Diagnostic Accuracy of a Smartphone-Operated, Single-Lead Electrocardiography Device for Detection of Rhythm and Conduction Abnormalities in Primary Care

Jelle C.L. Himmelreich, MD, MSc; Evert P.M. Karregat, MD, MSc; Wim A.M. Lucassen, MD, PhD; Henk C.P.M. van Weert, MD, PhD; Joris R. de Groot, MD, PhD; M. Louis Handoko, MD, PhD; Robin Nijveldt, MD, PhD; Ralf E. Harskamp, MD, PhD


Ann Fam Med. 2019;17(5):403-411. 

In This Article


We included 219 patients during the period April 2017 to July 2018. After excluding 2 patients for missing 1L- and/or 12L-ECG recordings and 3 patients for nonoverlapping recordings, the remaining 214 patients comprised the study population. No adverse device effects were reported. Baseline characteristics of the included patients are listed in Table 1. Mean age was 64.1 ± 14.7 years, and 53.7% of the patients were male. As shown in Figure 2, the indication for performing 12L-ECG was symptom driven for one-half of the patients (n = 108). Among those presenting with new symptoms, most (44.4%) reported palpitations as the primary symptom (Table 2). The 12L-ECG recordings revealed that AF/AFL, any rhythm abnormality, and any conduction abnormality were present in 23, 44, and 28 patients, respectively (Table 3).

Figure 2.

Study flow diagram.
1L = single-lead; 12L = 12-lead; ACA = any conduction abnormality; AF = atrial fibrillation; AFL = atrial flutter; ARA = any rhythm abnormality; bpm = beats per minute; ECG = electrocardiography; PCP = primary care physician.

Diagnostic Accuracy of the 1L-ECG

Data on diagnostic accuracy with calculated 95% CIs are summarized in Table 4. The 2×2 contingency tables with detailed information, including the rhythm diagnoses of all true positives, false negatives, and false positives, can be found in Supplemental Figure 1, http://www.AnnFamMed.org/content/17/5/403/suppl/DC1/.

For the primary outcome of AF/AFL, we found that cardiologists were able to correctly classify all 23 cases using 1L-ECG, resulting in a sensitivity and a specificity of 100%. The smartphone-integrated algorithm correctly identified 20 of 23 AF cases and incorrectly classified 4 cases of sinus rhythm as possible AF (sensitivity: 87%; specificity: 97.9%). Interpretation of 1L-ECG was less robust for the secondary endpoints of any rhythm abnormality (sensitivity: 90.9%; specificity: 93.5%) and any conduction abnormality (sensitivity: 46.4%; specificity: 100%). Explicitly for ectopic beats, 1L-ECG correctly classified 20 of 23 cases of known ectopic beats. The false positives for the outcome any rhythm abnormality could all be attributed to misclassified ectopic beats (n = 11).

Additional Analyses

The stratified analysis according to indication for ECG (symptom or protocol driven) and the sensitivity analysis in which we excluded truncated 1L-ECG recordings (n = 6) rendered similar results (see Supplemental Figure 2, Supplemental Table 1, and Supplemental Table 2, respectively, http://www.AnnFamMed.org/content/17/5/403/suppl/DC1/).