Quality of ECG monitoring with a miniature ECG recorder

Background: Long-term monitoring of patients at risk of arrhythmias would benefit from a miniaturized device. This study evaluated the quality of electrocardiogram (ECG) signals recorded by a miniaturized ECG recorder. Methods: ECG data were concurrently recorded with an investigational device (Philips Medical Systems, Seattle, WA, USA) and a Holter recorder from patients with cardiac-related symptoms at the emergency department of a tertiary care university hospital. The device was attached in one of four locations (L1: below left clavicle, L2: midsternal, L3: below left breast, L4: left anterior axillary line in 5th intercostal space). Selected ECG strips were analyzed for atrial activity, QRS width, and basic rhythm by two physicians. Patients were divided into groups based on their number of strips (A 2-5, B 6-9, C 10-21) for descriptive presentation of the data. For statistical analyses, nonlinear mixed-effects models were used. Results: In 90 patients, 574 pairs of strips were analyzed. In L1 (n = 37), agreement between the device and the Holter recorder on presence of P wave was 58-80% in groups A-C and in L2 (n = 28):94-98%, L3 (n = 12):30-72%, and L4 (n = 13):0-70%; on PR interval in L1:58-80%, L2:94-98%, L3:30-62%, and L4:0-70%; on rhythm in L1:56-79%, L2:94-98%, L3:30-62%, and L4:0-70%; on QRS width in L1:86-100%, L2:88-98%, L3:100%, and L4:96-100%. The agreement of L2 in the parameters P wave, PR interval, and rhythm diagnosis was better than in the other locations (P < 0.01). Conclusions: A miniature ECG monitor provided accurate assessment of atrial beats and rhythm diagnosis at a midsternal location and of QRS width at all locations.