularization (TLR), was 25.2% in the SES group and 38.2% in the BMS group (p=0.048). In multivariate analysis, use of SES remained an independent predictor of MACE at 1 year after PCI (risk ratio 0.70, 95% confidence interval 0.52-0.93, p=0.015). Rates of TLR were 21.7% in the SES group and 30.9% in the BMS group and (p=0.15). Subgroup analysis showed that use of SES was effective in patients with small vessels, non-diabetic patients, and patients without highly calcified lesions.

CONCLUSIONS

In dialysis patients, the implantation of SES was moderately effective in reducing MACE at 1 year after PCI as compared with BMS. However, the TLR rate at 1 year was relatively higher than previously reported.

Chronic kidney disease is associated with increased risk of sudden cardiac death among patients with coronary artery disease

Sudden cardiac death is the most common cause of mortality among patients with end-stage kidney disease maintained on hemodialysis. To examine whether this increased risk is also seen with less advanced kidney disease, we studied the relationship between glomerular filtration rate and risk of sudden cardiac death in patients with moderate kidney disease and known coronary artery disease. This retrospective longitudinal study encompassed 19,440 consecutive patients who underwent cardiac catheterization at a single academic institution. There were 522 adjudicated sudden cardiac death events, yielding an overall rate of 4.6 events per 1000 patient years. This figure reflected rates of 3.8 events in 14,652 patients with estimated glomerular filtration rates (eGFR) > or =60 (stage 2 CKD or better) and 7.9 events in 4788 patients with glomerular filtration rates <60 (stage 3-5 CKD), all normalized to 1000 patient-years. After adjusting for differences in known cardiac risk factors and other covariates in a multivariate Cox proportional hazards model, the eGFR was independently associated with sudden cardiac death (hazard ratio (HR)=1.11 per 10 ml/min decline in the eGFR). Our analysis found that reductions in the eGFR in CKD stages 3-5 are associated with a progressive increase in risk of sudden cardiac death in patients with coronary artery disease. Additional studies are needed to better characterize the mechanisms by which reduced kidney function increases this risk.

Nocturnal home hemodialysis improves baroreflex effectiveness index of end-stage renal disease patients

BACKGROUND

In patients with end-stage renal disease receiving conventional hemodialysis, both the frequency with which brief rises or falls in systolic blood pressure initiate concordant changes in pulse interval (arterial baroreflex effectiveness index), and the gain of reflex heart rate responses to these stimuli (arterial baroreflex sensitivity) are diminished. In chronic renal failure, low baroreflex effectiveness index and baroreflex sensitivity are associated with increased rates of all-cause mortality and sudden death, respectively. Conversion to home nocturnal hemodialysis augments baroreflex sensitivity but its effects on baroreflex effectiveness index have not been reported.

METHODS

In 20 consecutive hypertensive conventional hemodialysis patients training to transition to nocturnal hemodialysis (age 41 +/- 2 years; mean +/- standard error), baroreflex effectiveness index, baroreflex sensitivity (sequence method) and total arterial compliance (stroke volume/pulse pressure) were determined during quiet rest before and 2 months after conversion.

RESULTS

With nocturnal hemodialysis, dialysis frequency doubled, the dose per session increased by 70% and antihypertensive medications were withdrawn (from 2.5 +/- 0.3 to 0.2 +/- 0.1 drugs/patient, P < 0.01) because systolic blood pressure fell (from 139 +/- 5 to 119 +/- 4 mmHg, P < 0.05). Baroreflex effectiveness index increased from (0.33 +/- 0.03 to 0.42 +/- 0.03, P = 0.01). Baroreflex sensitivity increased from 5.60 +/- 0.88 to 8.48 +/- 1.60 ms/mmHg (P < 0.05). Changes in total arterial compliance correlated with changes in baroreflex sensitivity (r = 0.63, P = 0.004) but not baroreflex effectiveness index (r = 0.05, P = 0.95), suggesting independent mechanisms for their attenuation and recovery in end-stage renal disease.

CONCLUSION

Nocturnal hemodialysis increases baroreflex effectiveness index in addition to baroreflex sensitivity. The hypothesis that such changes might reduce cardiovascular event rates in this high-risk population merits prospective evaluation. More frequent engagement of the arterial baroreflex after conversion to nocturnal hemodialysis may improve short-term cardiovascular regulation.

The association of sudden cardiac death with inflammation and other traditional risk factors

Despite the frequency of cardiovascular death in dialysis patients, few studies have prospectively measured sudden cardiac death in these individuals. Here, we sought to determine the frequency of sudden cardiac death and its association with inflammation and other risk factors among the CHOICE (Choices for Healthy Outcomes In Caring for ESRD) cohort of 1,041 incident dialysis patients. Sudden cardiac death was defined as that occurring outside of the hospital with an underlying cardiac cause from death certificate data. Over a median 2.5 years of follow-up, 22% of all mortality in this cohort was due to sudden cardiac death. Using Cox proportional hazards, we found that the highest tertiles of high-sensitivity C-reactive protein and of IL-6 were each associated with twice the risk of sudden cardiac death compared to their lowest tertiles when adjusted for demographics, comorbidities and laboratory factors. A decrement in serum albumin was associated with a 1.35 times increased risk for sudden cardiac death in the highest compared to the lowest tertile. These findings were robust and consistent when accounting for competing risks of death from other causes. Hence, we found that sudden cardiac death is common among patients with end stage renal disease and that inflammation and malnutrition significantly increased its occurrence independent of traditional cardiovascular risk factors.

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

OBJECTIVE

Sudden cardiac (arrhythmic) death (SCD) is the single largest cause of death in dialysis patients. Prophylactic Implantable Cardioverter Defibrillator (ICD) therapy reduces SCD and reduces all-cause mortality in several groups of patients at high risk for arrhythmic death. Whether this also applies to dialysis patients is unknown.

RESEARCH DESIGN AND METHODS

The Implantable Cardioverter Defibrillator in Dialysis patients (ICD2) trial is a prospective randomised controlled study. It has been designed to evaluate the efficacy and safety of prophylactic ICD therapy in reducing sudden cardiac death rates in dialysis patients aged 55-80 years. A total of 200 patients will be included. The primary endpoint of the study is sudden cardiac (arrhythmic) death. The mean follow-up time will be 4 years.

TRIAL REGISTRATION

'The Netherlands Trial Register'--ISRCTN20479861

CONCLUSION

The ICD2 trial--a pilot study--will be the first study to evaluate the possible benefit of ICD therapy for the primary prevention of sudden cardiac death in dialysis patients.

Simvastatin for secondary prevention of all-cause mortality and major coronary events in patients with mild chronic renal insufficiency

BACKGROUND

A potentially modifiable risk factor for cardiovascular disease in patients with mild chronic renal insufficiency is dyslipidemia. Few studies examined the effects of statins on all-cause mortality and major coronary events in patients with renal dysfunction.

METHODS

We performed a post hoc analysis from the Randomized Trial of Cholesterol Lowering in 4,444 Patients with Coronary Heart Disease: The Scandinavian Simvastatin Survival Study. Of 4,444 participants, 2,314 (52.1%) had mild chronic renal insufficiency defined as an estimated glomerular filtration rate less than 75 mL/min/1.73 m(2) (<1.25 mL/s), measured using the Modification of Diet in Renal Disease equation. The primary end point was all-cause mortality.

RESULTS

During the follow-up period, simvastatin use was associated with decreased all-cause mortality (adjusted hazard ratio [HR], 0.69; confidence interval [CI], 0.54 to 0.89) in the 2,314 participants with mild chronic renal insufficiency. Rates of major coronary events (adjusted HR, 0.67; CI, 0.56 to 0.79) and coronary revascularization (adjusted HR, 0.62; CI, 0.49 to 0.77) also were significantly lower in the simvastatin group. No significant decreases in stroke incidence were observed in the simvastatin group (adjusted HR, 0.88; CI, 0.55 to 1.39). The side-effect profile was similar between the 2 treatment groups.

CONCLUSION

Simvastatin therapy appears to be effective and safe for the secondary prevention of all-cause mortality and major coronary events in patients with mild chronic renal dysfunction.