Atrial fibrillation variability on long-term monitoring of implantable cardiac rhythm management devices

Change in Atrial Fibrillation Burden over Time in Patients with Nonpermanent Atrial Fibrillation

Introduction

The natural course of atrial fibrillation (AF) is not well defined. We aimed to investigate the change in AF burden over time and its associated risk factors among AF patients.

Methods

Fifty-four participants with recently documented paroxysmal or persistent AF were enrolled. Main exclusion criteria were permanent AF or previous catheter ablation for AF. AF burden was calculated as time in AF divided by total recording time using yearly continuous 7-day Holter-ECG recordings. A relative change ≥10% or an absolute change >0.5% in AF burden between two yearly Holter-ECG recordings was considered significant.

Results

Mean age was 67 years, 72% were men. The proportion of patients with no recorded AF increased from 53.7% at baseline to 78.6% (p=0.1) after 4 years of follow-up. In 7-day Holter-ECG recordings performed after baseline, 23.7% of participants had a decrease and 23.7% an increase in AF burden. In separate mixed effect models, AF burden over time was associated with prior stroke (β 42.59, 95% CI (23.40; 61.77); p < 0.0001), BNP (β 0.05, CI (0.02; 0.09); p=0.005) end-diastolic (β 0.49, CI (0.23; 0.74); p=0.0003) as well as end-systolic (β 0.25, CI (0.05; 0.46); p=0.02) left atrial volume, left atrial ejection fraction (β −0.43, CI (−0.76;−0.10); p=0.01), E-wave (β 36.67, CI (12.96; 60.38); p=0.003), and deceleration time (β −0.1, CI (−0.16; −0.05); p=0.002). In a multivariable model, a history of prior stroke (β 29.87, CI (2.61; 57.13); p=0.03) and BNP levels (β 0.05, CI (0.01; 0.08); p=0.007) remained significantly associated with AF burden.

Conclusions

Few patients with paroxysmal or persistent AF have AF episodes on yearly 7-day Holter-ECG recordings, and AF progression is rare. AF burden was independently associated with a history of prior stroke and BNP levels.

Stroke Risk as a Function of Atrial Fibrillation Duration and CHA 2 DS 2 -VASc Score

Background:

Studies of patients with cardiovascular implantable electronic devices show a relationship between atrial fibrillation (AF) duration and stroke risk, although the interaction with CHA 2 DS 2 -VASc score is poorly defined. The objective of this study is to evaluate rates of stroke and systemic embolism (SSE) in patients with cardiovascular implantable electronic devices as a function of both CHA 2 DS 2 -VASc score and AF duration.

Methods:

Data from the Optum electronic health record deidentified database (2007–2017) were linked to the Medtronic CareLink database of cardiovascular implantable electronic devices capable of continuous AF monitoring. An index date was assigned as the later of either 6 months after device implantation or 1 year after electronic health record data availability. CHA 2 DS 2 -VASc score was assessed using electronic health record data before the index date. Maximum daily AF burden (no AF, 6 minutes–23.5 hours, and >23.5 hours) was assessed over the 6 months before the index date. SSE rates were computed after the index date.

Results:

Among 21 768 nonanticoagulated patients with cardiovascular implantable electronic devices (age, 68.6±12.7 years; 63% male), both increasing AF duration ( P <0.001) and increasing CHA 2 DS 2 -VASc score ( P <0.001) were significantly associated with annualized risk of SSE. SSE rates were low in patients with a CHA 2 DS 2 -VASc score of 0 to 1 regardless of device-detected AF duration. However, stroke risk crossed an actionable threshold defined as >1%/y in patients with a CHA 2 DS 2 -VASc score of 2 with >23.5 hours of AF, those with a CHA 2 DS 2 -VASc score of 3 to 4 with >6 minutes of AF, and patients with a CHA 2 DS 2 -VASc score ≥5 even with no AF.

Conclusions:

There is an interaction between AF duration and CHA 2 DS 2 -VASc score that can further risk-stratify patients with AF for SSE and may be useful in guiding anticoagulation therapy.

Atrial fibrillation variability on long-term monitoring of implantable cardiac rhythm management devices

BACKGROUND

Atrial fibrillation (AF) burden and duration are predictors of thromboembolic events. The random nature of these measures may affect clinical decision making. The objective of this study was to determine temporal changes in AF burden as detected by continuous monitoring.

HYPOTHESIS

AF burden changes over time when detected by continuous monitoring.

METHODS

A post hoc analysis of patients enrolled in the TRENDS (A Prospective Study of the Clinical Significance of Atrial Arrhythmias Detected by Implanted Device Diagnostics) study with ≥1 stroke risk factor(s) who were implanted with a dual-chamber cardiac rhythm management device (CRMD) and had AF burden data available for ≥2 years was performed. AF burden was defined as no AF, low AF (<5.5 hours on any given day), or high AF burden (≥5.5 hours in a day), and was first assessed over the initial 30 days following enrollment and then reassessed at 6-month intervals for 2 years.

RESULTS

Among 394 patients included, the average age was 70.2 ± 10.9 years, 71% were male, and mean CHA2 DS2- VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke or TIA, vascular disease, age 65-74 years, sex category) score was 3.7 ± 1.6. In the 30-day baseline period, 75.1% of patients had no AF, 11.2% had low AF, and 13.7% had high AF. Over the subsequent 2 years, 40.0% of patients initially classified as no AF or low AF experienced periods with high AF, whereas 59.3% of patients initially classified as high AF experienced ≥6 consecutive months with no AF or low AF. Advanced age was the sole predictor of AF progression.

CONCLUSIONS

Significant temporal variability in AF burden exists when measured continuously with an implantable CRMD.