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ECG-based Signal Analysis Technologies

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While chest pain is a common symptom of patients presenting to clinics and emergency wards, only about six percent of patients presenting to the emergency room with acute chest pain are ultimately diagnosed with myocardial infarction. Identification of which patients with chest pain are experiencing myocardial ischemia or infarction is critical, since a delay in diagnosis can impede the application of effective therapies, such as thrombolytic agents or percutaneous coronary intervention (PCI). Tests that identify patients with significant coronary artery disease (CAD) serve as a means of facilitating aggressive implementation of secondary preventive strategies. Thus, accurate diagnostic tests and protocols are imperative in order to properly triage patients presenting with chest pain.

In patients where CAD is suspected – either because of the presence of risk factors for CAD or because of symptoms that may represent manifestations of CAD (e.g., chest pain) – the standard electrocardiogram (ECG) is one of the most commonly performed tests. The ECG is nearly universally available, noninvasive, easy to perform, relatively inexpensive, and can usually be completed in less than 10 minutes. However, a resting ECG has limited sensitivity for detecting CAD.

New devices that seek to improve ECG capabilities have been proposed – specifically, devices that are potentially capable of detecting significant CAD or myocardial ischemia. An enhanced ECG-based test might demonstrate greater positive or negative predictive values, thereby limiting the harms associated with delays in treatment, or providing the diagnostic information necessary to avoid invasive diagnostic or therapeutic interventions.

The Coverage and Analysis Group at the Centers for Medicare and Medicaid Services (CMS) requested this report from The Technology Assessment Program (TAP) at the Agency for Healthcare Research and Quality (AHRQ). AHRQ assigned this report to the Duke Evidence-based Practice Center (Contract No. HHSA 290-2007-10066I). The purpose of the technology assessment is to summarize the available clinical and scientific evidence on ECG-based signal analysis technologies for evaluating patients with suspected CAD. Some ECG-based technologies have been used for other purposes (e.g., detection of malignant arrhythmias), but these are not the focus of the current report. Rather, this report will concentrate on commercially available ECG-based signal analysis technologies to inform AHRQ and CMS about the utility of these emerging technologies for diagnosing CAD.

We synthesized the existing literature on these technologies in response to the following key questions:

Key Question 1:
  1. What devices and methods for ECG-based signal analysis are being used or are proposed to be used for diagnosis of CAD? What is the FDA status of these devices?
  2. What are considered the “gold standard” tests for the diagnosis of CAD and what are their strengths and limitations?
Key Question 2:
  1. What is the evidence for inter-rater, intra-rater, intra-patient, and intra-device variability?
  2. What is the evidence for diagnostic test performance compared to the reference standard used in the study? What factors (confounders) affected test sensitivity and specificity?
  3. What is the evidence that ECG-based signal analysis technologies impact diagnostic decisionmaking?
  4. What is the evidence that ECG-based signal analysis technologies impact patient outcomes?
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