NKF KDOQI GUIDELINES
Section I. Guidelines on evaluation and management of cardiovascular diseases
The assessment and treatment of both risk factors and end organs are essential in the management of cardiovascular diseases. The first section will deal with the end organs and will focus on cardiac, cerebrovascular and peripheral vascular diseases. Cardiac diseases have justifiably received the most attention because they are by far the most common cause of cardiovascular deaths in dialysis patients. Cerebrovascular diseases and peripheral vascular diseases, however, also lead to substantial morbidity and mortality and have often been overlooked by practitioners and clinical researchers.
The workgroup has faced dilemma in the scope and depth of the coverage of end organ diseases. There has been only one small randomized trial that demonstrated beneficial effects of specific cardioprotective drugs (namely, carvedilol) published in dialysis patients. Therefore, most guidelines described in this section are referred from published guidelines in the general population. Nonetheless, there are unusual features in the dialysis patients that the practitioners need to be aware of. For example, the pathophysiology and rate of progression of cardiac valvular calcification appear to be different from those in the general population. Surveillance and treatment strategies should take these caveats into consideration. On the other hand, the implant of tissue valves is proscribed in the existing ACC/AHA guidelines. More recent and stronger evidence, however, suggest that tissue valves are associated with equivalent outcomes in dialysis patients. These similarities, not only differences, between dialysis patients and the general population also need to be emphasized.
The section on end organ diseases is written for not only the nephrologists, but also the general practitioners, cardiologists, vascular surgeons and other practitioners.
Guideline 2: Coronary Artery Disease
Ischemic heart disease (IHD) due to atherosclerotic CAD is common in dialysis patients. While its evaluation and treatment are important components of the ongoing care of dialysis patients, there are special considerations for both the evaluation and treatment in dialysis patients due to the issues of preservation of kidney function, vascular access, and bleeding tendencies.
2.1 The evaluation of CAD in dialysis patients depends on individual patient status. (C)
2.1a If the patient is on the kidney transplant waitlist and is diabetic (and initial evaluation is negative for CAD), then evaluation for CAD every 12 months is recommended.
2.1b If the patient is on the transplant waitlist but is not diabetic and is classified as “high risk,” then evaluation for CAD every 24 months is recommended.*
2.1c If the patient is on the transplant waitlist and is classified as not high risk, then evaluation for CAD every 36 months is recommended.*
2.1d If the patient is on the transplant waitlist with known CAD (and not revascularized), evaluation for CAD should be performed every 12 months.
2.1e If the patient is on the transplant waitlist and has a history of PTCA or coronary stent, evaluation for CAD should be performed every 12 months.
2.1f If the patient has “complete” coronary revascularization (i.e., all ischemic coronary vascular beds are bypassed), the first re-evaluation for CAD should be performed 3 years after coronary artery bypass (CAB) surgery, then every 12 months thereafter.
2.1g If the patient has “incomplete” coronary revascularization after CAB surgery (i.e., not all ischemic coronary beds are revascularized), then evaluation for CAD should be performed annually.
2.1h If there is a change in symptoms related to IHD or clinical status (e.g., recurrent hypotension, CHF unresponsive to dry weight changes, or inability to achieve dry weight because of hypotension), evaluation for CAD is recommended.
2.1i Dialysis patients with significant reduction in LV systolic function (EF<40%) should be evaluated for CAD.
2.1j Evaluation for heart disease should occur at initiation of dialysis and include a baseline electrocardiogram (ECG) and echocardiogram (see Cardiomyopathy guideline for echocardiography after dialysis initiation). Both of these tests provide information pertinent to, but not restricted to, CAD evaluation. Annual ECGs are recommended after dialysis initiation.
2.2 In patients fulfilling 2.1.a-2.1.i above, CAD evaluation should also include exercise or pharmacological stress echocardiographic or nuclear imaging tests. “Automatic” CAD evaluation with stress imaging is currently not recommended for all dialysis patients (i.e., patients not fulfilling 2.1.a-2.1.i). Stress imaging is appropriate (at the discretion of the patient’s physician) in selected high-risk dialysis patients for risk stratification even in patients who are not renal transplant candidates. (C)
2.3 Patients who are candidates for coronary interventions and have stress tests that are positive for ischemia should be referred for consideration of angiographic assessment. (C)
2.4 Special considerations in dialysis patients regarding CAD evaluation include the following: (C)
2.4a To minimize the risk of potential volume overload from the performance of angiographic studies, iso-osmolar radiocontrast media (e.g., iodixanol) should be used.
2.4b Some dialysis patients have residual renal function; there are no data on the value of “nephroprotective” strategies to reduce the potential risk of contrast nephropathy in these patients. The use of N-acetylcysteine (and iodixanol) is appropriate in dialysis patients with residual renal function, as both may offer benefit without known harm. Sodium bicarbonate and hydration are not routinely recommended, as intravascular volume expansion may pose risk to dialysis patients with increased cardiac filling pressures.
2.5 In patients undergoing invasive coronary procedures, it is important to avoid internal jugular sites and to preserve brachial and radial arteries for future dialysis catheter and arteriovenous fistula creation, respectively. (C)
2.6 Patients undergoing planned invasive procedures for evaluation or treatment of CAD should be assessed for hemorrhagic risk and presence of anemia, as anticoagulants and/or antiplatelet agents may be administered adjunctively for percutaneous coronary intervention. (C)
At least a third of incident dialysis patients have a history of CAD.54 In some patients, the development of left ventricular (LV) dysfunction or clinically evident CHF may be a reflection of underlying IHD. Evaluation for CAD should be considered even in dialysis patients who are not candidates for kidney transplantation, since they have high event rates for CAD, early hazard of acute myocardial infarction (MI) after initiation of chronic dialysis, and high mortality rate following acute MI. The purposes of using stress imaging modalities for CAD evaluation are risk stratification (i.e., prediction of likelihood of future events related to CAD), detection of obstructive CAD, and assessment of myocardial ischemic burden after coronary revascularization and/or medical therapy.
The optimal modality is strongly dependent on individual institutional expertise. Exercise ECG is not recommended because of poor exercise tolerance in general, and high prevalence of left ventricular hypertrophy (LVH) in dialysis patients, although published data have suggested a lower accuracy for CAD detection in dialysis patients using stress nuclear or echocardiographic imaging techniques, compared to the general population.55
Stress echocardiography can be performed in different ways. Similar to exercise ECG, exercise echocardiography is, in general, unsuitable for the majority of dialysis patients due to noncardiac exercise limitations. Echocardiography, in conjunction with stress by dobutamine, is a standard method. However, it should be cautioned that this method may be associated with approximately 2%-4% risk of transient atrial fibrillation in dialysis patients, compared to only 0.5% in the general population.56 Stress echocardiography can also be performed in conjunction with a vasodilator, such as adenosine or dipyridamole. The accuracy of this method in dialysis patients is poorly defined. The combination of dobutamine and a vasodilator has also been advocated for stress echocardiography, but there are no published data on this technique in the dialysis population. An advantage of echocardiography is that prestress imaging can provide additional information on LV ejection fraction and dimensions, valvular disease, pulmonary artery pressure, and volume status, as well as associated pericardial disease (e.g., pericardial effusion). (Weak)
The same techniques of stress can be applied to nuclear scintigraphy. Stress by exercise poses the same problem as exercise ECG and exercise echocardiography because of the limited noncardiac exercise tolerance in dialysis patients. Stress by adenosine and dipyridamole in conjunction with nuclear scintigraphy is a standard method recommended by the American College of Cardiology (ACC)/American Heart Association (AHA) guideline on imaging. Data on dobutamine-induced stress scintigraphy in dialysis patients are very limited. Combined stress using exercise and a vasodilator produced promising results in a single-center study of dialysis patients,57 but it has not been well examined in diabetic dialysis patients (only 14% of Dahan’s study cohort had diabetic CKD). For the purpose of risk stratification, the published data suggest that the accuracy of dobutamine echocardiography and vasodilator-induced stress nuclear scintigraphy are comparable in kidney transplant candidates. A meta-analysis that grouped both techniques together found that stress imaging was predictive of future cardiac death and MI in kidney transplant candidates.58(Weak)
For the purpose of detecting obstructive CAD in dialysis patients, the available data suggest that vasodilator-induced stress nuclear scintigraphy is less sensitive than dobutamine echocardiography. These data are predominantly derived from diabetic dialysis patients who were being evaluated for kidney transplantation, as these patients have been the focus of clinical studies on noninvasive CAD screening. This distinction may be important in monitoring patients for the detection of occult re-stenosis after percutaneous coronary intervention.
Ultrafast cardiothoracic (CT) scan or electron-beam computerized tomography (EBCT) can detect calcification of the coronary arteries. Limited data suggest that, while EBCT has a potential role in risk stratification in dialysis patients, the physiological consequences of coronary calcification cannot be assessed by EBCT. The correlation between coronary calcification and luminal diameter in dialysis patients is less certain than in the general population, since vascular calcification in this population is often the result of medial calcification rather than atherosclerosis. At the present time, EBCT (or other ultrafast CT) is not recommended for the diagnosis of CAD in dialysis patients. Experience with cardiac magnetic resonance imaging (MRI) in dialysis patients is very limited and the technique is not widely available. (Weak)
* High-risk (more than 20% per 10 years cardiovascular event rate risk) according to Framingham data includes those with two or more “traditional” risk factors, a known history of coronary disease, LV ejection fraction ≤40%, or PVD. 53
|© 2005 National Kidney Foundation, Inc.|