Performance of Single-Lead Handheld Electrocardiograms for Atrial Fibrillation Screening in Primary Care

Central Illustration. Study Overview and Predictive Values of AliveCor Algorithm Interpretations (A) An overview of the current study. A total of 38,190 handheld 1L ECG tracings were generated in the context of screening within the VITAL-AF trial. Of these, we excluded tracings performed among individuals with known AF at the time of screening, as well as those overread as uninterpretable by cardiologist readers, resulting in 31,376 tracings in the primary analysis (see text). We quantified the test characteristics of the AliveCor 1L ECG algorithm against cardiologist overread (primary analysis), against electrophysiologist overread (secondary analysis), and against clinical interpretation of a 12-lead ECG performed on the same day as screening (secondary analysis). (B) The positive predictive values (PPVs) (red) and negative predictive values (NPVs) (green) for the 4 AliveCor automated 1L ECG interpretations (x-axis), using cardiologist overread as the gold standard. Only PPV is depicted for possible AF, which always denotes a positive test, while only NPV is depicted for normal which always denotes a negative test. Since unclassified and no analysis represent equivocal findings, both PPV and NPV are…

Figure 1. Distribution of AliveCor Algorithm Interpretations Stratified by Cardiologist Overread Depicted is the distribution of AliveCor interpretations (see legend), stratified by cardiologist overread as AF (right bar) vs non-AF (left bar). The proportion of tracings represented by each AliveCor interpretation within each stratum of cardiologist overread is depicted within the corresponding bar, with the exception of not AF–possible AF (1.3%) and not AF–no analysis (1.8%), which are unlabeled for graphical purposes. AF = atrial fibrillation.

Figure 2. Frequency of Unclassified and No Analysis Tracings Stratified by Age of Screening (A) The frequency of equivocal tracings (ie, unclassified or no analysis, orange) as a fraction of the total tracings taken (gray) within each subgroup of age (x-axis). (B) The frequency of tracings overread as AF (red) as a fraction of the total number of equivocal tracings (green) observed within each subgroup of age (x-axis). Percentages depict the minority fraction (ie, proportion of equivocal tracings in A and proportion of tracings read as AF in B). AF = atrial fibrillation.

Figure 3. Effect of Unclassified and No Analysis Tracings on 1L ECG Diagnostic Performance Stratified by Age of Screening Depicted are the test characteristics (sensitivity, top left; positive predictive value [PPV], top right; specificity, bottom left, negative predictive value [NPV], bottom right) of the AliveCor 1L ECG algorithm using cardiologist overread as the gold standard. In each plot, the relevant metric is plotted across age group (X-axis), and stratified by whether equivocal tracings (ie, unclassified or no analysis) are considered positive vs negative results. In each plot, the hashed horizontal line depicts the corresponding estimate in the overall sample. ECG = electrocardiogram.