Electrocardiographic abnormalities and uremic cardiomyopathy

Left ventricular geometry and cardiovascular mortality based on haemodialysis patient autopsy analyses

AIM

In end-stage renal disease (ESRD) patients, left ventricular hypertrophy (LVH) is common and a risk for cardiovascular events. LVH is geometrically classified into two major groups, concentric and eccentric, and accumulating evidence suggests eccentric LVH has a more negative effect than concentric LVH on ESRD outcome. However, there have been very few studies on the cardiac findings from ESRD patient autopsy in which the relationship between LVH geometry and mortality was analyzed.

METHODS

An observational study was performed with the autopsy findings in 30 haemodialysis patient cases between 2001 and 2006 at Mitsui Memorial Hospital, Tokyo. Between those who died of a cardiovascular cause and those who died of non-cardiovascular causes, we compared the heart/bodyweight ratio, left ventricular dilatation, and the extent of fibrosis of the left ventricle.

RESULTS

Heart/bodyweight ratio was significantly higher (P < 0.0001) in the cardiovascular mortality group (n = 11, 11.7 +/- 2.5 g/kg) compared to the non-cardiac cause of death group (n = 19, 8.05 +/- 0.7 g/kg). The dilatation of the left ventricle was significantly more frequent in the cardiovascular than the non-cardiac cause of death group (P = 0.016). Additionally, the fibrotic area of left ventricular cross-section was larger in the cardiovascular (1.63 +/- 1.6%) than the non-cardiac group (0.83 +/- 1.7%, P = 0.04).

CONCLUSION

This autopsy study indicates that eccentric LVH in haemodialysis patients is closely associated with cardiovascular mortality. LVH geometry, as well as LVH severity, is worthy of consideration as a clinical predictor for cardiovascular mortality.

QT prolongation is an independent predictor of mortality in end-stage renal disease

BACKGROUND

Coronary artery disease (CAD) is the predominant cause of sudden cardiac death in the general population, and sudden cardiac death is the leading cause of mortality in end-stage renal disease (ESRD).

HYPOTHESIS

QT-interval prolongation is an independent prognosticator in ESRD.

METHODS

We reviewed clinical, electrocardiographic, stress test, and coronary angiography data on ESRD patients evaluated for transplantation at our institution between 2000 and 2004 who underwent coronary angiography. The QT interval was corrected for heart rate and QRS duration (QTc). All-cause mortality data were prospectively collected and verified against the Social Security Death Index database.

RESULTS

During 40 +/- 28 months of follow-up, 132 of the 280 (47%) patients died prior to renal transplantation. Patients with a prolonged QTc (39%) had 1-, 3-, and 5-year death-rates of 12%, 36%, and 47%, respectively, vs 8%, 24%, and 36% for those with normal QTc (log-rank P = 0.03). In a multivariate Cox regression model that adjusted for age, gender, diabetes mellitus, myocardial infarction, presence and severity of CAD on angiography, left ventricular (LV) hypertrophy, LV ejection fraction (EF), and multiple other variables, QTc remained to be an independent predictor of survival (hazard ratio [HR]: 1.008, 95% confidence interval [CI]: 1.001-1.014, P = 0.016). Female gender, decreasing LVEF, and decreasing severity of CAD on angiography were independent predictors of prolonged QTc.

CONCLUSIONS

QTc prolongation is an independent predictor of mortality in ESRD patients being evaluated for renal transplantation. The prognostic information gained from the QTc is additive to that provided by the LVEF and the severity of CAD.

Ventricular arrhythmia in incident kidney transplant recipients: prevalence and associated factors

Cardiovascular mortality in kidney transplant recipients has shown to be substantially elevated particularly in the first year of transplantation. Complex ventricular arrhythmia (VA) has been pointed as one of the etiologies of sudden death. The aim of this study was to evaluate the prevalence of VA and to investigate the factors associated with their occurrence in incident kidney transplant recipients. A total of 100 incident kidney transplant recipients were included in the study (39.7 ± 10.1 years, 55% male, 43.6 ± 10.1 days of transplantation, 66% living donors). All the patients underwent 24 h electrocardiogram, echocardiogram and multi-slice computed tomography. Thirty percent of the patients had VA. Left ventricular hypertrophy was observed in 57% of the patients while heart failure was found in 5%. Coronary artery calcification (CAC) was observed in 26 patients, from which 31% had severe calcification. The group of patients with VA was predominantly male, had been on dialysis therapy for a longer time and had more coronary calcification. In the multiple logistic regression analysis, male gender and CAC score were independently associated with the presence of VA. In conclusion, kidney transplant recipients exhibited a high prevalence of VA and the factors associated with its occurrence were the male gender and the presence of CAC.

Left ventricular hypertrophy in new hemodialysis patients without symptomatic cardiac disease

BACKGROUND AND OBJECTIVES

Although left ventricular hypertrophy (LVH) is a characteristic finding in hemodialysis (HD) populations, few risk factors for progressive LVH have been identified.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

As part of a multinational, blinded, randomized, controlled trial that demonstrated no effect of hemoglobin targets on LV size, 596 incident HD patients, without symptomatic cardiac disease or cardiac dilation, had baseline echocardiograms within 18 months of starting dialysis and subsequently at 24, 48, and 96 weeks later. A wide array of baseline risk factors were assessed, as were BP and hemoglobin levels during the trial.

RESULTS

The median age and duration of dialysis were 51.5 years and 9 months, respectively. LV mass index (LVMI) rose substantially during follow-up (114.2 g/m(2) at baseline, 121 at week 48, 123.4 at week 48, and 128.3 at week 96), as did fractional shortening, whereas LV volume (68.7, 70.1, 68.7, and 68.1 ml/m(2)) and E/A ratio remained unchanged. At baseline, the only multivariate associations of LVMI were gender and N terminal pro-B type natriuretic peptide. Comparing first and last echocardiograms in those without LVH at baseline, independent predictors of increase in LVMI were higher time-integrated systolic BP and cause of ESRD. An unadjusted association between baseline LVMI and subsequent cardiovascular events or death was eliminated by adjusting for age, diabetes, systolic BP, and N terminal pro-B type natriuretic peptide.

CONCLUSIONS

Progressive concentric LVH and hyperkinesis occur in HD patients, which is partly explained by hypertension but not by a wide array of potential risk factors, including anemia.

Association of left atrial volume with mortality among ESRD patients with left ventricular hypertrophy referred for kidney transplantation

BACKGROUND

Left ventricular hypertrophy (LVH) is common in patients with end-stage renal disease (ESRD) and an independent risk factor for premature cardiovascular death. Left atrial volume (LAV), measured using echocardiography, predicts death in patients with ESRD. Cardiovascular magnetic resonance (CMR) imaging is a volume-independent method of accurately assessing cardiac structure and function in patients with ESRD.

STUDY DESIGN

Single-center prospective observational study to assess the determinants of all-cause mortality, particularly LAV, in a cohort of ESRD patients with LVH, defined using CMR imaging.

SETTING & PARTICIPANTS

201 consecutive ESRD patients with LVH (72.1% men; mean age, 51.6 +/- 11.7 years) who had undergone pretransplant cardiovascular assessment were identified using CMR imaging between 2002-2008. LVH was defined as left ventricular mass index >84.1 g/m(2) (men) or >74.6 g/m(2) (women) based on published normal left ventricle dimensions for CMR imaging. Maximal LAV was calculated using the biplane area-length method at the end of left ventricle systole and corrected for body surface area.

PREDICTORS

CMR abnormalities, including LAV.

OUTCOME

All-cause mortality.

RESULTS

54 patients died (11 after transplant) during a median follow-up of 3.62 years. Median LAV was 30.4 mL/m(2) (interquartile range, 26.2-58.1). Patients were grouped into high (median or higher) or low (less than median) LAV. There were no significant differences in heart rate and mitral valve Doppler early to late atrial peak velocity ratio. Increased LAV was associated with higher mortality. Kaplan-Meier survival analysis showed poorer survival in patients with higher LAV (log rank P = 0.01). High LAV and left ventricular systolic dysfunction conferred similar risk and were independent predictors of death using multivariate analysis.

LIMITATIONS

Only patients undergoing pretransplant cardiac assessment are included. Limited assessment of left ventricular diastolic function.

CONCLUSIONS

Higher LAV and left ventricular systolic dysfunction are independent predictors of death in ESRD patients with LVH.

Imatinib ameliorates fibrosis in uraemic cardiac disease in BALB/c without improving cardiac function

BACKGROUND

Cardiovascular disease is one of the major causes of mortality and morbidity in patients with end-stage renal disease (ESRD). It is characterized by multiple left ventricular abnormalities, referred to as 'uraemic cardiomyopathy'. The aim of the study was to investigate uraemic cardiac disease in a mouse model of chronic renal failure induced by subtotal nephrectomy and to evaluate the impact of the tyrosine kinase inhibitor imatinib and its antifibrotic as well as functional properties on the extent of the disease.

METHODS

Male BALB/c mice were sham operated (SH) or subtotally nephrectomized and either left untreated (5/6) or treated with imatinib (5/6+I: 10 mg/kg/day p.o.) for up to 24 weeks. Cardiac and arterial structure and function were analysed using echocardiography, histology, extent of lipid peroxidation and myography, respectively.

RESULTS

Subtotal nephrectomy resulted in cardiac dysfunction characterized by reduced fractional shortening (SH: 21.6 +/- 4.7%; 5/6: 11.1 +/- 2.4%; 5/6+I: 8.4 +/- 2.7%; P < 0.05) and ejection fraction (SH: 38.8 +/- 4.5%; 5/6: 26.1 +/- 2.8%; 5/6+I: 18.6 +/- 2.6%; P < 0.05) after 24 weeks. This was associated with impaired endothelium-dependent vasodilatation in mesenteric resistance vessels and elevated cardiac malondialdehyde concentrations as a marker of lipid peroxidation. In this model, the continuous application of the tyrosine kinase inhibitor imatinib was associated with less myocardial fibrosis (SH: 2.52 +/- 0.34%; 5/6: 5.50 +/- 0.18%; 5/6+I: 3.52 +/- 0.52%; P < 0.05), but did not preserve myocardial function.

CONCLUSIONS

Uraemic cardiac disease in BALB/c results in fibrosis, oxidative damage and endothelial dysfunction. However, the anti-fibrotic activity of imatinib did not ameliorate cardiac dysfunction. Thus, our data suggest that uraemic cardiac disease in this mouse model is driven by oxidative damage and endothelial dysfunction.

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.

Uremic cardiac hypertrophy is reversed by rapamycin but not by lowering of blood pressure

Chronic kidney disease is often complicated by uremic cardiomyopathy that consists of left ventricular hypertrophy and interstitial fibrosis. It is thought that hypertension and volume overload are major causes of this disease, but here we sought to identify additional mechanisms using a mouse model of chronic renal insufficiency. Mice with a remnant kidney developed an elevated blood urea nitrogen by 1 week, as expected, and showed progressive cardiac hypertrophy and fibrosis at 4 and 8 weeks even though their blood pressures were not elevated nor did they show signs of volume overload. Cardiac extracellular signal-regulated kinase (ERK) was activated in the uremic animals at 8 weeks. There was also an increased phosphorylation of S6 kinase, which is often mediated by activation of the mammalian target of rapamycin (mTOR). To test the involvement of this pathway, we treated these uremic mice with rapamycin and found that it reduced cardiac hypertrophy. Reduction of blood pressure, however, by hydralazine had no effect. These studies suggest that uremic cardiomyopathy is mediated by activation of a pathway that involves the mTOR pathway.

Cardiovascular disease in patients with renal disease: the role of statins

OBJECTIVES

Atherosclerosis is common in patients with chronic kidney disease (CKD), and cardiovascular disease (CVD) represents a major cause of death. The National Kidney Foundation guidelines favour the use of statin therapy for treatment of dyslipidaemia in patients with CKD. Much evidence supports statin therapy for reducing CVD and improving outcomes in the general population, but there is less evidence in patients with CKD. Consequently, prevention of CVD in CKD is based primarily on extrapolation from non-CKD trials. Significantly, in trials specifically designed to investigate patients with CKD, evidence is emerging for improved cardiovascular outcomes with statin therapy. This review describes available data relating to cardiovascular outcomes and the role of statins in patients with CKD, including pre-dialysis, dialysis, and renal transplant patients.

RESEARCH DESIGN AND METHODS

The PubMed database was searched (1998-present) to ensure comprehensive identification of publications (including randomised clinical trials) relevant to CKD patients, patterns of cardiovascular outcome in such patients and their relationship to lipid profile, and the role of statins for the prevention and treatment of cardiovascular complications.

RESULTS

There are conflicting data on the relationship between dyslipidaemia and cardiovascular outcomes, with one major study of statin therapy (4D--Deutsche Diabetes Dialyse Studie) providing equivocal results. Further studies, including AURORA (A study to evaluate the Use of Rosuvastatin in subjects On Regular haemodialysis: an Assessment of survival and cardiovascular events; NCT00240331) in patients receiving haemodialysis, and SHARP (Study of Heart And Renal Protection; NCT00125593) in patients with CKD including those on dialysis, should help to clarify the role of statin therapy in these populations.

CONCLUSIONS

More studies are needed to elucidate the role of statins in improving cardiovascular outcomes for CKD patients. It is anticipated that ongoing clinical trials geared towards the optimal prevention and treatment of CVD in patients with CKD will help guide clinicians in the management of CKD.

Left ventricular hypertrophy in mild and moderate reduction in kidney function determined using cardiac magnetic resonance imaging and cystatin C: the multi-ethnic study of atherosclerosis (MESA)

BACKGROUND

Left ventricular (LV) hypertrophy (LVH) is associated with chronic kidney disease, but the association of LVH with a mild decrease in kidney function is not known. We hypothesized that mild and moderate decreases in kidney function, reflected in greater serum cystatin C concentrations, would be linearly associated with a greater prevalence of LVH.

STUDY DESIGN

Cross-sectional observational study.

SETTINGS & PARTICIPANTS

Participants in baseline examinations in the Multi-Ethnic Study of Atherosclerosis (MESA), a population-based study with several sites in the United States.

PREDICTORS

Cystatin C-based estimated glomerular filtration rate (eGFR(cysC)) and creatinine-based eGFR.

OUTCOMES

LVH and LV mass index.

MEASUREMENTS

Serum cystatin C and creatinine, LV mass obtained by using magnetic resonance imaging. LVH cutoff values for men and women were defined by the upper 95th percentile of LV mass index of all MESA participants without hypertension.

RESULTS

Of the 4,971 participants analyzed, mean creatinine-based eGFR was 81 +/- 17 (SD) mL/min/1.73 m(2) and mean eGFR(cysC) was 94 +/- 32 mL/min/1.73 m(2). LVH was distinctly more prevalent (>12%) in only the lowest 2 deciles of eGFR(cysC) (<75 mL/min/1.73 m(2)). When 435 participants (9%) with stage 3 or higher chronic kidney disease (creatinine-based eGFR < 60 mL/min/1.73 m(2)) were excluded, the odds for LVH increased for each lower category of eGFR(cysC) less than 75 mL/min/1.73 m(2): odds ratio 1.6 for LVH with eGFR(cysC) of 60 to 75 mL/min/1.73 m(2) (95% confidence interval, 1.20 to 2.07; P = 0.001), and odds ratio 2.0 for eGFR(cysC) less than 60 mL/min/1.73 m(2) (95% confidence interval, 1.03 to 3.75; P = 0.04) after adjustment for demographic factors, study site, diabetes, and smoking. The association of lower eGFR(cysC) with LVH was attenuated after further adjustment for hypertension.

LIMITATIONS

Cross-sectional rather than longitudinal design, lack of participants with more advanced kidney disease, lack of a direct measurement of glomerular filtration rate.

CONCLUSIONS

In participants without chronic kidney disease, eGFR(cysC) of 75 mL/min/1.73 m(2) or less was associated with a greater odds of LVH.

Hypertrophy and fibrosis in the cardiomyopathy of uremia--beyond coronary heart disease

Cardiac disease is the leading cause of death in uremic patients. In contrast to previous opinion, coronary events account for a relatively small proportion of cardiac deaths, the most common causes being sudden death and heart failure. Against this background the current text will discuss noncoronary cardiac pathology, specifically the pathogenesis and the morphological findings caused by (pathological) cardiac hypertrophy, cardiac interstitial fibrosis and microvascular disease.

QT interval prolongation and ventricular fibrillation in childhood end-stage renal disease

Ventricular arrhythmia is a major cause of death in end-stage renal disease (ESRD). Corrected QT (QTc) interval prolongation, which is one of the predictors of ventricular arrhythmia, may be associated with ESRD. We report an 11-year-old boy who had ESRD with marked QTc interval prolongation and developed torsade de pointes with subsequent ventricular fibrillation during the induction of anesthesia. QTc interval was normalized completely after renal transplantation.

The effectiveness of renal transplantation as a treatment for recurrent uremic cardiomyopathy

Congestive heart failure is more prevalent in patients with end-stage renal disease than in the general population. Although optimal treatment has yet to be defined, these patients are considered to be at high risk for renal transplantation. The present report of a 27-year-old man describes a full recovery from uremic cardiomyopathy following a renal transplant. Despite the patient developing recurrent cardiac dysfunction following graft failure, a second transplant was successful, which, again, resulted in complete resolution of the cardiomyopathy. Patients with recurrent uremic cardiomyopathy following failed kidney transplantation should be considered for a second kidney transplant.

Length of the QT interval: determinants and prognostic implications in a population-based prospective study of older men

OBJECTIVE

We examined potential determinants and prognostic value of the corrected QT interval (QTc).

DESIGN

A total of 4252 British men aged 60 to 79 years had a resting 12-lead electrocardiogram. Potential determinants of the QTc were assessed using multivariable regression. Men were followed up for 7 years.

RESULTS

A 1 standard deviation increase in QTc (26 milliseconds) was associated with increased all-cause mortality (hazard ratio, 1.13; 95% confidence interval, 1.05-1.22). Longer QTc was associated with increasing age, preexisting coronary heart disease, and a range of drugs. Shorter QTc was present in diabetics and smokers. Corrected QT interval was related inversely with serum potassium and calcium and positively with serum urate, sodium, and systolic blood pressure. The relation of QTc to all-cause mortality was independent of adjustment for these factors.

CONCLUSIONS

Age, preexisting coronary heart disease, certain medications and biochemical factors, and diabetes are independently associated with QTc. Corrected QT interval is an independent predictor of all-cause mortality.

Cystatin C concentration as a predictor of systolic and diastolic heart failure

BACKGROUND

Risk factors for heart failure (HF) may differ according to ejection fraction (EF). Higher cystatin C, a marker of kidney dysfunction, is associated with incident HF, but previous studies did not determine EF at diagnosis. We hypothesized that kidney dysfunction would predict diastolic HF (DHF) better than systolic HF (SHF) in the Cardiovascular Health Study.

METHODS AND RESULTS

Cystatin C was measured in 4453 participants without HF at baseline. Incident HF was categorized as DHF (EF > or = 50%) or SHF (EF < 50%). We compared the association of cystatin C with the risk for DHF and SHF, after adjustment for age, sex, race, medications, and HF risk factors. During 8 years of follow-up, 167 participants developed DHF and 206 participants developed SHF. After adjustment, sequentially higher quartiles of cystatin C were associated with risk for SHF (competing risks hazard ratios 1.0 [reference], 1.99 [95% confidence interval 1.14-3.48], 2.32 [1.32-4.07], 3.17 [1.82-5.50], P for trend < .001). The risk for DHF was apparent only at the highest cystatin C quartile (hazard ratios 1.0 [reference], 1.09 [0.62-1.89], 1.08 [0.61-1.93], and 1.83 [1.07-3.11]).

CONCLUSIONS

Cystatin C levels are linearly associated with the incidence of systolic HF, whereas only the highest concentrations of cystatin C predict diastolic HF.

QT interval prolongation, torsade de pointes and renal disease

Torsade de pointes is a form of polymorphic ventricular tachycardia occurring in a setting of prolonged QT interval on surface electrocardiogram. Several non-antiarrhythmic drugs including antibiotic and antipsychotic agents have been shown to prolong cardiac repolarization predisposing to torsade de pointes ventricular tachycardia. Blockade of the delayed rectifier (repolarising) potassium current and drug interactions with inhibitors of the cytochromes P450 (CYP)-mediated metabolism are the most common underlying mechanisms. Many antiarrhythmic drugs have been also implicated in prolonging QT interval and triggering torsades de pointes, especially during chronic therapy or in case of acute high dose toxicity. Progressive renal disease is associated from the earliest stages with increased QT interval and dispersal and with an increased risk of cardiovascular death, specifically sudden death. It has also been reported that cCorrected QT (QTc) interval prolongation and torsade de pointes are associated with end-stage renal disease (ESRD) and that they can be a cause of sudden death in ESRD. We present a case of torsade de pointes in a 82-year-old Italian woman with chronic renal failure.

Left ventricular mass is associated with ventricular repolarization heterogeneity one year after renal transplantation

Ventricular repolarization heterogeneity (VRH) is associated with the risk of arrhythmia and cardiac death. This study investigated the association between VRH and left ventricular mass (LVM) in renal transplant recipients 1 year after transplantation. Echocardiography and 5-min 12-lead electrocardiogram were recorded and GFR was estimated (eGFR) in 68 nondiabetic patients. Beat-to-beat QT interval variability algorithm was used to calculate SDNN-QT and rMSSD-QT indices of VRH. To quantify QT interval variability relative to heart rate fluctuations, QTRR index was calculated. Left ventricular hypertrophy (LVH) was present in 44 patients (65%). LVM and incidence of LVH were increased in 28 patients with eGFR <60 mL/min/1.73 m(2) compared with 40 patients with eGFR > or =60 mL/min/1.73 m(2) (248 +/- 61 g and 86% vs. 210 +/- 46 g and 50%, respectively; p < 0.01). A direct correlation was found between LVM and SDNN-QT (R = 0.47, R(2)= 0.23; p < 0.001), rMSSD-QT (R = 0.27; R(2)= 0.10; p = 0.034), and QTRR (R = 0.55; R(2)= 0.31; p < 0.001) indices. In conclusion, greater LVM is associated with increased VRH in renal transplant recipients, providing a link with the high risk of arrhythmia and cardiac death, specifically in patients with decreased graft function.

Bone and mineral guidelines for patients with chronic kidney disease: a call for revision

Recent clinical studies of mineral metabolism in patients with chronic kidney disease have helped to verify and extend the Kidney Disease Outcomes Quality Initiative practice guidelines for bone metabolism and disease that were published in 2003. In particular, investigations that examined calcium loading, vitamin D therapy, and mortality risk associated with serum calcium and phosphate in dialysis patients have been the most helpful clinically. As a consequence, there is now a growing interest to have the previous guidelines amended accordingly, which will be performed through the Kidney Disease: Improving Global Outcomes working group after a debate within the nephrology community. The new data support this call for revision in an attempt to improve survival of the dialysis patient by emphasizing the importance of intravenous vitamin D therapy and of preventing excess calcium loading. These studies also suggest avenues for future investigation into nontraditional causes and treatments of cardiovascular disease in patients with chronic kidney disease.

The Relationship Between Renal Function and Cardiac Structure, Function, and Prognosis After Myocardial Infarction

OBJECTIVES

The purpose of this study was to determine whether alterations in cardiac structure or function contribute to the increased risk associated with renal impairment after myocardial infarction (MI).

BACKGROUND

Renal impairment is associated with adverse cardiovascular outcomes after MI.

METHODS

Echocardiography was performed on 603 patients with left ventricular (LV) dysfunction, heart failure (HF), or both after MI. Patients were grouped according to their estimated glomerular filtration rate (eGFR), and measures of cardiac structure and function were related to baseline eGFR. The relationship between eGFR and cardiac structure and function and clinical outcomes of death or HF was assessed with multivariable Cox regression.

RESULTS

Ejection fraction, infarct segment length, right ventricular function, and mitral deceleration time were not influenced by renal function. Patients with reduced eGFR had smaller LV and larger left atrial (LA) volumes and higher left ventricular mass index (LVMI) and LV mass/LV volume ratio. A greater proportion of the patients with reduced eGFR had LV hypertrophy. The relationship between eGFR and the outcome of death or HF was attenuated by including baseline differences in LVMI, and both LVMI and LA volume conferred additional prognostic information in a multivariable model.

CONCLUSIONS

Renal impairment was associated with smaller LV and larger LA volumes and increased LVMI. Systolic function was similar when compared with patients with normal renal function. Thus, reduced systolic function cannot account for worse outcomes in patients with renal impairment after MI. Indirect measures of diastolic function suggest that diastolic dysfunction might be an important mediator of increased risk in this population.

The Acute Cardiac Effects of Dialysis

It is well recognized that the procedure of hemodialysis is associated with significant changes in blood pressure and systemic hemodynamics; 20-30% of treatments are complicated by intradialytic hypotension (IDH). There are now an increasing number of studies using electrocardiographic, isotopic and echocardiographic techniques that show that subclinical myocardial ischemia occurs during dialysis. This concept is supported by some studies showing that dialysis can induce acute rises in troponins and creatinine kinase MB, although this has not been found by all authors. Some of this controversy may at least in part be due to the collection of blood samples immediately postdialysis, which is likely to be too early to reliably detect dialysis-induced elevations of cardiac enzymes. Cardiovascular death is the biggest single cause of mortality in dialysis patients and of this sudden death comprises the largest proportion. As such, there is a large body of evidence examining whether dialysis is pro-arrhythmogenic. It is clear that dialysis can increase QTc interval and QT dispersion and is capable of inducing arrhythmias on Holter monitoring, likely due to the interaction of multiple factors, some of which prime for the development of arrhythmias (particularly the presence of preexisting cardiac disease), and some of which act as triggers. However, the link between these electrocardiographic alterations and sudden death is relatively poorly studied. This review summarizes the available literature regarding the acute cardiac effects of dialysis in relation to the above, and discusses how these acute changes may contribute to the genesis of uremic cardiomyopathy and longer term cardiac outcomes.

Kidney Function, Electrocardiographic Findings, and Cardiovascular Events among Older Adults

Chronic kidney disease (CKD) is associated with cardiovascular (CV) disease and mortality. It is not known whether cardiac rhythm disturbances are more prevalent among individuals with CKD or whether resting electrocardiogram findings predict future CV events in the CKD setting. Data were obtained from the Cardiovascular Health Study, a community-based study of adults aged >/=65 yr. After exclusions for prevalent heart disease, atrial fibrillation, implantable pacemaker, or antiarrhythmic medication use, 3238 participants were analyzed. CKD was defined by an estimated GFR <60 ml/min per 1.73 m(2). Outcomes were adjudicated incident heart failure (HF), incident coronary heart disease (CHD), and mortality. Participants with CKD had longer PR and corrected QT intervals compared with those without CKD; however, differences in electrocardiographic markers were explained by traditional CV risk factors and CV medication use. After adjustment for known risk factors, each 10-ms increase in the QRS interval was associated with a 15% greater risk for incident HF (95% confidence interval [CI] 1.04 to 1.27), a 13% greater risk for CHD (95% CI 1.04 to 1.24), and a 17% greater risk for mortality (95% CI 1.09, 1.25) among CKD participants. Each 5% increase in QTI was associated with a 42% (95% CI 1.23 to 1.65), 22% (95% CI 1.07 to 1.40), and 10% (95% CI 0.98 to 1.22) greater risk for HF, CHD, and mortality, respectively. Associations seemed stronger for participants with CKD; however, no significant interactions were detected. Resting electrocardiographic abnormalities are common in CKD and independently predict future clinical CV events in this setting.

Diagnostic, prognostic, and therapeutic implications of brain natriuretic peptide in dialysis and nondialysis-dependent chronic renal failure

Premature cardiovascular disease is the leading cause of morbidity and mortality in patients with end-stage renal failure. Natriuretic peptides, specifically brain natriuretic peptide, are released from the heart in response to chamber distension and thus increased in the presence of volume expansion and cardiac overload. Their physiological role is to cause vasodilatation and promote natriuresis to maintain volume homeostasis. Increasingly serum levels of brain natriuretic peptide are used to both diagnose and manage cardiovascular disorders. Furthermore, augmenting the beneficial hemodynamic actions of brain natriuretic peptide may have a therapeutic role in decompensated heart failure. However, the diagnostic role of serum brain natriuretic peptide levels in patients with advanced renal dysfunction remains to be defined. These patients have a high prevalence of left ventricular disorders, specifically left ventricular hypertrophy, which may reduce the diagnostic utility of brain natriuretic peptide. In addition, ventricular stretch may be determined by intravascular volume status rather than by cardiac dysfunction. Nonetheless, as the prognosis of patients with end-stage renal failure and co-existing heart failure is so poor, the availability of a further marker of cardiac ''distress'' may in the future become a useful diagnostic tool and in due course may become a primary goal for titration and tailoring of therapy.

Cardiac Vascular Calcification and QT Interval in ESRD Patients: Is There a Link?

We will present our experience and our preliminary data about the correlation between cardiac calcification and QT interval (and QT dispersion) in uraemia. We studied 32 haemodialysis (HD) patients (age 69 +/- 16 years, time on dialysis 32 +/- 27 months) and 12 chronic kidney disease stage 4 (CKD-4) patients (age 66 +/- 17 years, uraemia duration 38 +/- 16 months). The patients were characterized by a good mineral control, as shown by serum phosphate levels (3.6 +/- 1.3 mg/dl in CKD-4 and 4.3 +/- 1.6 mg/dl in HD patients) and Ca x P product (46 +/- 17 and 49 +/- 16 mg(2)/dl(2), respectively). The parathyroid hormone levels were higher in HD than CKD-4 patients (p < 0.0001). A TC score >400 was found to be highly prevalent in both groups. Significantly more HD patients (62.5%) showed cardiac calcification than CKD-4 patients (33%; p = 0.01). The patients were matched for TC scores higher or lower than 400. The two groups differed by gender (p < 0.05), age (p = 0.026), frequency of diabetes mellitus (p < 0.01), uraemia follow-up period (p < 0.001), low-density lipoprotein cholesterol level (p = 0.009), Ca x P product (p = 0.002), parathyroid hormone level (p < 0.0001), and corrected QT dispersion (p < 0.0001). The QT interval was higher in HD and CKD-4 patients with higher TC scores (approximately 11%), but QT interval dispersion was significantly higher in patients with TC scores >400. QT dispersion showed a linear correlation with TC scores in both groups (r = 0.899 and p < 0.0001 and r = 0.901 and p < 0.0001). Male gender, age, time (months) of uraemia, low-density lipoprotein cholesterol, albumin, calcium x phosphorus product, parathyroid hormone, and TC score are important determinants of QT dispersion. Our data show that it is possible to link dysrhythmias and cardiac calcification in uraemic patients.

Renal transplant dysfunction--importance quantified in comparison with traditional risk factors for cardiovascular disease and mortality

BACKGROUND

Renal transplant recipients (RTR) mainly die of premature cardiovascular disease. Traditional cardiovascular disease risk factors are prevalent in RTR. Additionally, non-traditional risk factors seem to contribute to the high risk. The impact of renal dysfunction was compared with traditional risk factors for cardiovascular morbidity and mortality in 1052 placebo-treated patients of the ALERT trial.

METHODS

All patients were on cyclosporine-based immunosuppressive therapy, follow-up was 5-6 years and captured endpoints included cardiac death, non-cardiovascular death, all-cause mortality, major adverse cardiac event (MACE), non-fatal myocardial infarction (MI) and stroke.

RESULTS

A calculated 84 micromol/l increase in serum creatinine was needed to double the risk for cardiac death, an increase of 104 micromol/l to double the risk for non-cardiovascular death and an increase of 92 micromol/l to double the risk for all-cause mortality. MACE risk was doubled if serum creatinine was elevated by 141 micromol/l, age was increased by 23 years, or LDL-cholesterol by 2 mmol/l. Diabetes increased the incidences of cardiac death, all-cause mortality, MACE, stroke and non-fatal MI. A serum creatinine increase of approximately 130 micromol/l, or approximately 20 years increase in age was calculated as similar in risk for cardiac death, all-cause mortality and MACE, and comparable to risk of diabetes in RTR.

CONCLUSION

An increase in serum creatinine of 80-100 micromol/l doubles the risk for cardiac death, non-cardiovascular death and all-cause mortality in RTR. An increase of 130 micromol/l in serum creatinine or approximately 20 years increase in age is comparable to risk of diabetes.

Cardiovascular risk and renal transplantation: post hoc analyses of the Assessment of Lescol in Renal Transplantation (ALERT) Study

BACKGROUND

Renal transplantation is associated with an increased risk for premature cardiovascular disease. We analyzed the data in the placebo arm of Assessment of Lescol in Renal Transplantation (ALERT) to improve our understanding of the relationship between cardiovascular risk factors and outcomes in this unique population.

METHODS

We performed Cox survival analysis for myocardial infarction, cardiac death, and noncardiac death in 1,052 patients recruited to the placebo arm of ALERT. These subjects were aged 30 to 75 years, had stable graft function at least 6 months after transplantation, had a serum total cholesterol level between 155 and 348 mg/dL (4 and 9 mmol/L), and were receiving cyclosporine-based immunosuppression.

RESULTS

The results confirm previous studies. In multivariate analysis, preexisting coronary heart disease (hazard ratio [HR], 3.69; P < 0.001), total cholesterol level (HR, 1.55 per 50 mg/dL; P = 0.0045), and prior acute rejection (HR, 2.36; P = 0.0023) were independent risk factors. Conversely, independent risk factors for cardiac death were age (HR, 1.58 per decade; P = 0.0033), diabetes (HR, 3.35; P = 0.0002), ST-T changes on the ECG (HR, 3.17; P = 0.0004), and serum creatinine level (HR, 2.65 per milligram per deciliter; P < 0.0001).

CONCLUSION

This analysis confirms that renal transplant recipients share risk factors for myocardial infarction and cardiac death with the general population. However, the pattern of risk factors and their relationship with outcomes is atypical, highlighting the unique nature of cardiovascular risk in transplant recipients.

Diagnostic potential of circulating natriuretic peptides in chronic kidney disease

BACKGROUND

Measurement of natriuretic peptides, particularly brain natriuretic peptide (BNP) is an established method for the diagnosis of cardiovascular disorders, chiefly left ventricular (LV) dysfunction. The influence of renal function on the diagnostic utility of natriuretic peptides is unclear.

METHODS

We performed a cross-sectional study of 296 patients with renal disease but no history of cardiac disease using echocardiography to assess LV mass and function. Circulating levels of atrial natriuretic peptide (ANP) and BNP were also measured.

RESULTS

The incidence of LV hypertrophy increased with progressive renal dysfunction; from 39% in patients with near-normal renal function, to 80% in renal transplant patients. There was a negative correlation between both ANP and BNP, and glomerular filtration rate (GFR) (ANP: r = -0.28, P<0.001; BNP: r = -0.40, P<0.001). Serum ANP and BNP had sensitivity and specificity for LV hypertrophy of 39.9%, 87.4% (ANP) and 61.4%, 67.6% (BNP) respectively. Sensitivity and specificity for LV dysfunction was 77.2%, 32.4% (ANP) and 71.8%, 40.0% (BNP). Significant confounders in determining serum ANP were haemoglobin, beta blockade and albumin, while serum BNP levels were significantly confounded by GFR, albumin, haemoglobin, beta blockade and age.

CONCLUSIONS

Across a spectrum of renal dysfunction, GFR is a more important determinant of serum BNP than ventricular function, and several factors are predictors of natriuretic peptide levels. In chronic kidney disease, the use of natriuretic peptides to diagnose LV hypertrophy must be interpreted in light of these other factors. The use of these peptides in renal dysfunction to diagnose LV dysfunction may be of limited value.

Cardiovascular risk in chronic renal disease and transplantation prevention and management

Cardiovascular disease (CVD) is the single best predictor of mortality in patients with chronic kidney disease and in kidney transplant recipients. These populations are considered to be at extraordinarily high risk for CVD and its complications. On the other hand, renal dysfunction should be considered as a CVD risk factor. The management of CVD in patients with chronic kidney disease is a special challenge for clinicians. In this article, major risk factors for CVD are presented, as well as diagnosis of coronary artery disease, acute coronary syndromes, its treatment modalities (pharmacological therapy and coronary revascularisation procedures), and outcomes in patients with chronic renal failure and kidney allograft recipients.