Coronary artery disease in patients with chronic kidney disease – By Dr Yasir Parviz, Consultant Interventional Cardiologist, Canadian Specialist Hospita. The incidence and prevalence of end-stage renal disease (ESRD) are rising in the United Arab Emirates (UAE).
The UAE population is living longer, with increasing aging population and surge in the incidence of chronic diseases such as diabetes mellitus (DM) and hypertension (HTN) the trend of Chronic Kidney Disease (CKD) is increasing in UAE. The prevalence of ESRD in a recent study from Dubai has shown 152 patients per million populations per year. Approximately over 2,000 CKD patients are undergoing dialysis in the country and this number increases by 10 to 15 percent every year.
Cardiovascular diseases are the leading causes of death in patients with CKD. Patients with CKD have chronic progressive disease process and many of these patients need renal replacement therapy (RRT)or renal transplantation. Despite the fact that they have numerous comorbidities the main concern and cause of morbidity and mortality are cardiovascular disorders. Hence it is the need of the hour that cardiovascular disorders are diagnosed, timely and appropriately to help guide the right decisions in the management of these complex group of patients.
Coronary Artery Disease is more Prevalent in CKD patients:
Patients with CKD have high likely hood of CAD. These patients are complex and have multiple other comorbidities, like hypertension, diabetes mellitus, dyslipidemia, obesity, and tobacco use, all independently associated with increasing risk of CAD. There is very high incidence of CAD in patients going for dialysis, even ranging up to 38%, with a relative risk of 5- to 20-fold that of the general population.
The disease process is different in CKD patients:
The cardiovascular disease process is different in CKD patients in comparison to general population. They have more aggressive and severe pattern of disease. It is important to understand that dialysis does not prevent the disease process or progression of CKD but transplantation has been shown to prevent the damages caused by the chemicals associated with chronic kidney disease. Hence there is an incentive that these complex patients should have an early assessment so that we can diagnose these cases early and refer for the transplantation to minimize the long-term consequences of the disease process.
Management of CAD in CKD patients is challenging:
There are a number of challenges in the management of these patients. It is well observed that many of the treatment strategies are less effective in these patients. Commonly used tablets to lower cholesterol, like statins and medications like angiotensin-converting enzyme (ACE) inhibitors and aspirin may have diminished clinical benefit in ESRD. The atherosclerotic disease process in these patients is complex and coronary plaque morphology shows extensive calcification. Even in when young patients with CKD are screened for the atherosclerotic coronary artery disease, a disproportionate incidence of high calcium scores is detected with the probability of coronary artery calcification increasing with longer duration of dialysis. The clinical presentation of these patients is different, and more patients are presenting with acute coronary syndrome in comparison to angina in patients without the renal disease.
When to Assess the CAD in CKD?
Many sets of guidelines aim to guide cardiovascular evaluation in renal transplantation candidates, but there is no universal consensus on an optimal approach. The 2014 American College of Cardiology (ACC) and American Heart Association (AHA) guidelines have given some suggestions in this regard.
The difficult decision in the management of these patients when and how to evaluate these patients. One of the important aspect that can help direct the decision-making process is the effort capacity or simply how much exercise patient can perform. Patients who can do moderate exercise with the functional capacity of moderate exercise (defined as ≥4 metabolic equivalents(METS), and who are asymptomatic and undergoing noncardiac surgery do not need a routine testing. We should investigate and evaluate patients who have poor functional capacity (<4(METS) or unknown functional status. These decisions are not simple and need expert evaluation.
What is a high-risk patient group:
The common risks to look for these patients are diabetes mellitus, prior cardiovascular disease, >1 year on dialysis, left ventricular hypertrophy (LVH), age >60 years, smoking, hypertension, and dyslipidemia. Any patients with CKD and these risk factors should be evaluated for CAD.
How Often Should Patients be evaluated?
- Annual evaluation for CAD is recommended for patients who are diabetic and awaiting renal transplantation.
- In high-risk patients without diabetes mellitus on the transplantation waitlist (≥2traditional risk factors, known the history of CAD, peripheral vascular disease, and LV ejection fraction [LVEF] ≤40%), evaluation for CAD every 24 months is re
- Patients on hemodialysis with an LVEF ≤40% or those with new symptoms of concern regarding ischemic heart disease are recommended to be evaluated continuously for CAD.
- Repeated evaluation is recommended on an annual basis in patients at high risk, with re-evaluation every 3 years for low-risk patients
Our strategy for evaluation of CAD in patients with ESRD:
Patients with CKD who attend to our clinic are assessed for cardiovascular disease according to a set protocol.
- Clinic consultation with a detailed careful clinical history and baseline ECG in all patients.
- Echocardiography to assess ventricular dimensions and function. This allows us to look for the pumping action and assessment of valves. We can detect any possible regional wall motion abnormalities by this simple test.
- Dobutamine Stress Echocardiogram. Patients with risk factors and multiple comorbidities are assessed with dobutamine stress echocardiogram for possible ischemic heart disease.
- A negative dobutamine stress test has high negative predictive value.
- It is important to note that patients with multiple risk factors for CAD (≥3 risk factors: diabetes mellitus, prior cardiovascular disease, >1 year on dialysis, LVH, peripheral arterial disease, age >60 years, smoking, hypertension, dyslipidemia) should be considered for further imaging or cardiac catheterization despite a negative stress test in some instances.
When to consider Coronary Angiography and Revascularization:
Coronary angiography is usually reserved for patients with evidence of ischemia on non-invasive imaging to determine their need for preoperative revascularization. It is to be emphasized that coronary angiography in renal transplantation candidates at high risk of CAD despite normal stress tests, should be considered. This is based on the limitations of non-invasive tests. It is important to identify prognostic ally important CAD that may require revascularization prior to transplantation.
In patients with ESRD other clues for the atherosclerotic disease should be considered. particularly peripheral arterial disease, may help identify patients with advanced coronary atherosclerosis.
The peripheral vascular disease is highly associated with CAD and it is a reasonable approach to have an evaluation of coronary artery disease in patients with peripheral arterial disease despite negative stress tests. Another group of patients where we should evaluate for coronary artery disease is patients who have cardiac autonomic dysfunction, autonomic neuropathy, and retinopathy.
One of the important consideration to be aware is patients with diabetes mellitus. In these patients when they have normal stress tests may represent a particularly high-risk group that should be considered for coronary angiography, given their high pre-test probability for CAD, as myocardial perfusion imaging has a high false-negative rate in this population.
One of the unfortunate aspects is that despite the fact that these patients are high risk for coronary artery disease these patients are less likely to get treatment strategies offered in comparison to other patients with normal renal function, as there are concerns of contrast-induced nephropathy and requirement of dialysis. Another unfortunate aspect is that even when these patients are presenting as an acute heart attack and there is a need for immediate revascularisation. These patients are less likely to get revascularized in comparison to other patients with normal kidney function.
These patients can be better managed by a collaborative work between various healthcare professionals. The decision to pursue revascularization (CABG or PCI) or to treat medically should be made after a multidisciplinary discussion among interventional cardiologists, nephrologists, and cardiothoracic surgeons and should be individualized to each patient, given the current lack of evidence to guide the treatment strategies.