1. Aetna considers signal-averaged electrocardiography experimental and investigational because no prospective clinical studies have demonstrated the utility of this testing in improving clinical outcomes.

2. Aetna considers the Premiere Heart 3DMP Computerized EKG System experimental and investigational because the clinical value of the system in managing persons suspected of having significant coronary artery disease has not been established.

See also CPB 579 - T-Wave Alternans.

Signal-averaged electrocardiography (SAECG) is a technique involving computerized analysis of segments of a standard electrocardiogram that allows the detection of ventricular late potentials. Ventricular late potentials in patients with cardiac abnormalities, especially coronary artery disease or following an acute myocardial infarction, have been 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.

An AHCPR assessment found that 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.   However, the high negative predictive value of SAECG is largely due to the fact that the incidence of fatal arrhythmic events among post-MI patients is now below 10 percent.  The incidence of fatal arrhythmias has declined among post-MI patients, a large percentage of whom are on antithrombotic therapy, most likely following the trend of decreased mortality rate following myocardial infarction.

In 1996, an American College of Cardiology consensus statement on SAECG concluded that SAECG has “established value” in assessing the risk of development of sustained ventricular arrhythmias in patients recovering from myocardial infarction.  However, subsequently published guidelines from the American College of Cardiology on management of acute myocardial infarction (1999) stated that the usefulness of SAECG for risk assessment after myocardial infarction is less well established by evidence/opinion.  In addition, subsequently published ACC guidelines on implantable antiarrhythmia devices (1998) do not recommend SAECG for selecting patients for automated implantable cardioverter defibrillators (AICDs).

Although it has been proposed that SAECG may be used to select post myocardial infarction patients for antiarrhythmic drugs or AICD implantation, there are no prospective clinical studies demonstrating the clinical utility of SAECG in selecting patients for these therapies.  In addition, there are no prospective clinical studies proving that SAECG can be used successfully to select patients for electrophysiologic studies or Holter monitoring, or to use SAECG for risk stratification in lieu of these other tests.

Grimm et al (2003) studied arrhythmia risk stratification with regard to prophylactic implantable cardioverter-defibrillator patients with in idiopathic dilated cardiomyopathy (IDC).  These researchers concluded that reduced left ventricular ejection fraction and lack of beta-blocker use are important arrhythmia risk predictors in IDC, whereas SAECG, baroreflex sensitivity, heart rate variability, and T-wave alternans do not seem to be helpful for arrhythmia risk stratification.  Furthermore, in a review on electrocardiographic arrhythmia risk testing, Engel et al (2004) evaluated the various electrocardiographic (ECG) techniques that appear to have potential in assessment of risk for arrhythmia.  The resting ECG (premature ventricular contractions, QRS duration, damage scores, QT dispersion, and ST segment and T wave abnormalities), T-wave alternans, late potentials identified on SAECG, and heart rate variability were explored.  The authors stated that unequivocal evidence to support the widespread use of any single non-invasive technique is lacking; further research in this area is needed.

Guidelines from the European Society for Cardiology (Brignole, et al., 2004) concluded that the systematic use of SAECG in syncope is “not recommended.”

The Premier Heart digital database-driven multiphase (3DMP) electrocardiograph (EKG) System provides a computer analysis of digitalized 12-lead EKG waveforms in the frequency domain (power spectral estimate) to aid in the detection of significant coronary artery disease.  The 3DMP system was cleared by the FDA based on a 510(k) application.  Weiss, et al. (2002) reported on a cross-sectional analysis of the use of the 3DMP system in 136 patients with symptoms of potential coronary artery disease who were scheduled for angiography.  Originally, 200 patients were selected for the study, but 64 of the patients were not included in the study because of various technical problems in their 3DMP readings.

Although the 3DMP system was positive for CAD in 76 of 78 patients with greater than 60 percent narrowing by angiography, the 3DMP system also read positive in 8 of 12 patients with 40 to 60 percent narrowing.  None of the 10 patients with >0 to 40 percent narrowing read as positive by the 3DMP system, but 8 of 36 patients with 0 percent narrowing read as positive for CAD.

As a significant number (2 of 78) of patients with significant angiographic lesions were missed by the 3DMP system, it is not clear that the device is sufficiently accurate to either be used in lieu of angiography or to select patients for angiography.

There are no evidence-based guidelines from national professional organizations that address the clinical utility of 3DMP in evaluating patients suspected of having coronary artery disease.  Prospective clinical studies are necessary to demonstrate the clinical utility of the 3DMP system in managing patients suspected of having significant coronary artery disease.