Table 2.
Alerts sent to investigational sites by the central monitoring unit in IN-TIME: definitions and occurrencesa
| Alert type | Device/HMSC: alert setting | CMU activity in a patient with HMSC alert | CMU: condition for SOP compatible event | Number of alerts (number of patients) |
|---|---|---|---|---|
| Atrial tachyarrhythmia | 109 (65) | |||
| First onset of AF for >30 s in patients with no prior documented AF | Device: IEGM for atrial monitoring episode | Check IEGM for atrial monitoring episode in patients with no prior documented AF | IEGM shows true AF | 31 (31) |
| HMSC: sends alert | ||||
| Long atrial arrhythmia episode (>6 h) with high-ventricular rate (>120 b.p.m.) | HMSC: alert for atrial burden >6 h with ventricular rate >120 b.p.m. | Check IEGM | Ventricular rate >120 b.p.m. | None |
| Daily AF burden >50% on 7 consecutive days after a period of 4 weeks with burden <25% for patients with known AF | HMSC: alert for atrial burden >6 h | Check trend graph | Atrial burden ≥50% on 7 consecutive days | 20 (16) |
| Atrial arrhythmia in the VT zone | HMSC: VT zone detected | Check IEGM | Suspicious IEGM | 1 (1) |
| First onset of AF for >30 s in patients with prior documented AF | Device: IEGM for atrial monitoring episode | Check IEGM for atrial monitoring episode | Not predefined | 22 (22) |
| HMSC: alert for atrial monitoring episode | ||||
| Atrial episode | HMSC: alert for atrial monitoring episode | Check IEGM for atrial monitoring episode | Not predefined | 22 (14) |
| Atrial burden >50% for more or less than 1 week | HMSC: alert for atrial burden ≥6 h | Check trend graph | Not predefined | 13 (8) |
| Ventricular tachyarrhythmia or ICD shock | 56 (42) | |||
| ≥3 VT2/VF episodes over 48 h | HMSC: alerts for VT2 and VF detection | Check IEGM for appropriateness and count true VT/VF episodes in 48 h | ≥3 episodes within 48 h | 7 (6) |
| First ICD shock in spontaneous episode | HMSC: alert for VT and VF detections | Check if the episode was induced or spontaneous | Spontaneous episodes with shock | 22 (22) |
| First occurrence of slow VT (<150 b.p.m.) | HMSC: alert for VT1 (monitoring zone) | Check IEGM if true VT | True VT <150 b.p.m. | 8 (8) |
| VT/VF detection with suspicious IEGM (e.g. sensing issue or inappropriate detection) | HMSC: alert for VT and VF detections | Check IEGM | Suspicious IEGM | 2 (2) |
| <3 VT/VF episodes over 48 h | HMSC: alert for VT and VF detections | Check IEGM | Not predefined | 18 (14) |
| Ineffective ICD shock | HMSC: ineffective shock | Check IEGM | Not predefined | 2 (2) |
| VT and low CRT pacing | HMSC: alert for VT and low CRT | Check IEGM | Not predefined | 1 (1) |
| Low percentage of CRT pacing | 91 (35) | |||
| CRT pacing <80% over 48 h | HMSC: alert for CRT pacing <80% | Check CRT pacing on the day before | CRT pacing <80% on two consecutive days | 81 (30) |
| CRT pacing <80% combined with IEGM | HMSC: alert for CRT pacing <80% | Check IEGM | Suspicious IEGM | 3 (3) |
| CRT pacing <80% over 24 h | HMSC: alert for CRT pacing <80% | Check trend graph | Not predefined | 8 (7) |
| CRT pacing <80% and ventricular or atrial arrhythmia | HMSC: alert for CRT pacing <80% | Check IEGM | Not predefined | 2 (2) |
| Ventricular extrasystoles | 54 (46) | |||
| Visible upward trend in VES/h over 7 days | Not programmable | Check trend graph weekly | Visible trend | 39 (34) |
| VES >110 per hour for more than 10 days | Not programmable | Check trend graph | Not predefined | 15 (15) |
| Physiological trends | 2 (2) | |||
| Visible downward trend in patient activity over 7 days | Not programmable | Check rend graph weekly | Visible trend | 1 (1) |
| Rising mean heart rate | Not programmable | Check trend graph | Not predefined | 1 (1) |
| Lead related measurements and IEGMs | 98 (58) | |||
| Suspicious IEGMb | HMSC: alert for any new IEGM | Check IEGM | Suspicious IEGM | 25 (18) |
| RA amplitude | HMSC: programmable | Check trend graph | <0.5 mV | 13 (9) |
| RV amplitude | HMSC: programmable | Check trend graph | <2.0 mV | 22 (18) |
| RV pacing threshold | HMSC: programmable | Check trend graph | Safety margin <1 V | 11 (10) |
| RV impedance | HMSC: programmable | Check trend graph | <250 or >1500 Ohm | 1 (1) |
| LV amplitude | HMSC: programmable | Check trend graph | <2.0 mV | None |
| LV impedance | HMSC: programmable | Check trend graph | <250 or >1500 Ohm | 2 (2) |
| LV pacing threshold | HMSC: programmable | Check trend graph | Safety margin <1 V | 12 (8) |
| Shock impedance | HMSC: programmable | Check trend graph | <30 or >125 Ohm | 13 ( 5) |
| Gaps in data transmission | 818 (241) | |||
| Missing HM messages for 3 days | HMSC: alert for missing messages for 3 days | Check if the patient is known to be on holidays or in hospital | If the patient is not known to be absent | 818 (241) |
| Technical alerts | None | |||
| Elective replacement indicator | HMSC: programmable | None | ||
| Technical alert | HMSC: programmable | None | ||
Sums of numbers of alerts do not match completely because few alerts are contained in more than one category, and three alerts contained no description of the content.
CMU, central monitoring unit; ICD, implantable cardioverter-defibrillator; HM, Home Monitoring; SOP, standard operating procedure defined in the study protocol; VT, ventricular tachycardia; AF, atrial fibrillation; CRT, cardiac resynchronization therapy; IEGM, intracardiac electrogram; LV, left ventricular; RA, right atrial; RV, right ventricular; VES, ventricular extrasystoles; VF, ventricular fibrillation; VT1/VT2, slow/fast ventricular tachycardia.
a
During the randomized period in the RM group.
b
T-wave oversensing, far-field atrial sensing of ventricular activity, or other suspected sensing problem.