Prepared by: Ann A. Graham, C.R.N.A., M.P.H., and Harry Handelsman, D.O.

Health Technology Assessment:

Number 11

U.S. Department of Health and Human Services Public Health Service Agency for Health Care Policy and Research Rockville, Maryland

May 1998

AHCPR Pub. No. 98-0020

View the Medline Citation and Related Citations using PubMed

Signal-averaged electrocardiography (SAECG) is a technique involving computerized analysis of segments of a standard surface electrocardiogram. It is used for detecting small electrical impulses, termed ventricular late potentials, that follow the QRS segment. They are embedded in the electrocardiogram but ordinarily obscured by skeletal muscle activity and other extraneous sources of "noise" encountered in recording a standard electrocardiogram. Ventricular late potentials in patients with cardiac abnormalities, especially coronary artery disease or following an acute myocardial infarction, are associated with an increased risk of ventricular tachyarrhythmias and sudden cardiac death. Proponents of SAECG claim that it can obviate the need for invasive techniques commonly used to identify high-risk patients for interventions that treat or prevent ventricular tachyarrhythmia and sudden death.

No randomized clinical trials evaluating SAECG have been completed; data from an ongoing National Institutes of Health-sponsored clinical trial are expected to be available in 3-4 years. The current data on SAECG show relatively consistent high negative predictive values, poor positive predictive values, and variable sensitivity and specificity when the technique is used on patients with cardiomyopathy or following a myocardial infarction. The available evidence also indicates that combining SAECG with other tests of cardiac function is superior to using any single test for risk. The utility of SAECG alone as an indicator of risk remains to be proven. SAECG combined with other standard tests of risk has been demonstrated to have clinical utility in patients following an acute myocardial infarction. Other patient populations have not been conclusively shown to benefit from its use.

The Center for Practice and Technology Assessment (CPTA) evaluates the risks, benefits, and clinical effectiveness of new or established medical technologies. In most instances, assessments address technologies that are being reviewed for purposes of coverage by federally funded health programs.

The CPTA assessment process includes a comprehensive review of the medical literature and emphasizes broad and open participation from within and outside the Federal Government. A range of expert advice is obtained by widely publicizing the plans for conducting the assessment through publication of an announcement in the Federal Register and solicitation of input from Federal agencies, medical specialty societies, insurers, and manufacturers. The involvement of these experts helps ensure inclusion of the experienced and varying viewpoints needed to round out the data derived from individual scientific studies in the medical literature.

The CPTA staff analyzed and synthesized data and information received from experts and the scientific literature. The results are reported in this assessment. Each assessment represents a detailed analysis of the risks, clinical effectiveness, and uses of new or unestablished medical technologies. If an assessment has been prepared to form the basis for a coverage decision by a federally financed health care program, it serves as the Public Health Service's recommendation to that program and is disseminated widely.

The CPTA is one component of the Agency for Health Care Policy and Research (AHCPR), Public Health Service, Department of Health and Human Services.

Douglas B. Kamerow, M.D., M.P.H., Director, Center for Practice and Technology Assessment
John M. Eisenberg, M.D., Administrator, Agency for Health Care Policy and Research

Questions regarding this assessment should be directed to:

Center for Practice and Technology Assessment

Agency for Health Care Policy and Research

6010 Executive Boulevard, Room 316

Rockville, MD 20852

Telephone: (301) 594-4026

Acc:: Accuracy

ART:: Arrhythmia research technology

BBB:: Bundle branch block

CAD:: Coronary artery disease

CAST:: Cardiac arrhythmia suppression trials

CFR:: Case fatality rate

CHF:: Congestive heart failure

CI:: Confidence interval

dQRS:: Duration of the filtered QRS complex >106 ms

ECG:: Electrocardiogram

FD:: Frequency domain

FDA:: Food and Drug Administration

HCFA:: Health Care Financing Administration

IDC:: Idiopathic dilated cardiomyopathy

LAS:: Low amplitude signal

LVEF:: Left ventricular ejection fraction

LVH:: Left ventricular hypertrophy

MeSH:: Medical subject heading

MI:: Myocardial infarction

MUGA:: Multigated acquisition

NPV:: Negative predictive value

NS:: Not stated

NSR:: Normal sinus rhythm

NYHA:: New York Heart Association

PES:: Programmed electrical stimulation

PPV:: Positive predictive value

RMS:: Root mean square voltage during the last 40 ms of the QRS complex <25 µV

RNV:: Radionuclide ventriculography

SAECG:: Signal-averaged electrocardiography

SD:: Sudden death

1SD:: One standard deviation

Se:: Sensitivity

Sp:: Specificity

STA:: Spectral turbulence analysis

TD:: Time domain

VAT:: Ventricular activation time

VF:: Ventricular fibrillation

VLP:: Ventricular late potentials

VT:: Ventricular tachyarrhythmia