The relationship between glomerular filtration rate and survival in patients treated with an implantable cardioverter defibrillator

Influence of renal function on mortality and ventricular arrhythmias in patients undergoing first implantable cardioverter-defibrillator generator replacement

BACKGROUND

Impaired renal function is associated with increased mortality among patients with implantable cardioverter-defibrillators (ICDs). The relationship between renal function at time of ICD generator replacement and subsequent appropriate ICD therapies is not known.

METHODS AND RESULTS

We identified 441 patients who underwent first ICD generator replacement between 2000 and 2011 and had serum creatinine measured within 30 days of their procedure. Patients were divided into tertiles based on estimated glomerular filtration rate (eGFR). Adjusted Cox proportional hazard and competing risk models were used to assess relationships between eGFR and subsequent mortality and appropriate ICD therapy. Median eGFR was 37.6, 59.3, and 84.8 mL/min/1.73 m(2) for tertiles 1-3, respectively. Five-year Kaplan-Meier survival probability was 34.8%, 61.4%, and 84.5% for tertiles 1-3, respectively (P < 0.001). After multivariable adjustment, compared to tertile 3, worse eGFR tertile was associated with increased mortality (HR 2.84, 95% CI [1.36-5.94] for tertile 2; HR 3.84, 95% CI [1.81-8.12] for tertile 1). At 5 years, 57.0%, 58.1%, and 60.2% of patients remained free of appropriate ICD therapy in tertiles 1-3, respectively (P = 0.82). After adjustment, eGFR tertile was not associated with future appropriate ICD therapy. Results were unchanged in an adjusted competing risk model accounting for death.

CONCLUSIONS

At time of first ICD generator replacement, lower eGFR is associated with higher mortality, but not with appropriate ICD therapies. The poorer survival of ICD patients with reduced eGFR does not appear to be influenced by arrhythmia status, and there is no clear proarrhythmic effect of renal dysfunction, even after accounting for the competing risk of death.

Survival after primary prevention implantable cardioverter-defibrillator placement among patients with chronic kidney disease

BACKGROUND

Guidelines recommend that implantable cardioverter-defibrillator (ICD) candidates have an estimated longevity of ≥1 year. Longevity can be affected by chronic kidney disease (CKD).

METHODS AND RESULTS

Using the National Cardiovascular Data Registry ICD registry linked with the Social Security Death Master File, we assessed the rate of death after primary prevention ICD placement between January 1, 2006, and December 31, 2007, according to CKD stage. Using Cox models, we identified factors associated with death among patients with CKD. Compared with patients without CKD (n=26,056), those with CKD (n=21,226) were older, less commonly men, more often white, and more frequently had comorbid illness. Compared with patients without CKD, patients with a glomerular filtration rate 30 to 60, glomerular filtration rate <30, and end-stage renal disease on dialysis had a higher risk of death after ICD placement (hazard ratio, 2.08; 95% confidence interval, 1.99-2.18; P<0.0001; hazard ratio, 4.20; 95% confidence interval, 3.92-4.50; P<0.0001; and hazard ratio, 4.80; 95% confidence interval, 4.46-5.17; P<0.0001, respectively). Corresponding 1-year death rates were 4.4%, 9.1%, 20.2%, and 22.4%. Among patients with CKD, factors associated with increased risk of death included CKD severity, age >65 years, heart failure symptoms, diabetes mellitus, lung disease, serum sodium <140 mEq/L, atrial fibrillation or flutter, and a lower ejection fraction.

CONCLUSIONS

The risk of death after primary prevention ICD placement is proportional to CKD severity. Among patients with CKD, several factors are prognostically significant and could inform clinical decision making on primary prevention ICD candidacy.

Do implantable cardioverter defibrillators improve survival in patients with chronic kidney disease at high risk of sudden cardiac death? A meta-analysis of observational studies

AIMS

Prospective randomized clinical trials show that implantable cardioverter defibrillators (ICDs) can reduce the risk of total mortality in select populations. However, data regarding patients with chronic kidney disease (CKD) are inconclusive. The aim of this study was to evaluate if ICDs affect total mortality in CKD patients at high risk of sudden cardiac death.

METHODS AND RESULTS

Two separate meta-analyses were performed to (i) assess the effect of ICD on all-cause mortality in CKD patients at high risk of sudden cardiac death and (ii) assess the effect of CKD on all-cause mortality in patients who already had an ICD for primary or secondary prevention purposes. Medline and EMBASE were searched from 1966 to 2013. A manual search by cross-referencing was performed. Five observational studies with 17 460 CKD patients considered at high risk of sudden cardiac death were included to evaluate the effect of ICDs on patients with severe CKD. Patients with ICD implants had a reduction in all-cause mortality (adjusted hazard ratio (HR) = 0.65, 95% confidence interval (CI) = 0.47-0.91, P < 0.05) compared with a matched control group. Based on 15 observational studies with 5233 patients as part of our second comparison that evaluated the effect of CKD on patients who received an ICD, CKD was associated with higher mortality risk (HR = 2.86, 95% CI = 1.91-4.27, P < 0.05) despite an ICD.

CONCLUSION

The meta-analysis indicates that for patients undergoing ICD implant, CKD is associated with greater risk of dying. However, ICD placement reduces mortality in CKD patients at high risk of sudden cardiac death.

Predictors of mortality in patients with chronic kidney disease and an implantable defibrillator: an EPGEN substudy

AIMS

Chronic kidney disease (CKD) is increasingly prevalent, and is an independent risk factor for cardiovascular mortality. Clinical trials of the implantable cardioverter-defibrillator (ICD) have demonstrated a survival benefit over medical therapy for the prevention of sudden cardiac death, but its benefit in patients with concomitant CKD is unclear.

METHODS AND RESULTS

We studied 199 subjects with CKD, defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2), who underwent ICD implantation in the Duke Electrophysiology Genetic and Genomic Studies (EPGEN) biorepository. The mean age of the cohort was 67.8 ± 9.3 years, and the mean eGFR was 41.1 ± 13.2 mL/min/1.73 m(2). There were 63 deaths over a mean follow-up of 31.1 ± 18.8 months, corresponding to an annual mortality rate of 12.2%. Additionally, there was a 7% annual rate of appropriate ICD therapy. Using Cox regression analysis, older age, lower ejection fraction, and lower eGFR were found to be significant predictors of mortality. There was a gradient of risk associated with lower renal function: a 10 mL/min reduction in eGFR conferred a 48% increase in the risk of death (P < 0.001). Further adjustment for appropriate ICD therapy did not modify these associations.

CONCLUSION

In patients with CKD treated with a defibrillator, more advanced renal dysfunction is associated with reduced survival despite appropriate defibrillator therapy. This may be due to competing mortality risks in this population that attenuate the benefit of the ICD in reducing arrhythmic death. Age, ejection fraction, and kidney disease severity can be used to risk stratify patients before device implantation.

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.

Implantable cardioverter defibrillator therapy in chronic kidney disease: a meta-analysis

AIMS

Recent observational studies have shown that implantable cardioverter defibrillator (ICD) patients with chronic kidney disease (CKD) have increased mortality and therefore the value of device therapy in this group has been questioned. The purpose of this meta-analysis was to systematically analyse the effect of renal dysfunction on mortality of ICD patients.

METHODS AND RESULTS

Pubmed, Cochrane clinical trials database, and EMBASE were searched until December 2008. In addition, a manual search was performed using review articles, reference lists of papers, and abstracts from conference reports. Of the 90 initially identified studies, 11 observational studies with 3010 patients were analysed. The meta-analysis of these studies showed that CKD was associated with higher mortality risk (HR = 3.44, 95% CI 2.82-4.21, Z = 12.09, P < 0.001) while there were no significant differences between individual trials (P = 0.09, I(2) = 37.8%). A subgroup analysis which included the four studies that used estimated glomerular filtration rate (GFR) <60 mL/min/1.73 m(2) to define CKD showed a higher mortality in the CKD group as well (HR = 3.06, 95% CI 2.31-4.04, Z = 7.84, P < 0.001) without significant heterogeneity (P = 0.38, I(2) = 5.2%).

CONCLUSION

Our meta-analysis suggests that CKD is associated with increased mortality in patients who receive ICD therapy. Undoubtedly, prospective studies are needed in order to elucidate the impact of different stages of CKD in this setting. Given that the CKD prevalence is rapidly increasing, there is an imperative need for better risk stratification of ICD therapy candidates.

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.