Cardiac disease in chronic uremia: pathophysiology

Mortality of dialysis patients in Qatar: A retrospective epidemiologic study

BACKGROUND

End-stage kidney disease (ESKD) patients on maintenance renal replacement therapy (RRT) have far lower life spans than those of the general population. No previous studies have been performed to assess the mortality of dialysis patients in the State of Qatar. We designed this study to assess the mortality of dialysis patients in Qatar and the impact of dialysis modality.

METHODS

All chronic ambulatory dialysis patients (both on hemodialysis (HD) and peritoneal dialysis (PD) between 2014 and 2016) were included in the study, whereas patients undergoing dialysis for less than 3 months were excluded. We reviewed patients' demographics, comorbidities, and general laboratory investigations through our electronic record system and collected and analyzed them. We identified patients who died during that period and compared them to those who survived. We performed a subanalysis for HD versus PD patients who died.

RESULTS

The total number of deceased dialysis patients was 164, with an overall crude mortality rate of 6.4%. They were significantly older than those who survived (p = 0.0001). The mortality rate was significantly higher in female than in male patients (51.2% and 38.9%, respectively) (p = 0.004) but significantly lower in PD than HD patients (1.36%, PD; 5.0%, HD; p = 0.007). It was also significantly higher in natives than in the expats (60.3% and 39.6%, respectively) (p = 0.0008); however, no significant differences were noted between deceased natives and expats in most demographic and laboratory characteristics. The most common cause of patient death was CVD (62 patients, 37.8%), followed by sepsis (44 patients, 26.8%). Diabetes, cerebrovascular accident, and dyslipidemia were more common in HD deceased patients than in PD patients (80.6%, 47%, and 59%, respectively, in HD patients vs 68.5%, 42%, and 31%, respectively, in PD patients). Albumin and potassium levels in deceased PD patients were significantly lower than in HD patients (p = 0.001).

CONCLUSION

Our study found that the high-risk population had a significant mortality, which was higher in HD than PD patients. This is the first study to look at these outcomes in Qatar. We identified multiple mortality associated factors, such as comorbid conditions and old age. We believe that improving treatment and close monitoring for comorbid conditions in the dialysis population might improve survival.

Cardiac Imaging for Coronary Heart Disease Risk Stratification in Chronic Kidney Disease

Chronic kidney disease (CKD), defined as dysfunction of the glomerular filtration apparatus, is an independent risk factor for the development of coronary artery disease (CAD). Patients with CKD are at a substantially higher risk of cardiovascular mortality compared with the age- and sex-adjusted general population with normal kidney function. The risk of CAD and mortality in patients with CKD is correlated with the degree of renal dysfunction including presence of microalbuminuria. A greater cardiovascular risk, albeit lower than for patients receiving dialysis, persists even after kidney transplantation. Congestive heart failure, commonly caused by CAD, also accounts for a significant portion of the cardiovascular-related events observed in CKD. The optimal strategy for the evaluation of CAD in patients with CKD, particularly before renal transplantation, remains a topic of contention spanning over several decades. Although the evaluation of coexisting cardiac disease in patients with CKD is desirable, severe renal dysfunction limits the use of radiographic and magnetic resonance contrast agents due to concerns regarding contrast-induced nephropathy and nephrogenic systemic sclerosis, respectively. In addition, many patients with CKD have extensive and premature (often medial) calcification disproportionate to the severity of obstructive CAD, thereby limiting the diagnostic value of computed tomography angiography. As such, echocardiography, non-contrast-enhanced magnetic resonance, nuclear myocardial perfusion, and metabolic imaging offer a variety of approaches to assess obstructive CAD and cardiomyopathy of advanced CKD without the need for nephrotoxic contrast agents.

Qt Dispersion and Signal-Averaged Electrocardiogram in Hemodialysis and Capd Patients

Objective

The aim of this study was to compare QT dispersion (QTd) and signal-averaged electrocardiogram (SA-ECG) parameters that may predict risk of malignant arrhythmias in patients on hemodialysis (HD), on continuous ambulatory peritoneal dialysis (CAPD), and in controls.

Setting

Controlled cross-sectional study in a tertiary- care setting.

Patients

28 HD (M/F 18/10; mean age 32 ± 9 years), 29 CAPD (M/F 17/12; mean age 34 ± 10 years), and 29 healthy controls (M/F 17/12; mean age 32 ± 8 years) were included.

Interventions

On ECG, minimum (QTmin) and maximum (QTmax) QT duration and their difference (QTd) were measured. In SA-ECG, duration of filtered QRS, HFLA signals less than 40 μV, and RMS voltage (40 ms) were also measured.

Results

Higher serum Ca2+ and lower K+ levels were found in CAPD compared to HD. All QT parameters were increased in HD and CAPD compared to controls. QT dispersion was significantly prolonged in HD compared to CAPD. In HD, QTd was correlated with left ventricular (LV) mass index ( r = 0.53, p = 0.004), but not in CAPD ( r = -0.09, p = 0.63). QT dispersion was significantly prolonged in patients with LV hypertrophy compared to patients without hypertrophy on HD (68 ± 18 ms vs 49 ± 18 ms, p = 0.008). In the analysis of SA-ECG, 3 of the 28 (11%) HD and 2 of the 29 (7%) CAPD patients had abnormal late potentials. Patients on HD and CAPD had significantly higher filtered-QRS duration compared to controls (105 ± 15 ms and 104 ± 12 ms vs 95 ± 5 ms, respectively, p = 0.04). Patients with LV hypertrophy had higher filtered-QRS duration compared to patients without hypertrophy (109 ± 12 ms vs 95 ± 8 ms, p < 0.001).

Conclusion

Dialysis patients had prolonged QTd and increased filtered-QRS duration in SA-ECG compared to controls. Patients on HD had longer QTd than patients on CAPD. QTd has been correlated to LV mass index in HD, but not in CAPD. This difference might be due to the effect of different dialysis modalities on electrolytes, especially the higher serum Ca2+ levels.

Assessment of the left ventricular function in patients with uremia using layer-specific 2-dimensional speckle tracking echocardiography

The aim of this research is to evaluate the longitudinal and circumferential systolic function of the left ventricle with different configurations from endocardium, midmyocardium, and epicardium, respectively, in patients with uremia using layer-specific 2-dimensional speckle tracking echocardiography (2D-STE).According to the different left ventricular (LV) configurations, 119 patients with uremia were divided into 2 groups: LV normal group (LVN group, n = 63) and LV hypertrophy group (LVH group, n = 56). In all, 66 healthy volunteers were selected as controls. High-frame rate 2-dimensional images were recorded from the apical 4-chamber view, apical 2-chamber view, parasternal LV long-axis view, and mitral annulus, papillary muscle, and apical levels of the parasternal LV short-axis view during 3 consecutive cardiac cycles. The peak systolic longitudinal strain (LS) and circumferential strain (CS) were measured in the endocardium, midmyocardium, and epicardium.In the 3 groups, the endocardium had the highest LS and CS, whereas the epicardium had the lowest LS and CS; the LS and CS of each group gradually decreased from the endocardium to the epicardium in all the 3 sections; the LS and CS of the myocardial layers were kept gradient features, namely, endocardium > midmyocardium > epicardium. The LS of the endocardium in the LVN and LVH groups was significantly lower than that in the control group (P < .05). The LS of the midmyocardium and epicardium in the LVH group were significantly lower than those in the control group (P < .05). The LS of the endocardium significantly decreased in the LVH group compared with that in the LVN group (P < .05). The CS of the endocardium and midmyocardium in the LVH group significantly decreased compared with those in the control and LVN groups (P < .05). There were no significant differences in the CS between the LVN and control groups (P > .05).In patients with uremia, the longitudinal and circumferential systolic function in 3 myocardial layers of the LVH group, and the longitudinal systolic function in endocardium of the LVN group were found significantly impaired by layer-specific 2D-STE.

Novel cardiac nuclear magnetic resonance method for noninvasive assessment of myocardial fibrosis in hemodialysis patients

Left ventricular hypertrophy and myocardial fibrosis frequently occur in patients with end-stage renal disease receiving hemodialysis therapy and are associated with poor prognosis. Native T1 mapping is a novel cardiac magnetic resonance imaging technique that measures native myocardial T1 relaxation, a surrogate of myocardial fibrosis. Here we compared global and segmental native myocardial T1 time and global longitudinal, circumferential and segmental strain, and cardiac function of 35 hemodialysis patients and 22 control individuals. The median native global T1 time was significantly higher in the hemodialysis than the control group (1270 vs. 1085 ms), with the septal regions of hemodialysis patients having significantly higher median T1 times than nonseptal regions (1293 vs. 1252 ms). The mean peak global circumferential strain and global longitudinal strain were both significantly reduced in hemodialysis patients compared with controls (-18.3 vs. -21.7 and -16.1 vs. -20.4, respectively). Systolic strain was also significantly reduced in the septum compared with the nonseptal myocardium in hemodialysis patients (-16.2 vs. -21.9) but not in control subjects. Global circumferential strain and longitudinal strain significantly correlated with global native T1 values (r = 0.41 and 0.55, respectively), and the septal native T1 significantly correlated with the septal systolic strain (r = 0.46). Thus, myocardial fibrosis may be assessed noninvasively with native T1 mapping; the interventricular septum appears to be particularly prone to the development of fibrosis in hemodialysis patients.

FGF23 from bench to bedside

There is a strong association between elevated circulating fibroblast growth factor-23 (FGF23) levels and adverse outcomes in patients with chronic kidney disease (CKD) of all stages. Initially discovered as a regulator of phosphate and vitamin D homeostasis, FGF23 has now been implicated in several pathophysiological mechanisms that may negatively impact the cardiovascular and renal systems. FGF23 is purported to have direct (off-target) effects in the myocardium, as well as canonical effects on FGF receptor/α-klotho receptor complexes in the kidney to activate the renin-angiotensin-aldosterone system, modulate soluble α-klotho levels, and increase sodium retention, to cause left ventricular hypertrophy (LVH). Conversely, FGF23 could be an innocent bystander produced in response to chronic inflammation or other processes associated with CKD that cause LVH and adverse cardiovascular outcomes. Further exploration of these complex mechanisms is needed before modulation of FGF23 can become a legitimate clinical target in CKD.

Assessment of residual alveolar bone volume in hemodialysis patients using CBCT

BACKGROUND

The study aims to assess the residual alveolar bone volume in Chinese chronic kidney disease (CKD) patients undergoing hemodialysis (HD) using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Two hundred and eight HD patients and healthy controls were enrolled to undergo CBCT examination. To evaluate residual alveolar bone volume, bone height was measured from the alveolar crest (AC) to the maxillary sinus floor or the mandibular nerve canal, whereas bone width was measured at a depth of 1.0, 3.0, and 6.0 mm apical to the AC.

RESULTS

There was no significant difference in demographics and the extent of tooth loss between HD patients and control group. Both groups showed abundant residual bone volume. However, the heights of residual alveolar bone at the upper premolars and first molar in HD patients were significantly lower than those of the control group (p < 0.05). No significant difference was observed for alveolar bone at the lower premolars and molars. The bone width showed statistical differences for HD patients' upper second molars, lower first premolars, and second molars (p < 0.05).

CONCLUSIONS

While the residual bone was sufficient for implant placement, HD patients exhibited with significantly lower residual bone height at the sites of the upper premolars and first molar and varied residual bone width depending on the location.

CLINICAL RELEVANCE

Owing to these changes, special cautions need to be taken for patients undergoing HD or with chronically impaired renal functions during implant treatment planning.

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.

Role of thyroid hormones and mir-208 in myocardial remodeling in 5/6 nephrectomized rats

BACKGROUND AND AIMS

Thyroid hormones exert important effects on heart remodeling through mir-208. The process may have a role in myocardial changes in chronic kidney disease where thyroid abnormalities are common. In this study the effect of T4 supplementation on left ventricle (LV) remodeling in 5/6 nephrectomized rats (5/6Nx) was analyzed.

METHODS

5/6Nx rats and 5/6Nx under T4 supplementation (5/6Nx + T4) were compared with control (C) and thyroidectomized (Tx) rats. After 8 weeks of follow-up, LV was analyzed for α-MHC, β-MHC, TGF-β, and mir-208 expression, hydroxyproline content, and myocardial fibrosis. Serum collagenase activity was also analyzed.

RESULTS

Heart weight increased in 5/6Nx rats compared to C, which was prevented with T4 supplementation (C, 1.5 ± 0.04; 5/6Nx, 1.8 ± 0.09; 5/6Nx + T4, 1.6 ± 0.07 g, p <0.05). The same pattern was seen for LV wall thickness, hydroxyproline content, LV fibrosis, and mRNA TGF-β expression (C, 0.47 ± 0.17; 5/6Nx, 10.55 ± 3.4; 5/6Nx + T4, 3.01 ± 0.52, p <0.01). Tx rats had reduction in heart weight, increased LV wall thickness, and fibrosis. Collagenase activity did not change in any group. mRNA expression of α-, β-MHC, and TGF-β increased in 5/6Nx in comparison to C and 5/6Nx + T4. Expression of mir-208 decreased in 5/6Nx groups, and levels were restored with T4 supplementation (4.21 ± 0.28, 3.39 ± 0.29, and 4.26 ± 0.37 RU, respectively, p <0.01).

CONCLUSIONS

Decreased plasma level of thyroid hormones or sensitivity at tissue level observed in chronic kidney disease induced by 5/6Nx has an important effect in heart remodeling processes, some of it related or mediated by mir-208 and TGF-β expression in the heart.

Aldosterone and cortisol affect the risk of sudden cardiac death in haemodialysis patients

BACKGROUND

Sudden cardiac death is common and accounts largely for the excess mortality of patients on maintenance dialysis. It is unknown whether aldosterone and cortisol increase the incidence of sudden cardiac death in dialysis patients.

METHODS AND RESULTS

We analysed data from 1255 diabetic haemodialysis patients participating in the German Diabetes and Dialysis Study (4D Study). Categories of aldosterone and cortisol were determined at baseline and patients were followed for a median of 4 years. By Cox regression analyses, hazard ratios (HRs) were determined for the effect of aldosterone, cortisol, and their combination on sudden death and other adjudicated cardiovascular outcomes. The mean age of the patients was 66 ± 8 years (54% male). Median aldosterone was <15 pg/mL (detection limit) and cortisol 16.8 µg/dL. Patients with aldosterone levels >200 pg/mL had a significantly higher risk of sudden death (HR: 1.69; 95% CI: 1.06-2.69) compared with those with an aldosterone <15 pg/mL. The combined presence of high aldosterone (>200 pg/mL) and high cortisol (>21.1 µg/dL) levels increased the risk of sudden death in striking contrast to patients with low aldosterone (<15 pg/mL) and low cortisol (<13.2 µg/dL) levels (HR: 2.86, 95% CI: 1.32-6.21). Furthermore, all-cause mortality was significantly increased in the patients with high levels of both hormones (HR: 1.62, 95% CI: 1.01-2.62).

CONCLUSIONS

The joint presence of high aldosterone and high cortisol levels is strongly associated with sudden cardiac death as well as all-cause mortality in haemodialysed type 2 diabetic patients. Whether a blockade of the mineralocorticoid receptor decreases the risk of sudden death in these patients must be examined in future trials.

Candesartan cilexetil in haemodialysis patients

OBJECTIVE

Intermittent activation of the renin-angiotensin system during dialysis may be related to the high risk of cardiovascular disease in dialysis patients. The aim of the present study was to investigate the pharmacokinetics and short-term tolerability of the angiotensin II type 1 receptor antagonist candesartan cilexetil in patients receiving chronic haemodialysis.

DESIGN

The study was a double-blind, randomised, placebo-controlled, dose-escalation study. Candesartan cilexetil was administered once daily, starting at 4mg with up-titration biweekly to 8mg and 16mg, respectively. Trough plasma concentrations of candesartan were determined before dialysis. After 2 weeks on the highest dose, plasma concentrations were obtained at frequent intervals after dose administration.

PATIENTS

Twenty patients receiving chronic haemodialysis and with adequately controlled blood pressure were included in the study. Fourteen patients were randomised to candesartan cilexetil and six to placebo.

RESULTS

Nine of the patients randomised to candesartan cilexitil reached the maximum dose of 16mg and completed the study according to protocol. Their blood pressure remained stable. Four patients discontinued active treatment due to hypotension at the lowest dose. Trough plasma concentrations of candesartan determined at the end of each study period increased linearly with dose. Following administration of candesartan cilexetil 16mg the maximum plasma concentration of candesartan was 244 +/- 54 mug/L and the area under the concentration-time curve over 24 hours, i.e. one dosing interval (AUC(tau)), was 2767 +/- 1162 mug/L . h.

CONCLUSION

Steady-state plasma concentrations of candesartan were approximately twice as high in haemodialysis patients as in subjects with normal renal function. Provided blood pressure is carefully monitored, candesartan cilexetil can be titrated from 4mg up to 16mg once daily in haemodialysis patients.

Biomarkers in hemodialysis patients

Patients with chronic kidney disease (CKD) are, compared to the general population, at higher risk of cardiovascular disease (CVD), including sudden death, coronary artery disease (CAD), congestive heart failure (HF), stroke, and peripheral artery disease. The presence of CVD is independently associated with kidney function decline. Renal insufficiency is a strong and independent predictor of mortality in patients with different CKD stages. The interplay of traditional and nontraditional risk factors is complex such that risk factor profiles are different in CKD patients. Seemingly, paradoxical associations between traditional risk factors and cardiovascular outcome complicate efforts to identify real cardiovascular etiology in these patients. Additional tools are often required to aid clinical assessment of cardiovascular risk. Recently, a number of cardiovascular biomarkers were identified as predictors of outcome in CVD. These may be used to guide early diagnosis and therapy for CVD or may predict outcome in CKD. This review focuses on the potential diagnostic and prognostic use of some important new biomarkers including brain natriuretic peptide (BNP), cardiac troponins (cTns), inflammatory markers, adhesion molecules, and asymmetric dimethylarginine (ADMA) in CKD as well as those patients with end-stage renal failure.

Increased cardiac troponin T levels are related to inflammatory markers and various indices of renal function in chronic renal disease patients

BACKGROUND/OBJECTIVES

Cardiovascular disease begins early in the course of chronic kidney disease (CKD), and the glomerular filtration rate (GFR) is an independent risk factor for it. There is little information on cardiac troponin concentrations in patients with CKD who have not commenced dialysis. Factors associated with this deleterious process are not completely understood, and we aimed to determine associated laboratory abnormalities of increased cardiac troponin T (cTnT) in patients with CKD.

METHODS

In this study, 104 patients (65 males and 39 females with mean age of 65 ± 15 years) were recruited. A detailed clinical history was recorded and routine biochemical variables and cTnT levels were measured. GFR was estimated (44.62 ± 14.38 mL/min/1.73 m(2)) using the modification of diet in renal disease study formula.

RESULTS

cTnT is correlated with blood urea (r = 0.262, p < 0.05), uric acid (r = 0.399, p < 0.001), blood phosphorus (r = 0.550, p < 0.001), triglyceride (r = 0.329, p = 0.011), C-reactive protein (CRP; r = 0.768, p < 0.001), renal resistive index (RRI; r = 0.412, p = 0.017), and GFR (r = -0.755, p = 0.011). On stepwise multiple regression analysis, increased CRP (≥12 mg/L), uric acid (≥5 mg/L), and RRI (≥0.70) were independent variables for increased cTnT status (r(2) = 0.053, p < 0.05).

CONCLUSION

Increased cTnT not only shows ongoing inflammation but also is a sensitive marker of functioning renal mass. It is strongly correlated with factors influencing the decline in renal function; thus, it can be used as a renal risk parameter.

Altered relative concentrations of high-energy phosphates in patients with uraemic cardiomyopathy measured by magnetic resonance spectroscopy

BACKGROUND

Premature sudden cardiovascular death is the commonest cause of death in end-stage renal disease (ESRD) patients and is associated with uraemic cardiomyopathy [left ventricular hypertrophy (LVH), systolic dysfunction (LVSD) or LV dilation]. High-energy phosphates (HEP), quantified using phosphorus-31 magnetic resonance spectroscopy, are reduced in patients with diabetes, heart failure and uraemia. Phosphocreatine:β adenosine triphosphate (PCr:ATP) ratio is an index of metabolic activity. We compared resting HEPs in ESRD patients and hypertensive patients (with and without LVH) who had normal renal function (LVH-only or normal myocardia). We also assessed associations of HEP levels with abnormalities of uraemic cardiomyopathy.

METHODS

Fifty-three ESRD and 30 hypertensive patients (18 with LVH, 12 with normal myocardia) underwent phosphorus magnetic resonance spectroscopy of their left ventricle. PCr:ATP ratios were calculated from (31)P-MR spectra obtained from long-axis views of the left ventricle.

RESULTS

There were no significant differences in age, LV mass, chamber sizes and ejection fraction between patient groups. PCr:ATP was significantly lower in ESRD patients compared to hypertensive patients, irrespective of the presence or absence of LVH (P = 0.01). In the ESRD group, PCr:ATP was significantly lower in patients with LVSD (P = 0.05) and LV dilation (P = 0.01). LVH was not associated with significant difference in PCr:ATP.

CONCLUSIONS

ESRD patients have lower HEP levels compared to hypertensive patients. Lower PCr:ATP ratio, indicating altered myocardial metabolic function in ESRD patients, is associated with features of uraemic cardiomyopathy.

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.

High-dose enalapril treatment reverses myocardial fibrosis in experimental uremic cardiomyopathy

AIMS

Patients with renal failure develop cardiovascular alterations which contribute to the higher rate of cardiac death. Blockade of the renin angiotensin system ameliorates the development of such changes. It is unclear, however, to what extent ACE-inhibitors can also reverse existing cardiovascular alterations. Therefore, we investigated the effect of high dose enalapril treatment on these alterations.

METHODS

Male Sprague Dawley rats underwent subtotal nephrectomy (SNX, n = 34) or sham operation (sham, n = 39). Eight weeks after surgery, rats were sacrificed or allocated to treatment with either high-dose enalapril, combination of furosemide/dihydralazine or solvent for 4 weeks. Heart and aorta were evaluated using morphometry, stereological techniques and TaqMan PCR.

RESULTS

After 8 and 12 weeks systolic blood pressure, albumin excretion, and left ventricular weight were significantly higher in untreated SNX compared to sham. Twelve weeks after SNX a significantly higher volume density of cardiac interstitial tissue (2.57±0.43% in SNX vs 1.50±0.43% in sham, p<0.05) and a significantly lower capillary length density (4532±355 mm/mm(3) in SNX vs 5023±624 mm/mm(3) in sham, p<0.05) were found. Treatment of SNX with enalapril from week 8-12 significantly improved myocardial fibrosis (1.63±0.25%, p<0.05), but not capillary reduction (3908±486 mm/mm(3)) or increased intercapillary distance. In contrast, alternative antihypertensive treatment showed no such effect. Significantly increased media thickness together with decreased vascular smooth muscles cell number and a disarray of elastic fibres were found in the aorta of SNX animals compared to sham. Both antihypertensive treatments failed to cause complete regression of these alterations.

CONCLUSIONS

The study indicates that high dose ACE-I treatment causes partial, but not complete, reversal of cardiovascular changes in SNX.

Cellular basis of uraemic cardiomyopathy: a role for erythropoietin?

The use of erythropoietin (EPO) has revolutionized the treatment of anaemia associated with many conditions including chronic kidney disease (CKD). However, little is known of the cellular impact of EPO on the uraemic heart. The discovery that the EPO receptor (EPOR) is also expressed on non-haematopoietic cells including cardiomyocytes highlights a role of EPO beyond haematopoiesis. Animal models of heart failure have shown EPO can potentially reverse cardiac remodelling and improve myocardial function. Damage to the kidney, during uraemia, results in a decreased EPO production, which may render the uraemic heart more susceptible to damage and heart failure. Here we review current data on the cellular actions of EPO in models of left ventricular hypertrophy and heart failure and highlight parallels with the uraemic heart.

Uremic cardiomyopathy and insulin resistance: a critical role for akt?

Uremic cardiomyopathy is a classic complication of chronic renal failure whose cause is unclear and treatment remains disappointing. Insulin resistance is an independent predictor of cardiovascular mortality in chronic renal failure. Underlying insulin resistance are defects in insulin signaling through the protein kinase, Akt. Akt acts as a nodal point in the control of both the metabolic and pleiotropic effects of insulin. Imbalance among these effects leads to cardiac hypertrophy, fibrosis, and apoptosis; less angiogenesis; metabolic remodeling; and altered calcium cycling, all key features of uremic cardiomyopathy. Here we consider the role of Akt in the development of uremic cardiomyopathy, drawing parallels from models of hypertrophic cardiac disease.

Gene expression profiling on global cDNA arrays gives hints concerning potential signal transduction pathways involved in cardiac fibrosis of renal failure

Cardiac remodelling with interstitial fibrosis in renal failure, which so far is only poorly understood on the molecular level, was investigated in the rat model by a global gene expression profiling analysis. Sprague–Dawley rats were subjected to subtotal nephrectomy (SNX) or sham operation (sham) and followed for 2 and 12 weeks, respectively. Heart-specific gene expression profiling, with RZPD Rat Unigene-1 cDNA arrays containing about 27 000 gene and EST sequences revealed substantial changes in gene expression in SNX compared to sham animals. Motor protein genes, growth and differentiation markers, and extracellular matrix genes were upregulated in SNX rats. Obviously, not only genes involved in cardiomyocyte hypertrophy, but also genes involved in the expansion of non-vascular interstitial tissue are activated very early in animals with renal failure. Together with earlier findings in the SNX model, the present data suggest the hypothesis that the local renin–angiotensin system (RAS) may be activated by at least two pathways: (a) via second messengers and Gproteins (short-term signalling); and (b) via motor proteins, actins and integrins (longterm signalling). The study documents that complex hybridization analysis yields reproducible and promising results of patterns of gene activation pointing to signalling pathways involved in cardiac remodelling in renal failure. The complete array data are available via http://www.rzpd.de/cgi-bin/services/exp/viewExpressionData.pl.cgi

Myocardial fibrosis and diastolic dysfunction in patients on chronic haemodialysis

BACKGROUND

Left ventricular (LV) diastolic dysfunction is linked to myocardial collagen content in many cardiac diseases. There are no data regarding such relationship in patients with end-stage renal disease (ESRD) undergoing haemodialysis.

METHODS

Twenty-five patients with ESRD undergoing haemodialysis were studied by echocardiography. LV diastolic function was investigated by Doppler echocardiography, by analysing LV filling velocities at rest and during loading manoeuvres, which represent an estimate of LV filling pressure. According to the Doppler pattern, LV filling pressure in a given patient was judged to be normal or slightly increased or to be moderately or severely increased. The presence of myocardial fibrosis was estimated by ultrasound tissue characterization with integrated backscatter, which in diastole correlates with the collagen content of the myocardium.

RESULTS

Integrated backscatter was higher in patients with moderate or severely increased than in patients with normal or slightly increased LV filling pressure (integrated backscatter: 51.0 +/- 9.8 vs 41.6 +/- 5.6%; P = 0.008). Integrated backscatter was a strong and independent determinant of diastolic dysfunction (odds ratio = 1.212; P = 0.040).

CONCLUSION

Our data support the hypothesis that, in a selected population of patients with ESRD undergoing haemodialysis, myocardial fibrosis is associated with LV diastolic myocardial properties.

Hypertension and hyperparathyroidism are associated with left ventricular hypertrophy in patients on hemodialysis

Conflicting data for association between left ventricular hypertrophy (LVH) and secondary hyperparathyroidism has been reported previously among dialysis patients. The present study was conducted to evaluate the association of hyperparathyroidism and hypertension with LVH. Charts of 130 patients on hemodialysis for at least six months were reviewed. All were subjected to M-mode echocardiography. Left ventricular mass (LVM) was calculated by Devereux's formula. LVM Index (LVMI) was calculated by dividing LVM by body surface area. Sera were analyzed for intact parathyroid hormone (iPTH). iPTH of > 32 pmol/l and a mean blood pressure (MAP) of > 107 mmHg were considered high. Patients were stratified into groups according to their MAP and iPTH. A total of (47.7%) patients were males and 68 (52.3%) were females. Their median age was 57 years. The median duration on dialysis was 26 months. Forty eight (36.9%) patients had high BP and 54 (41.5%) had high iPTH. Both high BP and high iPTH were present in 38 (29.2%) patients. Analysis of the relationship between LVM, LVMI, MAP and iPTH showed that LVM and LVMI were significantly (P < 0.001) higher in patients with concomitant high BP and high iPTH. LVMI was significantly higher in patients with high iPTH alone. Concomitant high iPTH and high MAP increase the risk of LVH in hemodialysis patients. High iPTH alone might contribute in escalating LVH. Adequate control of hypertension and hyperparathyroidism might reduce the risk of developing LVH.

The association between parathyroid hormone and mortality in dialysis patients is modified by wasting

BACKGROUND

The association between parathyroid hormone (PTH) level and mortality in dialysis patients is controversial. We hypothesized that wasting, a common condition potentially related to adynamic bone disease, modifies the association of PTH with mortality and cardiovascular events (CVE), respectively.

METHODS

We analysed data from 1255 diabetic haemodialysis patients, participating in the German Diabetes and Dialysis Study between 1998 and 2004. The patients were stratified by the presence or absence of wasting (albumin <or=3.8 versus albumin >3.8 g/dL; BMI <or=23 versus BMI >23 kg/m(2)). Using Cox regression analyses, we calculated the risks of (1) all-cause mortality and (2) CVE according to baseline PTH levels. All analyses were adjusted for age, sex, atorvastatin treatment, duration of dialysis, comorbidity, HbA1c, phosphate, calcium, blood pressure, haemoglobin and C-reactive protein.

RESULTS

Patients had a mean age of 66 +/- 8 years, and 54% were male. Among patients without wasting (albumin >3.8 g/dL, n = 586), the risks of death and CVE during 4 years of follow-up significantly increased by 23% and 20% per unit increase in logPTH. Patients in the highest PTH tertile had a 74% higher risk of death (HR(adj) 1.74, 95% CI 1.27-2.40) and a 49% higher risk of CVE (HR(adj) 1.49, 95% CI 1.05-2.11) compared to patients in the lowest PTH tertile. In contrast, no effect was found in patients with wasting. Accordingly, additional analyses in strata of BMI showed that PTH significantly impacted on death and CVE [HR(logPTH)(adj) 1.15 and 1.14, respectively] only in patients without, but not in patients with, wasting.

CONCLUSIONS

Wasting modifies the association of PTH with adverse outcomes in diabetic dialysis patients. High PTH levels are of concern in the patients without wasting, while the effect of PTH on mortality is nullified in the patients with wasting.

Cinacalcet: pharmacological and clinical aspects

The calcium sensing receptor (CaSR) is expressed in cells secreting calcium-regulating hormones, in cells involved in calcium transport and in many other tissues, with an as yet not completely defined role. In parathyroid cells, the CaSR stimulation inhibits parathyroid hormone (PTH) secretion, synthesis and parathyroid cell proliferation. Cinacalcet belongs to calcimimetic type II compounds that can interact with CaSR, increasing its affinity for calcium. Clinical studies have proved cinacalcet to be effective in reducing calcium and PTH levels in primary hyperparathyroidism and in reducing PTH, calcium and phosphate in patients with secondary hyperparathyroidism owing to chronic renal failure, with a relatively safe profile, the only reported adverse events being hypocalcaemia and gastrointestinal symptoms. However, though calcimimetics do represent a real advancement in the field of the treatment of PTH secretion disturbances, there is a need for clinical trials, which should aim to demonstrate that a better control of biochemical parameters is also matched with better clinical outcomes.

Bone and mineral disorders in pre-dialysis CKD

Disorders in calcium, phosphorus, and parathyroid hormone (PTH) are common in chronic kidney disease (CKD) and may be associated with poor outcomes including a higher rate of CKD progression and increased death risk. Although these abnormalities have been examined extensively in patients with CKD stage 5 who are receiving chronic maintenance dialysis, they have not been studied to the same extent at earlier stages of CKD, in spite of the much larger numbers of patients in the early CKD population. We summarize the available literature on outcomes associated with bone and mineral disorders in patients with CKD not yet receiving maintenance dialysis. We have reviewed novel data linking fibroblast growth factor 23 (FGF-23) to phosphorus and vitamin D homeostasis. More rapid CKD progression is linked to hyperphosphatemia and its associated hyperparathyroidism and vitamin D deficiency. Hence, hyperphosphatemia may play a central role in the diverse disorders characterizing CKD. We provide a brief overview of the available treatment recommendations for bone and mineral disorders, with an emphasis on areas needing further research.

Cause-specific mortality of dialysis patients after coronary revascularization: why don't dialysis patients have better survival after coronary intervention?

INTRODUCTION

The risk of death after coronary revascularization is markedly higher for dialysis patients than for the general population and the cause is inadequately explained. We analyzed cause-specific mortality of dialysis patients after coronary revascularization.

METHODS

This was a retrospective analysis of dialysis patients hospitalized for first surgical coronary revascularization after renal replacement therapy initiation from 1 January 1999 to 31 December 2002. Patients were identified from the US Renal Data System database (n = 1,516,251) by the International Classification of Diseases, Ninth Edition, Clinical Modification code for coronary artery bypass (CAB) surgery (36.1x). Endpoints were deaths due to all causes, all cardiac causes, cardiac arrest or arrhythmia, myocardial infarction, infection and other causes. Cause-specific mortality information was obtained from Centers for Medicare & Medicaid Services End-Stage Renal Disease Death Notification form (CMS 2746-U3).

RESULTS

For CAB patients (n = 5830), the all-cause mortality rate was 290 per 1000 patient-years and the rate for arrhythmically mediated deaths was 76 per 1000 patient-years. The largest cause of attributable mortality is cardiac arrest or arrhythmia, accounting for approximately one-fourth of all-cause mortality.

CONCLUSIONS

The risk of arrhythmically mediated death may contribute to poor long-term outcomes after coronary revascularization in dialysis patients. A treatment strategy employing coronary revascularization and other interventions to reduce the sudden cardiac death risk might improve long-term survival.

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.

A single session of haemodialysis improves left ventricular synchronicity in patients with end-stage renal disease: a pilot tissue synchronization imaging study

BACKGROUND

Mechanical left ventricular (LV) dyssynchrony impairs cardiac function in patients with heart failure and LV hypertrophy (LVH) and may be a factor contributing to the high incidence of cardiac deaths in patients with end-stage renal disease (ESRD). Objectives. To evaluate the possible presence of LV dyssynchrony in ESRD patients, and acute effect of haemodialysis (HD) on LV synchronicity using a tailored echocardiographic modality, tissue synchronization imaging (TSI).

METHODS

In 13 clinically stable ESRD patients (7 men; 65 +/- 10 years) with LVH, echocardiography data were acquired before and after a single HD session for subsequent off-line TSI analysis enabling the retrieval of regional intraventricular systolic delay data. Six basal and six midventricular LV segments were evaluated. Dyssynchrony was defined as a regional difference in time to peak systolic velocity >105 ms.

RESULTS

Before HD, all patients had at least one dyssynchronous LV segment. The percentage of delayed segments correlated positively to LV end-diastolic diameter (r = 0.68, P < 0.05). HD induced a substantial decrease in the percentage of delayed segments from 36 +/- 25% to 19 +/- 14% (P < 0.01), reduced average maximal mechanical systolic LV delay from 300 +/- 89 to 225 +/- 116 ms (P < 0.05) and completely normalized LV synchronicity in three patients (23%).

CONCLUSIONS

LV dyssynchrony appears to be present frequently in ESRD patients with LVH. The severity of LV dyssynchrony correlates with LV end-diastolic diameter and decreases after a single session of HD suggesting a mechanistic relevance of volume overload and possibly other toxins accumulating in HD patients.

Long-term (>3 Years) outcome and predictors of clinical events after insertion of sirolimus-eluting stent in one or more native coronary arteries (from the Israeli arm of the e-Cypher registry)

The aim of this study was to evaluate long-term (3.4 years) outcomes and predictors of clinical events in patients treated with sirolimus-eluting stents in the Israeli arm of the e-Cypher registry. From July 2002 to October 2003, 488 patients from 8 medical centers in Israel were enrolled in the e-Cypher registry. Nineteen patients with interventions in venous grafts were excluded from the final analysis. Long-term follow-up was completed for 98% of the remaining patients. There were 29 cases (6.3%) of death (3.9% cardiac and 2.4% noncardiac deaths). According to the broad academic research consortium definition of stent thrombosis, there were 19 cases (4%) of stent thrombosis (incidence density 0.9 cases/100 patient-years). There were 46 cases (9.9%) of target lesion revascularization and 76 cases (16.3%) of major adverse cardiac events (combination of death, myocardial infarction, and target lesion revascularization). Independent predictors of stent thrombosis were renal failure (hazard ratio 9.6, 95% confidence interval 1.9 to 47), stent length (hazard ratio 1.1, 95% confidence interval 1 to 1.2), and the off-label use of sirolimus-eluting stents (hazard ratio 5.3, 95% confidence interval 1.2 to 24). In conclusion, during >3 years of follow-up, stent thrombosis, major adverse cardiac events, and target lesion revascularization continued at constant rates over time. Clinical parameters such as renal failure and procedural parameters such as off-label use and stent length were independent predictors of stent thrombosis.

Secondary hyperparathyroidism is associated with higher mortality in men with moderate to severe chronic kidney disease

Secondary hyperparathyroidism is associated with mortality in patients undergoing maintenance dialysis treatment. We studied 515 male US veterans with chronic kidney disease, who were not yet on dialysis, to see what outcomes were associated with secondary hyperparathyroidism in this population. Relationships between intact parathyroid hormone levels and all-cause mortality along with the composite of mortality or incidence of dialysis were measured in unadjusted and adjusted Cox models for case-mix and laboratory variables. Elevated parathyroid hormone levels above the upper limit compared to the lower limit of the normal range were significantly associated with mortality after adjustments. Higher intact parathyroid hormone levels in the upper limit of normal were significantly associated with higher mortality overall and showed similar trends in subgroups of patients with stage 3 and stage 4-5 chronic kidney disease and with higher and lower serum calcium and phosphorus levels. Similar associations were found with the composite outcome of mortality or dialysis. Our study shows that secondary hyperparathyroidism is independently associated with higher mortality in patients with chronic kidney disease but not yet on dialysis.

Management of ischemic heart disease in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) and ischemic heart disease (IHD) have strikingly high mortality rates. In the general population, there has been a reduction in the mortality and morbidity rates for IHD through the implementation of effective risk-factor-reduction programs and better interventions for patients with established IHD. No such trend has been observed in patients with end-stage kidney disease. This review article addresses the following topics: (i) epidemiology, pathogenesis, clinical CKD patients with IHD; (ii) diagnostic modalities for IHD and their limitation in CKD patients; (iii) medical treatment options and revascularization strategies for these high-risk patients; and (iv) optimal cardiovascular risk management. Generally, in CKD patients with IHD an aggressive approach to IHD is warranted, a low threshold for diagnostic testing should be employed, and awaiting a clinical trial targeting these patients they should be considered for all proven strategies to improve outcomes.

Paricalcitol aggravates perivascular fibrosis in rats with renal insufficiency and low calcitriol

Cardiovascular complications are a major problem in chronic renal failure. We examined the effects of plasma calcium, phosphate, parathyroid hormone (PTH), and calcitriol on cardiac morphology in 5/6 nephrectomized rats. Fifteen weeks after nephrectomy rats were given a control diet, high-calcium or -phosphorus diet, or given paricalcitol treatment for 12 weeks. Sham-operated rats were on a control diet. Blood pressure, plasma phosphate, and PTH were increased, while the creatinine clearance was reduced in remnant kidney rats. Phosphate and PTH were further elevated by the high-phosphate diet but suppressed by the high-calcium diet, while paricalcitol reduced PTH without influencing phosphate or calcium. The high-calcium diet increased, while the high-phosphate diet reduced plasma calcium. Plasma calcitriol was significantly reduced in other remnant kidney groups, but further decreased after paricalcitol. Cardiac perivascular fibrosis and connective tissue growth factor were significantly increased in the remnant kidney groups, and further increased in paricalcitol-treated rats. Hence, regardless of the calcium, phosphate, or PTH levels, cardiac perivascular fibrosis and connective tissue growth factor increase in rats with renal insufficiency in association with low calcitriol. Possible explanations are that aggravated perivascular fibrosis after paricalcitol in renal insufficiency may be due to further suppression of calcitriol, or to a direct effect of the vitamin D analog.

Anemia, renal transplantation, and the anemia paradox

Anemia is prevalent in renal transplant recipients (RTRs), as it is in all chronic kidney disease (CKD) populations. Mild anemia occurs in up to 40% of RTRs, and more severe anemia (110 g/L) occurs in about 9% to 22% of patients. As in CKD, impaired graft (renal) function is a major predictor of anemia identified in nearly all studies, suggesting a major role for erythropoietin deficiency. Chronic inflammation, malnutrition, iron deficiency, and medications (angiotensin converting enzyme inhibitors, angiotensin receptor blockers, mycophenolate, azathioprine, and sirolimus) are contributory factors seen in some, but not all, studies. Although pathophysiologic and observational data strongly support a causal association between low hemoglobin levels and cardiovascular outcomes in RTRs, no randomized controlled trial to date has been able to show a clear benefit of anemia treatment on cardiovascular outcomes or mortality in either RTR or other CKD populations. This important paradox has led some investigators to question the causal nature of the association between anemia and heart disease. Resolution of this paradox, at least for patients with stage 2/3 CKD, will depend on the outcome of randomized controlled trials currently in progress. Similar trials sorely are needed in renal transplant populations. In the interim, current opinion favors treating persistent anemia in RTRs to achieve targets similar to those recommended for dialysis and CKD patients.

Cinacalcet HCl: A Novel Treatment for Secondary Hyperparathyroidism Caused by Chronic Kidney Disease

Secondary hyperparathyroidism (SHPT) develops as a result of impaired calcium homeostasis when the failing kidneys disturb the complicated interactions between parathyroid hormone (PTH), calcium, phosphorus, and vitamin D. Twelve years ago, the calcium-sensing receptor (CaR) of the parathyroid gland was first cloned and identified as the principal regulator of PTH secretion. The activation of the CaR by small changes in extracellular calcium (ec(Ca2+)) regulates PTH, calcitonin secretion, urinary calcium excretion, and ultimately, bone turnover. The CaR became an ideal target for the development of calcimimetics, which are able to amplify its sensitivity to ec(Ca2+) suppressing PTH secretion. Cinacalcet HCl, a first-in-class calcimimetic, approved in both the United States and the European Union, offers a new therapeutic approach to the treatment of SHPT. The efficacy of cinacalcet HCl in treating SHPT in dialysis patients (n = 1,136) was studied in three similarly designed phase III clinical trials comparing patients receiving standard SHPT therapy plus cinacalcet HCl or plus placebo. Cinacalcet HCl, dosed from 30 to 180 mg/day, significantly reduced PTH while simultaneously lowering calcium, phosphorus, and calcium-phosphorus product in each of the three studies. Respective to the National Kidney Foundation-Kidney Disease Outcomes and Quality Initiative (NKF-K/DOQI) recommended targets for bone and mineral metabolism, 41% of cinacalcet HCl-treated patients achieved both PTH and calcium-phosphorus product targets, compared with only 6% in the placebo group. Results from 2 recent phase IIIb studies (TARGET and CONTROL) conducted in the United States also showed that cinacalcet HCl can significantly reduce or maintain reduction in PTH while simultaneously lowering calcium, phosphorus, and calcium-phosphorus product. In addition, patients taking vitamin D at baseline of these 2 trials were able to see significant mean reductions in vitamin D dose. Further assessment of cinacalcet HCl trial data has shown some important effects in SHPT patient clinical outcomes. A combined post-hoc analysis of clinical events using data from 4 (n = 1,184) cinacalcet HCl phase II and III studies suggests that treatment with cinacalcet HCl has a beneficial effect on relative risks of parathyroidectomy, fracture, and hospitalization for cardiovascular complications. Nausea and vomiting occurred more often in patients taking cinacalcet HCl than in those taking a placebo. There were also transient episodes of hypocalcemia in 5% of cinacalcet HCl patients versus 1% of placebo patients. However, these episodes were rarely associated with symptoms. The development of calcimimetics has already changed the treatment of SHPT in renal patients. Its effectiveness on the control of PTH secretion, along with simultaneous reductions in calcium, phosphorus, and calcium-phosphorus product, give this agent an advantage over traditional therapies in all levels of severity of SHPT.

New Therapies for Uremic Secondary Hyperparathyroidism

Secondary hyperparathyroidism (SHPT) is a common and serious complication of chronic kidney disease (CKD). It affects more than 300,000 end-stage renal disease patients treated by dialysis and probably more than 3 million patients with CKD worldwide. For a long time, traditional therapies for SHPT had consisted of correcting the hypocalcemia using calcium salts and vitamin D derivatives, preventing the hyperphosphatemia by calcium- or aluminum-containing intestinal phosphate binders, and recently by using no metal-containing intestinal phosphate binders; however, these therapies are limited by the occurrence of hypercalcemia, hyperphosphatemia, and the lack of specificity and long-term efficacy. Moreover, surgical parathyroidectomy (PTX), which remains the gold standard therapy, is not exempt from risk. PTX exposes patients to anesthesia risks, presurgical and postsurgical complications, and in many cases a permanent state of hypoparathyroidism. Thus, the medical treatment of SHPT became an ideal target for the development of new therapies and strategies. The purpose of this article is to provide an overview of these new therapies, including vitamin D analogs, intestinal phosphate binders, calcimimetics, parathyroidectomies, tyrosine kinase inhibitors, azydothymidine, anticalcineurins, N-terminal truncated parathyroid hormone fragments, bisphosphonates, calcitonin, osteoprotegerin, and others. The use of these new therapies alone or in combination may help to optimize the future treatment of SHPT in CKD patients.

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

Chronic renal failure is characterized by an increased risk for cardiovascular morbidity and mortality, including acute myocardial infarction (AMI). AMI is associated with poor long-term survival in dialysis patients; the 2-year survival rate of 25% has remained unchanged over the past 2 decades. Although underuse of appropriate therapies likely contributes to adverse outcomes, recent data suggest that dialysis patients with AMI are more likely to have clinical presentations atypical for acute coronary syndrome. The risk for cardiac arrest and in-hospital death are increased in dialysis patients with AMI compared with a nondialysis cohort. The phenomenon of increased AMI mortality in patients with chronic kidney disease is not restricted to end-stage renal disease because there is a gradient of mortality risk related to decreased renal function. Sudden cardiac death is the single largest cause of mortality in dialysis patients. Dialysis patients are vulnerable to sudden cardiac death, and myocardial ischemia likely plays a major role. Nevertheless, after percutaneous and surgical coronary revascularization dialysis patients remain at high risk for sudden cardiac death, implying that other factors besides myocardial ischemia are important. A randomized trial testing the efficacy of implantable cardioverter-defibrillators for the prevention of sudden cardiac death in dialysis patients is warranted.

Incidence, predictors, and associated outcomes of atrial fibrillation after kidney transplantation

The risk for and predictors of atrial fibrillation (AF) after kidney transplantation are not well described. Registry data that were collected by the United States Renal Data System were used to investigate retrospectively new-onset AF among adult first renal allograft recipients and transplant candidates who received a transplant or were wait-listed in 1995 to 2001 with Medicare as the primary payer. AF events were ascertained from billing records, and participants were followed until loss of Medicare coverage or December 31, 2001. Cox hazards analysis was used to identify independent correlates of posttransplantation AF (adjusted hazard ratio [AHR]; 95% confidence interval [CI]) and to examine AF as an outcomes predictor. Among 31,136 eligible transplant recipients, the cumulative incidence of new-onset AF was 3.6% (95% CI 3.4 to 3.8%) and 7.3% (95% CI 7.0 to 7.6%) at 12 and 36 mo and declined below the demographics-adjusted cumulative incidence on the waiting list by approximately 17 mo. Risk factors for posttransplantation AF included older recipient age, male gender, white race, renal failure from hypertension, and coronary artery disease. Extended pretransplantation dialysis duration, posttransplantation diabetes, and graft failure were identified as potentially modifiable correlates of AF. In separate analyses, AF independently predicted death (AHR 3.2; 95% CI 2.9 to 3.6) and death-censored graft loss (AHR 1.9; 95% CI 1.6 to 2.3). As the population of renal transplant recipients grows older, the incidence and prevalence of AF among these patients will likely increase. Appropriate risk stratification may identify transplant recipients who are in need of close monitoring for and management of this adverse cardiovascular event.

Nocturnal hemodialysis is associated with restoration of impaired endothelial progenitor cell biology in end-stage renal disease

Cardiovascular disease is the principal cause of death in end-stage renal disease (ESRD) patients. Endothelial progenitor cells (EPCs) play a critical role in vascular repair, and improving EPC biology represents a novel therapeutic target. Three groups of age- and gender-matched patients were studied: 1) 10 healthy control, 2) 12 conventional hemodialysis (CHD) patients, and 3) 10 nocturnal hemodialysis (NHD) patients. EPC number and migratory function were assessed. Left ventricular mass index (LVMI) was derived, and correlations between EPC biology, uremic clearance, and LVMI were made. Compared with controls, EPC number and function were markedly impaired in CHD patients [(3.48 ± 1.2 vs. 0.86 ± 0.20%/50,000 cells, P < 0.05) and (18.8 ± 2.64 vs. 3.75 ± 0.34 cells/high-power field, P < 0.05), respectively]. In contrast, EPC number and function were normal in NHD patients [(3.48 ± 1.17 vs. 3.83 ± 0.77%/50,000 cells) and (18.8 ± 2.6 vs. 22.2 ± 2.4 cells/high-power field), respectively]. Among ESRD patients, EPC number and function inversely correlated with predialysis urea concentration ( r = −0.40; r = −0.57), LVMI ( r = −0.41; −0.46) and systolic BP ( r = −0.58; r = −0.44). We demonstrate that NHD is associated with restoration of abnormal EPC biology in ESRD. Given the increasing importance of EPCs in the repair and restoration of cardiovascular function, these data have important clinical implications for vascular risk in ESRD patients.

The role of secondary hyperparathyroidism in left ventricular hypertrophy of patients under chronic hemodialysis

End-stage renal disease (ESRD) patients frequently develop structural cardiac abnormalities, particularly left ventricular hypertrophy (LVH). The mechanisms involved in these processes are not completely understood. In the present study, we evaluated a possible association between parathyroid hormone (PTH) levels and left ventricular mass (LVM) in patients with ESRD. Stable uremic patients on intermittent hemodialysis treatment were evaluated by standard two-dimensional echocardiography and their sera were analyzed for intact PTH. Forty-one patients (mean age 45 years, range 18 to 61 years), 61% males, who had been on hemodialysis for 3 to 186 months, were evaluated. Patients were stratified into 3 groups according to serum PTH: low levels (< 100 pg/ml; group I = 10 patients), intermediate levels (100 to 280 pg/ml; group II = 10 patients) and high levels (> 280 pg/ml; group III = 21 patients). A positive statistically significant association between LVM index and PTH was identified (r = 0.34; P = 0.03, Pearson's correlation coefficient) in the sample as a whole. In subgroup analyses, we did not observe significant associations in the low and intermediate PTH groups; nevertheless, PTH and LVM index were correlated in patients with high PTH levels (r = 0.62; P = 0.003). LVM index was also inversely associated with hemoglobin (r = -0.34; P = 0.03). In multivariate analysis, after adjustment for age, hemoglobin, body mass index, and blood pressure, the only independent predictor of LVM index was PTH level. Therefore, PTH is an independent predictor of LVH in patients undergoing chronic hemodialysis. Secondary hyperparathyroidism may contribute to the elevated cardiovascular morbidity associated with LVH in ESRD.

Calcium, Phosphorus, Parathyroid Hormone, and Cardiovascular Disease in Hemodialysis Patients: The USRDS Waves 1, 3, and 4 Study

Animal studies suggest that calcium-phosphorus homeostatic abnormalities cause cardiovascular disease in uremia; few observational studies in humans have explored this. Associations in the retrospective United States Renal Data System Waves 1, 3, and 4 Study of 14,829 patients who were on hemodialysis on December 31, 1993, were examined. Mean age and duration of renal replacement therapy were 60.0 and 3.2 yr, respectively; 40.7% had diabetes. Quintiles (Q(1) to Q(5)) of (albumin-adjusted) calcium were </=8.7, 8.8 to 9.2, 9.3 to 9.6, 9.7 to 10.2, and >10.2 mg/dl; phosphorus, </=4.4, 4.5 to 5.3, 5.4 to 6.3, 6.4 to 7.5, and >7.5 mg/dl; calcium-phosphorus product, </=40.9, 41.0 to 50.1, 50.2 to 59.2, 59.3 to 71.0, and >71.0 mg(2)/dl(2); and parathyroid hormone (PTH), </=37, 38 to 99, 100 to 210, 211 to 480, and >480 pg/ml. Higher calcium levels were associated with fatal or nonfatal cardiovascular events (adjusted hazards ratio, 1.08 for Q(5), versus Q(1)) and all-cause mortality (Q(2), 1.07; Q(4), 1.11; Q(5), 1.14). Phosphorus levels were associated with cardiovascular events (Q(2), 1.06; Q(3), 1.13; Q(4), 1.14; Q(5), 1.25) and mortality (Q(4), 1.10; Q(5), 1.19), calcium-phosphorus product was associated with cardiovascular events (Q(3), 1.09; Q(4), 1.14; Q(5), 1.24) and mortality (Q(4), 1.09; Q(5), 1.19), and PTH levels were associated with cardiovascular events (Q(5), 1.12) and mortality (Q(5), 1.17). Despite limitations (including retrospective design; noncurrent study era; and lack of serial calcium, phosphorus, and PTH measurements), this study suggests that disorders of calcium homeostasis are associated with fatal and nonfatal cardiovascular events and all-cause mortality in hemodialysis patients.

Significance of Acute versus Chronic Troponin T Elevation in Dialysis Patients

INTRODUCTION

Cardiac troponin T (cTnT) is often elevated in hemodialysis (HD) patients without acute coronary syndrome (ACS). The aim was to assess the predictive value for mortality of pre-dialysis cTnT in asymptomatic patients. If patients became symptomatic during follow-up, cTnT was followed to assess its diagnostic value for ACS.

METHODS

Forty-nine asymptomatic HD patients were included: 30 patients with a history of cardiovascular disease (CV+) and 19 without (CV-). In 11 patients cTnT, myoglobin and creatine kinase (CK) were measured before and during HD. During ACS, cTnT was followed until recovery. A cTnT of > or =0.03 mug/l was considered elevated. Follow-up was 2 years.

RESULTS

cTnT was elevated in 82% (40/49). More CV+ patients had an elevated cTnT (28/30) than CV- patients (12/19; p = 0.02). There was no change in cTnT, myoglobin and CK during HD. During ACS, cTnT increased above baseline, and tended to return to baseline after recovery. Mortality was 33% (16/49). Patients with elevated cTnT had a higher mortality rate (16/40) than patients with negative cTnT (0/9; p = 0.02).

CONCLUSIONS

Elevated cTnT levels in asymptomatic HD patients are not caused by acute myocardial injury or by HD itself. They may be related to chronic myocardial damage and decreased clearance, and are of prognostic value. During ACS, however, a cTnT rise above the individual baseline is diagnostic of acute myocardial injury.