The Potential of Electrocardiography for Cardiac Risk Prediction in Chronic and End-stage Kidney Disease

Sofia Skampardoni; Dimitrios Poulikakos; Marek Malik; Darren Green; Philip A. Kalra

Disclosures

Nephrol Dial Transplant. 2019;34(7):1089-1098. 

In This Article

Abstract and Introduction

Abstract

Cardiovascular mortality is very high in chronic and end-stage kidney disease (ESKD). However, risk stratification data are lacking. Sudden cardiac deaths are among the most common cardiovascular causes of death in these populations. As a result, many studies have assessed the prognostic potential of various electrocardiographic parameters in the renal population. Recent data from studies of implantable loop recordings in haemodialysis patients from five different countries have shed light on a pre-eminent bradyarrhythmic risk of mortality. Importantly, heart block addressed by permanent pacing system was detected in a proportion of patients during the prolonged recording periods. Standard electrocardiogram is inexpensive, non-invasive and easily accessible. Hence, risk prediction models using this simple investigation tool could easily translate into clinical practice. We believe that electrocardiographic assessment is currently under-valued in renal populations. For this review, we identified studies from the preceding 10 years that assessed the use of conventional and novel electrocardiographic biomarkers as risk predictors in chronic and ESKD. The review indicates that conventional electrocardiographic markers are not reliable for risk stratification in the renal populations. Novel parameters have shown promising results in smaller studies, but further validation in larger populations is required.

Introduction

Non-dialysis chronic kidney disease (CKD) is characterized by much higher cardiovascular mortality and morbidity when compared with the general population. This risk increases exponentially in end-stage kidney disease (ESKD).[1] US Renal registry data indicate that sudden death and/or fatal arrhythmia is the documented cause of death in ~26% of ESKD patients.[2]

Although atherosclerotic disease is common in CKD and ESKD, evidence indicates that it accounts for only a small proportion of cardiovascular deaths in this population.[3] Furthermore, extrapolating evidence from the general population for cardiac risk modification has proven to be of limited benefit in dialysis patients. Statin therapy for primary prevention does not reduce cardiac risk in dialysis patients[4] and coronary revascularization,[3] or use of implantable cardioverter defibrillators[5] based on the current guidelines (i.e. guidelines developed based on studies in cardiac patients), does not reduce arrhythmic mortality in CKD and ESKD patients. In the general population, most fatal arrhythmic events are triggered by underlying myocardial ischaemia, usually in the presence of coronary artery disease,[6] and are frequently tachyarrhythmias although bradyarrhythmic sudden deaths also occur. In advanced CKD and ESKD, the mechanism, timeline and specific rhythm of such events are not fully understood. Non-conventional cardiovascular risk factors such as electrolyte imbalances, volume shifts and blood pressure changes have been implicated in extremely high sudden death rates after the long interdialytic interval of the typical three session of haemodialysis (HD) a week.[7] Recent studies of prolonged implantable loop recording in five different HD cohorts have suggested that bradyarrhythmic events may be more common than ventricular arrhythmia in causing sudden cardiac deaths (SCDs).[8] Although the underlying mechanisms are far from clear, ~10% of the patients in these cohorts were noted to have heart block or other bradyarrhythmia that could be treated with permanent pacing systems, and this itself should make the case for more frequent use of standard electrocardiogram (ECG) in dialysis populations. In recent years, data from experimental and population-based studies have led to advances in our understanding of the underlying cardiovascular disease mechanisms. This led to focussing on the dynamic interplay between myocardial structural changes, vascular changes, autonomic imbalance, inflammation, and fluid and electrolyte shifts that can lead to arrhythmias.[9]

The presumed high burden of arrhythmic deaths in dialysis patients has led to a renewed interest in the evaluation of electrocardiographic parameters as potential risk predictors. The standard 12-lead ECG is an easily accessible and inexpensive bedside test. Moreover, the implementation of advanced software in most modern electrocardiographic machines means that vectorcardiographic indices can be derived with accuracy from standard 12-lead ECGs.

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