Background: Due to the recent rapid increase in the number of patients implanted with pacemakers, cardioverter-defibrillators (ICD), and cardiac resynchronisation therapy devices (CRT), conventional monitoring at specialist clinics is becoming increasingly difficult. The development of technology has enabled remote device monitoring with the use of teletransmission systems.
Aim: To assess the effectiveness of transmission and the possibility of using telemetric data for further clinical management of patients with heart failure (HF) treated with CRT-D.
Methods: The analysis included 305 consecutive patients with chronic HF, New York Heart Association functional classes II-IV, treated with the use of CRT-D by Biotronik or Medtronic in the years 2006-2012. The patients received transmitters, enabling the remote monitoring of the implanted device from the patients' houses. Scheduled reports were automatically sent every month. The triggers for pre-specified emergency alert transmissions were as follows: ventricular tachycardia (VT) or ventricular fibrillation (VF) episodes, CRT-D intervention, ventricular extrasystoles > 110/h, any episode of atrial fibrillation (AF), atrial flutter (AFL) or supraventricular tachycardia, mean heart rate (HR) during, mean 24-h HR, CRT pacing < 95%, Elective Replacement Indicator, or End Of Service and device malfunction. The all-cause mortality of the study population has been assessed at the end of the follow-up period (mean of 20.5 months).
Results: Devices manufactured by Biotronik were provided to 71% of the study population, while 29% received devices by Medtronic. In 97.3% of cases, the monitors were wireless, fully automatic, and capable of immediate data transmission whenever a pre-specified alert notification was fulfilled. The analysis of long-term outcomes revealed that all-cause mortality of the whole study population was 13%. The effectiveness of report transmission was 98%. During follow-up a total of 31,198 transmissions were received and analysed, which constituted, on average, 4.9 transmissions per patient per month. Among analyses, 30% were reports generated by scheduled remote follow-ups, and 70% were caused by unscheduled device alerts. Correct functioning of the system was confirmed; the quality of the received data was 100%. In 63.9% of patients, decisions based on the information obtained from telemonitoring reports were made to modify the therapy, refer the patients to cardiology or electrophysiology clinics, or hospitalise them urgently. The most common medical reaction was device reprogramming (46.8%). Pharmacotherapy was modified in 33.7% of patients: beta-blocker dose increase (25.9%), anticoagulant treatment inclusion (15.7%), amiodarone inclusion (1.9%), or digoxin inclusion (4.5%). The remaining medical responses were referring patients for atrioventricular junction ablation (8.1%), VT ablation (2.9%), or AF/AFl ablation (1.6%).
Conclusions: Remote monitoring of implantable devices is feasible, safe, and effective in supervising patients with CRT-D devices. Daily-based remote monitoring of a large population of HF patients allows continuous "triage" of high-risk patients and selection of individuals who require urgent intervention.
Keywords: cardiac resynchronisation therapy; heart failure; remote monitoring.