136-73: Clinical comparison of standard and derived 12 lead electrocardiograms registered by EASI electrocardiogram technology using the CardioSecur system

Abstract

Purpose: To investigate differences during sinus rhythm between clinical 12-lead standard ECG and derived 12-Lead electrocardiograms (ECG) registered by a simplified 3-lead setting with four electrodes. Methods: The ECG recordings during sinus rhythm of 40 consecutive patients were analyzed. A certificated nurse subsequently used a standard 12-lead ECG (Schiller) machine and the CardioSecur ECG system to obtain the recordings. The CardioSecur system derives a 12 lead ECG using validated EASI-ECG technology by only four electrodes and 3 leads. ECG recording speed was set at 25mm/s and amplitude at 10mm/mV. The following ECG parameters were analyzed and compared: p wave amplitude (mV), duration of p wave, PQ, QRS, QT, QTc (ms), heart rate (ms), p wave and QRS axis, polarity of T waves, presence of Q waves and QRS transition zone in chest leads. Each ECG parameter was manually measured and analyzed in several leads using a standard caliper. Statistics were done using SPSS. Results: ECG recordings were analyzed and compared in 37 patients. Time between subsequent ECG - 39 minutes on average. P wave amplitude (mV): 12 lead standard ECG 0.14 ± 0.05 and CardioSecur ECG 0.16 ± 0.06, difference between them -0.02± 0.06 (p < 0.05). P wave duration (ms): 86 ± 26 and 78 ± 19; difference 8 ± 17 (p = 0.007). PQ interval (ms): 191 ± 49 and 176 ± 45; 15 ± 30 (p = 0.008). QRS (ms): 78 ± 22 and 80 ± 24; -2 ± 12 (p = ns). QT interval (ms): 389 ± 37 and 369 ± 38; 20 ± 33 (p = 0.002). QTc interval duration (ms): 415 ± 36 and 401 ± 38; 14 ± 38 (p = 0.05). Heart rate (ms): 891 ± 155 and 856 ± 142; 35 ± 114 (p = ns). P wave axis (degrees): 60 ± 28 and 55 ± 67; 5 ± 65 (p = ns). QRS axis (degrees): 37 ± 40 and 40 ± 38; -1.9 ± 23 (p = ns). QRS transition zone in chest leads: 3 ± 0.9 and 3 ± 0.9; 0 ± 0.8 (p = ns).Presence of Q waves (mV) in 12 lead standard ECG and CS ECG of lead I: 0.02 ± 0.03 and 0.09 ± 0.3; difference -0.07 ± 0.3 (p = ns). Lead II: 0.03 ± 0.03, 0.1 ± 0.2; -0.09 ± 0.1 (p = 0.001). Lead III: 0.02 ± 0.04, 0.16 ± 0.2; -0.14 ± 0.2 (p = 0.000). Lead aVL: 0.06 ± 0.1, 0.01 ± 0.03; 0.05± 0.1 (p = 0.03). Lead aVF: 0.02 ± 0.03, 0.15 ± 0.2; -0.13 ± 0.2 (p = 0.000). Lead V3: 0.001 ± 0.005, 0.02± 0.09; 0.019 ± 0.1 (p = ns). Lead V4: 0.006 ± 0.02, 0.04 ± 0.1; -0.03 ± 0.1 (p = ns). Lead V5: 0.02 ± 0.03, 0.09 ± 0.2; -0.07 mV ± 0.18 (p = 0.03). Lead V6: 0.02 ± 0.04, 0.05 ± 0.09; -0.03mV ± 0.07 (p = 0.009). T wave polarity measurement showed significant positive correlation between leads I, V3 and V6 (p < 0.05), nonsignificant positive correlation in leads II, III,aVF, aVL, V2, V4 and V5. However, in lead V1 CardioSecur ECG T waves were significantly more positive (p 0.028). Conclusion: When comparing 12 lead ECG measurements by standard equipment in sinus rhythm to registrations produced by the CardioSecur system, a fairly good correlation can be found at first sight. However, when looking more into detail of the recordings, several significant differences appear. P wave amplitude seems to be higher, P wave, PR and QTc interval are shorter, T waves more positive in lead V1 and more pronounced Q waves can be found in inferior leads in the CardioSecur system. These findings need to be taken into account when interpreting CardioSecur registrations as a substitute of a classical 12 lead ECG recording.