Opportunities for improvement in the cardiovascular care of patients with end-stage renal disease

A Call to Action to Develop Integrated Curricula in Cardiorenal Medicine

With the adoption of the new definition and classification of cardiorenal syndrome (CRS) and its relevant subtypes, much attention has been placed on elucidating the mechanisms of heart and kidney interactions. Of great interest are the pathophysiological pathways by which acute heart failure may result in acute kidney injury (AKI; type 1), chronic heart failure accelerating the progression of chronic kidney disease (CKD; type 2), AKI provoking cardiac events (type 3), and CKD increasing the risk and severity of cardiovascular disease (type 4). A remarkable interest has also been placed on the acute and chronic systemic conditions, such as sepsis and diabetes, which simultaneously affect heart and kidney function (type 5). Furthermore, the physiology of acute and chronic heart-kidney cross talk is drawing attention to hemodynamics (fluids, pressures, flows, resistances, perfusion), physiochemical (electrolytes, pH, and toxins), and biological (inflammation, immune system activation, neurohormonal signals) processes. Common clinical scenarios call for recognition, knowledge, and skill in managing CRS. There is a clear need for medical and surgical specialists that are well versed in the pathophysiology and the clinical manifestations that arise in the setting of CRS. With this editorial, we are making a call to action to stimulate universities, medical schools, and teaching hospitals to create a core curriculum for cardiorenal medicine to better equip the physicians of the future for these common, serious, and frequently fatal syndromes.

Arrhythmia and Sudden Death in Hemodialysis Patients: Protocol and Baseline Characteristics of the Monitoring in Dialysis Study

BACKGROUND

Dialysis patients have high rates of cardiovascular morbidity and mortality, but data on arrhythmia burden, arrhythmia type, arrhythmia triggers, and the identity of terminal arrhythmias have historically been limited by an inability to monitor heart rhythm for prolonged periods.

OBJECTIVES

To investigate arrhythmia and its association with sudden death in dialysis-dependent ESRD, describe the potential for implantable devices to advance study of dialysis physiology, review the ethical implications of using implantable devices in clinical studies, and report on the protocol and baseline results of the Monitoring in Dialysis Study (MiD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this multicenter, interventional-observational, prospective cohort study, we placed implantable loop recorders in patients undergoing long-term hemodialysis. The proportion of patients experiencing clinically significant arrhythmias was the primary endpoint. For 6 months, we captured detailed data on the primary endpoint, symptomatic arrhythmias, other electrocardiographic variables, dialysis prescription, electrolytes, dialysis-related variables, and vital signs. We collected additional electrocardiographic data for up to 1 year.

RESULTS

Overall, 66 patients underwent implantation in sites in the United States and India. Diabetes was present in 63.6% of patients, 12.1% were age ≥70 years, 69.7% were men, and 53.0% were black. Primary and secondary endpoint data are expected in 2016.

CONCLUSIONS

Cardiac arrhythmia is an important contributor to cardiovascular morbidity and mortality in dialysis patients, but available technology has previously limited the ability to estimate its true burden and triggers and to define terminal rhythms in sudden death. Use of implantable technology in observational studies raises complex issues but may greatly expand understanding of dialysis physiology. The use of implantable loop recorders in MiD is among the first examples of such a trial, and the results are expected to provide novel insights into the nature of arrhythmia in hemodialysis patients.

Coronary Artery Disease

Coronary heart disease is the most common cause of death in the general population and in patients with ESRD. The principles of cardiovascular risk assessment and management apply to both populations. Advances in noninvasive coronary artery imaging have improved early detection of subclinical disease. The goals of medical management of coronary disease are to modify the natural history of disease and to improve the symptoms of angina. Coronary revascularization poses a different risk and benefit equation in the ESRD population. In stable ESRD with multivessel coronary artery disease, coronary bypass surgery, despite the upfront risks of stroke, myocardial infarction, and chest wound infection, seems to be a favored approach. In patients with ESRD and acute coronary syndromes, percutaneous coronary intervention on the target vessel has been associated with the most favorable outcomes. This article explores the clinical issues with respect to coronary artery disease in patients with ESRD.

Effectiveness of the implantable cardioverter defibrillator in blacks versus whites (from MADIT-II)

The aim of this study was to examine the effectiveness of implantable cardioverter-defibrillator (ICD) therapy in whites and blacks who were enrolled in the Multicenter Automatic Defibrillator Implantation Trial-II (MADIT-II). The study population involved 1,232 subjects, with 1,073 white patients (87%) and 102 black patients (8%). Univariate analyses revealed a significant reduction in mortality in white patients treated with ICD therapy (p <0.02), but not in black patients (p = 0.96). White patients had a significant reduction of sudden cardiac death (p <0.01), but no benefit was evident in black patients (p = 0.62). Adjusting for relevant covariates, the ICD therapy/conventional therapy hazard ratios for total mortality were favorable in whites (0.75, 95% confidence interval [CI] 0.55 to 1.02), but not in blacks (1.25, 95% CI 0.42 to 3.60); the hazard ratios for sudden cardiac death were significantly (p = 0.04) lower in whites (0.29, 95% CI 0.17 to 0.49) than in blacks (1.71, 95% CI 0.33 to 8.84). Interaction analyses revealed a pattern of progressive improvement in ICD efficacy in whites as the end point became more specific for arrhythmic death, with exactly the reverse for blacks. In conclusion, ICD therapy in MADIT-II was associated with a reduction in total mortality, cardiac death, and sudden cardiac death in whites but not in blacks.

Renal Function, Congestive Heart Failure, and Amino-Terminal Pro-Brain Natriuretic Peptide Measurement

The relationship between renal insufficiency and amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels remains unclear. We examined this relationship in the context of patients who presented to the emergency department of an urban tertiary care medical center with dyspnea. Even in the presence of renal insufficiency, NT-proBNP remained a valuable tool for the diagnosis of acute congestive heart failure and it provides important prognostic information.

OBJECTIVES

We sought to examine the interaction between renal function and amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels.

BACKGROUND

The effects of renal insufficiency on NT-proBNP among patients with and without acute congestive heart failure (CHF) are controversial. We examined the effects of kidney disease on NT-proBNP-based CHF diagnosis and prognosis.

METHODS

A total of 599 dyspneic patients with glomerular filtration rates (GFRs) as low as 14.8 ml/min were analyzed. We used multivariate logistic regression to examine covariates associated with NT-proBNP results and linear regression analysis to analyze associations between NT-proBNP and GFR. Receiver-operating characteristic analysis determined the sensitivity and specificity of NT-proBNP for CHF diagnosis. We also assessed 60-day mortality rates as a function of NT-proBNP concentration.

RESULTS

Glomerular filtration rates ranged from 15 ml/min/1.73 m2 to 252 ml/min/1.73 m2. Renal insufficiency was associated with risk factors for CHF, and patients with renal insufficiency were more likely to have CHF (all p < 0.003). Worse renal function was accompanied by cardiac structural and functional abnormalities on echocardiography. We found that NT-proBNP and GFR were inversely and independently related (p < 0.001) and that NT-proBNP values of > 450 pg/ml for patients ages <50 years and >900 pg/ml for patients > or =50 years had a sensitivity of 85% and a specificity of 88% for diagnosing acute CHF among subjects with GFR > or =60 ml/min/1.73 m2. Using a cut point of 1,200 pg/ml for subjects with GFR <60 ml/min/1.73 m2, we found sensitivity and specificity to be 89% and 72%, respectively. We found that NT-proBNP was the strongest overall independent risk factor for 60-day mortality (hazard ratio 1.57; 95% confidence interval 1.2 to 2.0; p = 0.0004) and remained so even in those with GFR <60 ml/min/1.73 m2 (hazard ratio 1.61; 95% confidence interval 1.14 to 2.26; p = 0.006).

CONCLUSIONS

The use of NT-proBNP testing is valuable for the evaluation of the dyspneic patient with suspected CHF, irrespective of renal function.

Evaluation and treatment of coronary artery disease in patients with end-stage renal disease

Evaluation and treatment of coronary artery disease in patients with end-stage renal disease. Patients with end-stage renal disease (ESRD) are at increased risk of death from coronary artery disease (CAD). The metabolic milieu that results from renal dysfunction appears to accelerate the atherosclerotic process by decades in patients with ESRD. The extremely high prevalence of atherosclerosis in patients with ESRD mandates risk factor identification and treatment. Traditionally, CAD in this patient population has been treated conservatively. Analysis of large databases has highlighted the scope and complexity of this problem; nonetheless, there is a paucity of randomized, controlled trials of CAD in patients with ESRD. In this paper the following issues related to evaluation and treatment of patients with chronic kidney disease are addressed: (1) optimal CAD risk management; (2) evaluation for CAD in patients with ESRD, including the identification of coronary calcification; (3) treatment of CAD with medical therapy and revascularization; (4) relative merits of percutaneous coronary intervention versus bypass surgery. In general, an aggressive approach to medical management of CAD is warranted, even in the setting of subclinical CAD. A low threshold for diagnostic testing should be employed in patients with ESRD. When significant CAD is identified, ESRD patients appear to benefit more from revascularization compared to conservative medical management. Thus, if clinically reasonable, patients with ESRD and CAD should be managed aggressively to improve survival and reduce the incidence of future cardiac events.