Elsevier

Journal of Electrocardiology

Volume 48, Issue 2, March–April 2015, Pages 249-259
Journal of Electrocardiology

Smartphone ECG for evaluation of STEMI: Results of the ST LEUIS Pilot Study

https://doi.org/10.1016/j.jelectrocard.2014.11.005Get rights and content

Highlights

  • Smartphone based ECG was compared to 12-lead ECG for 6 STEMI protocol activations.

  • Excellent concordance between smartphone and 12-lead ECG was noted on all subjects.

  • A single lead ground on either arm appeared to be adequate for acutely evaluating ischemia.

Abstract

Background

12-lead ECG is a critical component of initial evaluation of cardiac ischemia, but has traditionally been limited to large, dedicated equipment in medical care environments. Smartphones provide a potential alternative platform for the extension of ECG to new care settings and to improve timeliness of care.

Objective

To gain experience with smartphone electrocardiography prior to designing a larger multicenter study evaluating standard 12-lead ECG compared to smartphone ECG.

Methods

6 patients for whom the hospital STEMI protocol was activated were evaluated with traditional 12-lead ECG followed immediately by a smartphone ECG using right (VnR) and left (VnL) limb leads for precordial grounding. The AliveCor™ Heart Monitor was utilized for this study. All tracings were taken prior to catheterization or immediately after revascularization while still in the catheterization laboratory.

Results

The smartphone ECG had excellent correlation with the gold standard 12-lead ECG in all patients. Four out of six tracings were judged to meet STEMI criteria on both modalities as determined by three experienced cardiologists, and in the remaining two, consensus indicated a non-STEMI ECG diagnosis. No significant difference was noted between VnR and VnL.

Conclusions

Smartphone based electrocardiography is a promising, developing technology intended to increase availability and speed of electrocardiographic evaluation. This study confirmed the potential of a smartphone ECG for evaluation of acute ischemia and the feasibility of studying this technology further to define the diagnostic accuracy, limitations and appropriate use of this new technology.

Introduction

Annually, one in six deaths is due to cardiovascular disease. The American Heart Association has reported that 405,309 Americans died of cardiovascular disease (CVD) in 2008, and that annually an estimated 785,000 Americans will experience a first time coronary event, 470,000 will suffer a recurrent event, and 195,000 will have a silent first myocardial infarction[1].

Urgent revascularization is indicated in patients with ST-elevation myocardial infarction (STEMI) which is diagnosed largely on electrocardiographic criteria [2]. The majority of STEMI deaths occur within the first 1–2 hours [3]. Many barriers have been identified preventing early recognition of STEMI including lack of the patient's ability to identify that they are experiencing an MI, misattributing symptoms of STEMI to some other disease, fearing embarrassment of false alarm, not fitting a “stereotype” for heart attack, and lack of recognition by bystanders of a STEMI event [3], [4].

Given that earlier treatment of STEMI reduces mortality and morbidity, it is important to increase the speed of diagnosing a STEMI event. As ECG is the method for diagnosing STEMI and is also the most simple and accessible diagnostic modality, it is possible that by extending the availability of reliable ECGs to a high-risk outpatient population, delays to early recognition and subsequent treatment could be reduced and more prompt lifesaving revascularization achieved.

Smartphones provide a possible platform for the extension of the ECG as they have become common across world, including poorer nations. A report on a 2012 survey by the Nielsen group of US mobile consumers estimates that over half of US mobile consumers use a smartphone or smart device [5]. Smart devices do not have voice capability but are otherwise similar to smartphones with comparable hardware and software. Differences exist among operating systems and hardware specifications, but a standard set of features including a touch screen, Internet connectivity and the ability to run 3rd party applications have become ubiquitous.

With the development of smartphones, independent software developers have created applications or “apps” for multiple uses. One such app works in tandem with a phone case with embedded sensors and provides a single channel lead for accurate rate and rhythm assessment [6], [7]. This device has been shown capable of distinguishing between normal sinus rhythm and atrial fibrillation when used by a trained medical professional. The device has been validated against 12-lead ECGs in a small number of patients for accurately identifying atrial fibrillation with sensitivities from 87% to 100%, specificities from 90% to 97%, and total accuracies from 94% to 97%. The ECG readings included independent blinded assessments by three different cardiologists as well as an automated algorithm analysis [8]. More recently, the device has been shown reliable in assessing QTC intervals compared to standard 12-lead ECG [9].

While this device has been shown to provide a single channel lead reading that is diagnostic for normal sinus rhythm and atrial fibrillation, it has not been validated in its ability to provide readings during an acute MI, including time sensitive STEMI events, for accurate assessment and diagnosis at point of care or even patient-applied application.

Following the success of single lead smartphone based rhythm evaluation, interest has developed in more comprehensive electrocardiographic evaluation using smartphones which can assess ischemic ST-T wave changes. A preliminary study was recently published using the original single lead device attached to typical 12-lead ECG leads and then compared to a standard 12-lead reading. A non-acute patient population was studied and the authors noted good concordance between the two modalities [10]. At present, a test device has been created with two wire leads, designed to be used with traditional ECG stickers and connect wirelessly with a smart device. It differs from a 12-lead ECG in that the tracings are taken serially rather than simultaneously, it uses computer averaging to give a single representative tracing rather than raw voltage data, and it uses a single extremity lead for grounding of the precordial leads instead of an average. How these differences affect its ability to diagnosis STEMI and non-STEMI has not previously been determined.

The primary objective of this study was to assess the operational feasibility of using a smartphone to obtain “12-lead equivalent” ECG recordings in patients suspected to have acute MI, with particular focus on STEMI. Our intent was to use results from this pilot study to design a larger multi-center study, the objective of which is to determine if the smartphone ECG is an acceptable substitute for a standard ECG in the identification of STEMI.

Specific goals of this pilot study included: to obtain simultaneous standard 12-lead ECG and the smartphone “12-lead equivalent” ECG recordings on patients for whom the STEMI protocol was activated; to determine the operational feasibility of obtaining these simultaneous recordings; to make preliminary assessment of diagnostic accuracy; to make recommendations for the conduct of the planned multi-center study that will determine if the smartphone ECG is an acceptable replacement for a standard ECG in the identification of STEMI.

By validating the smartphone ECGs capacity to accurately assess the presence or absence of STEMI or non-STEMI compared to gold standard 12-lead ECG, we may increase the accessibility of electrocardiography and hasten the diagnosis and treatment of the life threatening events.

Section snippets

Materials and methods

This study was designed as a single center, prospective, non-randomized, open study, with a single-patient clinical design (i.e., the patients serve as their own control). Target enrollment was 5 patients and 6 patients were eventually enrolled over 27 days. Inclusion criteria included age ≥ 18 years, ability of patient or legally-acceptable representative to provide written informed consent prior to study procedure, chest pain evaluated in the emergency department, and activation of the STEMI

Results

The study enrolled six patients for whom the STEMI protocol was activated (Table 1). All 6 were white males with ages between 52 and 85 years. Expedited transfer to the catheterization laboratory led to only one ECG being obtained in the emergency department and all others being performed in the laboratory immediately post revascularization. All tracings obtained were felt to be of adequate technical quality for interpretation. Smartphone tracings and paired 12-lead ECGs are shown in Fig. 2,

Discussion

This study importantly demonstrates that the smartphone ECG is capable of identifying an ST-segment myocardial infarction using a technology platform that is now readily available. The significance of this lies in its ability to extend electrocardiographic evaluation into new use case scenarios, including personalized use by the owner or point-of-care, out-of-hospital first medical contact. These and other important scenarios include settings where a standard 12-lead ECG is not immediately

Conclusions

The AliveCor™ Heart Monitor, a smartphone device-based ECG system was found to generate “12-lead equivalent” ECGs that demonstrated excellent concordance with standard 12-lead ECGs for the detection of STEMI as well as non-STEMI ischemic changes. These pilot results suggest that a low cost, convenient alternative to existing ECG technology using now common smartphones and other smart electronic devices may extend the availability of ECG beyond its current reach and facilitate the early

Acknowledgments

Funding: Funds for this study were provided by AliveCor, Inc. in the form of an unrestricted research grant and by providing the research device along with device training. AliveCor, Inc. did not contribute to the study design or execution, data analysis, manuscript preparation, or the decision to submit the manuscript for publication. The authors take full responsibility for manuscript content.

Disclosures: David Albert is the founder and current chief medical officer of AliveCor, Inc. No other

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