ABC | Volume 111, Nº2, August 2018

Original Article Sampaio et al Monitoring of rhythm, atrial fibrillation and stroke Arq Bras Cardiol. 2018; 111(2):122-131 Figure 3 – PoIP provides daily statistics of connection (blue line) and recoding (green line) data of signal transmission in the server. It is of note that connection and transmission percentages are very similar to each other (day 3/6: 99% and 98%, day 4/6: 92% and 90%, day 5/6: 96% and 96%). Small losses occurred, as on 6/6/2016, when there was a brief period when signal was transmitted but not recorded in the server (arrow) Daily statistics Start 06/03/16 Connection Recording Connection Recording Connection Recording Connection Recording Connection Recording Data 115836688 Data 103018519 Data 112317821 Data 107658637 Data 51120011 Start 06/04/16 Start 06/05/16 Start 06/06/16 Start 06/07/16 Connection 23:49 99% Connection 21:58 92% Connection 22:59 96% Connection 23:04 96% Recording 23:31 98% Recording 21:39 90% Recording 22:59 96% Recording 22:27 94% Recording 10:39 44% Connection 10:50 45% Table 5 – Comparisons between Holter and POIP monitoring results Variable Holter POIP p-value F Atrial fibrillation (< 30 seconds) 1 (1.9%) 7 (13.5%) 0.060 AVC/AIT 1 (3.8%) 6 (23.1%) 0.099 Controls - 1 (3.8%) - First 24h 1 (1.9%) 3 (5.7%) 0.618 Atrial tachycardia 25 (48.1%) 40 (76.9%) 0.004 AVC/AIT 16 (61.5%) 22 (84.6%) 0.116 Controls 9 (34.6%) 18 (69.2%) 0.025 First 24h 25 (48.1%) 26 (50%) 1.000 Frequent SVES* 8 (15.4%) 10 (19.2%) 0.796 AVC/AIT 5 (19.2%) 4 (15.4%) 1.000 Controls 3 (11.5%) 6 (23.1%) 0.465 First 24h 8 (15.4%) 8 (15.4%) 1.000 Frequent atrial tachycardia or SVES 27 (51.9%) 41 (78.8%) 0.007 Stroke/TIA 17 (65.4%) 22 (84.6%) 0.199 Controls 10 (38.5%) 19 (73.1%) 0.025 First 24h 27 (51.9%) 26 (50%) 1.000 Ventricular tachycardia 11 (21.2%) 14 (26.9%) 0.647 Stroke/TIA 6 (23.1%) 7 (26.9%) 1.000 Controls 5 (19.2%) 7 (26.9%) 0.743 First 24h 11 (21.2%) 7 (13.5%) 0.438 Frequent ventricular extrasystoles 13 (25%) 15 (28.8%) 0.825 Stroke/TIA 6 (23.1%) 8 (30.8%) 0.755 Controls 7 (26.9%) 7 (26.9%) 1.000 First 24h 13 (25%) 12 (23.1%) 1.000 SVES: supraventricular extrasystoles; F Fisher’s exact test; *frequent SVES was defined as > de 30 events/hour software in the ward facilities. We found a high signal variation depending on the site where the measurements were obtained – in the entrance, in the middle and in the ward exit, the signal velocity was 1.6, 12.3 and 0.3 Mbs, respectively, and signal strength was 60, 70 and 20%. Such high signal variation may explain signal losses during the monitoring of patients hospitalized in these areas, which would be lower in the outpatient department. In addition, transmission losses may occur even in cases of adequate connectivity between PoIP and the mobile phone provider, due to instability of the mobile phone network. During these unstable periods, PoIP remains connected to the provider, and data transmission is restored when connection is recovered (Figure 3). Although such instability periods, are usually short, in our study, they accounted for 11.4% of total monitoring time, i.e. approximately 19 hours a week 128