Daily ECG Versus 7-day Holter ECG After Atrial Fibrillation Ablation

Daily ECG transmission versus serial 7-day Holter ECG for assessment of efficacy of ablation for atrial fibrillation - the AGNES-ECG study

Introduction. The optimal method for the assessment of efficacy of ablation for atrial fibrillation (AF) has not yet been established. The symptom-based evaluation is not accurate because many AF episodes are asymptomatic. It has been well documented that the more frequent and/or longer ECG recording the more the AF recurrences are detected. However, such devices for long-term ECG monitoring as implantable loop recorders are expensive whereas external ECG monitoring is not well tolerated over a period longer than one month. The most frequently used approach is periodic 1-7 day Holter ECG monitoring, usually performed 3, 6 and 12 months after the procedure and additional standard ECG recordings when symptoms occur [1]. Using this method, asymptomatic AF episodes occurring between Holter ECG recordings are missed.

Recently, several types of external ECG recorders have been introduced, enabling good quality frequent ECG recordings and transmission via mobile phones. Only a few studies documented the usefulness of this method in detecting silent AF in a high-risk population [2], however, the value of short but frequent ECG recordings after AF ablation has not yet been established. Kimura et al. [3] tested three methods for AF detection after ablation in 30 patients. The follow-up lasted 6 months and each patient underwent three types of ECG recordings (1) repeated 10-second standard ECG recordings, obtained during outpatient visits, (2) 24-hour Holter ECG performed every month and (3) short 30-second ECG recordings performed twice daily and when symptoms occur, transmitted by telemetry. As expected, the latter method enabled detection of the highest number of AF episodes, however, the number of recordings declined steadily throughout the period of the study, suggesting some technical difficulties with performing recordings and decreased patient compliance.

Similar study was conducted by Senatore et al. [4] who compared diagnostic yield of twice daily ECG tele-transmission versus repeated 24 hour ECG recordings in 72 patients after AF ablation. Using daily ECG transmissions, significantly more patients had AF episodes detected (27.8% vs 13.9%, p = 0,001). In another study [5] twice daily ECG transmissions using smartphone and AliveCor system were compared with standard medical care in patients with a history of AF undergoing ablation or cardioversion. Also in this study frequent ECG transmissions using smartphone occurred more effective in detecting AF recurrences than standard care (61% vs 30%; P = 0,04).

In summary, data on the optimal type of ECG monitoring after AF ablation are scarce. It seems that frequent, short ECG recordings have more diagnostic yield than 24-hour ECG monitoring, even when performed monthly, or standard care with recording ECG only when symptoms suggesting AF occur. However, the optimal mode of monitoring is not known. Such questions as whether once-a-day ECG transmission is enough and whether longer i.e. 7-day Holter ECG may be as valuable as daily ECG transmissions, remain unanswered.

Aim: to compare daily ECG transmissions with repeated 7-day Holter ECG in detecting AF episodes following AF ablation.

Hypothesis: daily ECG recordings have significantly higher yield in AF detection than repeated 7-day Holter ECG.

Methods:

Patients:

The study group will consists of 50 consecutive patients undergoing AF ablation in the investigator's center. The follow-up will last 12 months. The AF detection will be performed using two recording methods in each patient. The number of 50 patients has been chosen based on the assumption that Holter ECG will detect AF recurrence in 15% of patients and daily transmission will detect AF recurrence in 38% patients (alfa error = 0.05 and beta error = 0.2)

Daily ECG recordings and transmissions will be performed using the HR-2000 recorder (ISTEL, Poland). This device enables recording of 30 seconds of 6-channel ECG (I, II, III, aVR, aVL, aVF) from 4 metal electrodes build in the recorder. In order to record ECG, the device is activated by a patient and attached to the thorax, at the area of sternum. The duration of recording may vary from 30 seconds to 3 minutes, however, only 30-second recordings will be used in the present study. After recording, ECG will be transmitted using Bluetooth to patient's smartphone and then transmitted to the central station where they will be stored and analyzed. Analysis will be performed on a daily basis by an experienced ECG technician, not directly involved in patient's recruitment and treatment. The results of all recordings will be available for study team after 3, 6 and 12 months after ablation, at the time when concurrent Holter ECG recordings will be analyzed. Only in case of serious, life-threatening arrhythmias (non-sustained or sustained ventricular tachycardia, or pauses > 6 seconds) the study team will be informed immediately by a technician about the results of 30-second ECG recording in order to undertake proper action. Specifically, asymptomatic episodes of AF will not be unblinded to the study team in order not to interfere with medication and to allow continuing follow-up till next Holter ECG monitoring.

The second method of ECG recording will be 7-day Holter ECG (DMS 300-4A recorders, DM Software, NV, USA) performed 3, 6 and 12 months after ablation.

The patients will be allowed to record additional ECG when symptoms suggesting AF occur. This may be performed by ISTEL recorder or standard 12-lead ECG if available.

At each time-point (3, 6 and 12 months) the study team will analyze all recorded ECGs and 7-day Holter ECG, and make appropriate therapeutic decisions.

Inclusion criteria

• AF ablation 1-3 days prior to inclusion
• Access to smartphone and ability to maintain ISTEL recorder and transmitting ECG.

Exclusion criteria

.

• Pacemaker implanted.
• Known presence of other than AF cardiac arrhythmias requiring frequent ECG monitoring (ventricular arrhythmia, second or third-degree atrioventricular block)
• Lack of smartphone or inability to manage ISTEL recorder.

• Primary end-point: Time to detection of first AF episode after ablation 2. Secondary end-point: Number of patients with AF recurrence after ablation Number of patients with asymptomatic AF recurrence after ablation

Definitions AF episode - episode lasting ≥30 seconds Study period: August 2018 - August 2020

Inclusion criteria

• AF ablation 1-3 days prior to inclusion
• Access to smartphone and ability to maintain ISTEL recorder and transmitting ECG.

Exclusion criteria

• Pacemaker implanted.
• Known presence of other than AF cardiac arrhythmias requiring frequent ECG monitoring (ventricular arrhythmia, second or third-degree atrioventricular block)
• Lack of smartphone or inability to manage ISTEL recorder.