David E. Albert

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

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.

Advanced time-frequency methods for signal-averaged ECG analysis

Frequency-domain techniques have been extensively investigated for the analysis of high-resolution electrocardiograms (ECGs), although the merit of frequency-domain analysis is still subject to controversy. Time-frequency analysis methods, which estimate the frequency content of a signal as a function of time, potentially provide even more information for improved ECG analysis. Some researchers report impressive results in predicting the outcome of electrophysiologic studies using the short-time Fourier transform (spectrogram). Other time-frequency representations, such as the Wigner distribution, short-time spectral estimators, and the wavelet transform, have also been investigated. The authors present a unified overview of time-frequency representations, showing that only four classes characterize most time-frequency representations. The authors describe the advantages and drawbacks of the various approaches and speculate on their promise for ECG analysis. Very preliminary experiments in applying some of these techniques to the prediction of the outcome of electrophysiologic studies have suggested some possible new research directions.

Spectral Estimation of the Electrocardiogram

Langner introduced the idea of a high fidelity electrocardiogram (ECG) using an oscilloscope display and a film recorder.’ Subsequently, he examined this high resolution ECG in the context of myocardial infarction2q3 and coronary artery disease4 and concluded that slurs and notches within the QRS complex were strongly correlated with the presence of disease. This association was strengthened by Flowers et al. with correlation between QRS notching and anatomic identification of infarct scam5-’ Initial approaches for quantifying the spectrum of these notches and slurs in the Q R S complex were done with narrow band analog filters in an attempt to characterize the frequency bands of normal and notched QRS complexes.89 Subsequently, the use of digital computers gave rise to the discrete Fourier transform (DFT) method of spectral estimation.” These methods, for the most part, were applied to the QRS complex for analysis. Two trends in cardiac electrophysiology gave rise to a reexamination of spectral estimation of the ECG. The first was the maturing of invasive cardiac electrophysiology and the study of arrhythmogenesis. Directly recorded cardiac electrograms identified arrhythmia substrates where slow conduction and nonuniform propagation occur. The second trend was the development of high resolution ECGs (HRECG) using computer implemented signal averaging to improve the signal-to-noise ratio of the ECG and allow the identification of very low level signals. The most common application of this methodology is the identification of signals after the QRS complex.”-” These “late potentials” have been extensively studied in various clinical populations and are assumed to originate from damaged or diseased regions of the ventricles such as the surviving border zones of myocardial infarction scars. Thus the notches and slurs identified in the earliest studies may likely originate in these regions and late potentials are those that occur latest in the cardiac cycle. Goldberger et al. applied Fourier analysis to signal averaged ECGs but did not consider late po ten t ia l~ . ’~*’~ High pass filtering has been considered a necessary tool for

Smartphone ECG for evaluation of ST-segment elevation myocardial infarction (STEMI): Design of the ST LEUIS International Multicenter Study

In patients experiencing an ST-elevation myocardial infarction (STEMI), rapid diagnosis and immediate access to reperfusion therapy leads to optimal clinical outcomes. The rate-limiting step in STEMI diagnosis is the availability and performance of a 12-lead ECG. Recent technology has provided access to a reliable means of obtaining an ECG reading through a smartphone application (app) that works with an attachment providing all 12-leads of a standard ECG system. The ST LEUIS study was designed to validate the smartphone ECG app and its ability to accurately assess the presence or absence of STEMI in patients presenting with chest pain compared with the gold standard 12-lead ECG. We aimed to support the diagnostic utility of smartphone technology to provide a timely diagnosis and treatment of STEMI. The study will take place over 12months at five institutions. Approximately 60 patients will be enrolled per institution, for a total recruitment of 300 patients.

Debatable issues in automated ECG reporting

Although automated ECG analysis has been available for many years, there are some aspects which require to be re-assessed with respect to their value while newer techniques which are worthy of review are beginning to find their way into routine use. At the annual International Society of Computerized Electrocardiology conference held in April 2017, four areas in particular were debated. These were a) automated 12 lead resting ECG analysis; b) real time out of hospital ECG monitoring; c) ECG imaging; and d) single channel ECG rhythm interpretation. One speaker presented the positive aspects of each technique and another outlined the more negative aspects. Debate ensued. There were many positives set out for each technique but equally, more negative features were not in short supply, particularly for out of hospital ECG monitoring.