Dynamic evaluation of atrial fibrillation risk factors using multiple sensors of implantable cardioverter defibrillators

The HEAD2TOES schema was introduced to identify modifiable risk factors (RF) for atrial fibrillation (AF), including heart failure (HF), physical inactivity (PA), and sleep apnea (SA). Modern implantable cardioverter-defibrillators (ICDs) can detect SA, assess HF status, and measure daily PA. This study investigates the relationship between atrial high-rate episodes (AHREs) and ICD-detected surrogates for these RF in HF patients.

Data were collected from 411 HF patients with ICDs. The HeartLogic Index measured HF status, Respiratory Disturbance Index (RDI) severe SA (≥30episodes/hour), and accelerometer detected reduced PA (≥1 h/day). Endpoints were daily AHRE burdens ≥ 5 min and ≥ 23 h. Over 26 months of median follow-up, IN-alert-HF state was 13 % of the total observation time, RDI ≥ 30 episodes/h occurred 58 % of time, and 2 % of weekly activity values were ≥ 1 h lower than usual. AHRE burden ≥ 5 min/day occurred in 139 (34 %) patients and ≥ 23 h/day in 68 (17 %). Both IN-alert-state and reduced activity were independently associated with AHRE burden (≥5 min/day and ≥ 23 h/day), while RDI ≥ 30episodes/hour was associated only with AHRE ≥ 5 min/day. We defined a score predicting AHRE burden ≥ 5 min (2*HeartLogic_IN-alert + 1*RDI ≥ 30episodes/hour + 4*Reduction_in_activity ≥ 1 h), and a score predicting AHRE burden ≥ 23 h (1*HeartLogic_IN-alert + 2*Reduction_in_activity ≥ 1 h). Lower score levels (AHRE-5 min < 4 and AHRE-23 h < 2) comprised the largest proportion of follow-up duration (98 %), with higher scores linked to higher incidence rate ratios for AHRE (6.75 [95 %CI:1.88-20.16] and 11.46 [95 %CI:3.34-31.72], respectively).

In HF patients, AHRE occurrence is independently associated with ICD-detected HF status, severe SA, and decreased PA. These ICD-indexes might serve as surrogates for HEAD2TOES RF, aiding in continuous AF risk assessment.