Obesity as a predictor of electrophysiological instability in patients with paroxysmal atrial fibrillation

Introduction Obesity is a significant cardiovascular risk factor, affecting the electrophysiological properties of the heart and promoting arrhythmogenesis. Increased body weight may alter neurohormonal balance, enhance sympathetic activity, and reduce HR variability, leading to longer AF episodes. Objective To evaluate the impact of obesity on heart rhythm parameters in paroxysmal AF and identify predictors of prolonged paroxysms (>30 seconds). Materials and methods A retrospective analysis of 24-hour Holter ECG was conducted in 70 paroxysmal AF patients. They were divided by paroxysm duration: group 1 (< 30 sec, n=50 (71.4%) and group 2 (> 30 sec, n=20 (28.6%) patients, (x² = 12.86, p < 0.05). No significant difference in gender (men: 20 (40.0%) vs. 10 (50.0%), x² = 0.50, p = 0.48) or age (62.2 ± 12.5 vs. 64.3 ± 11.0 years, p = 0.54). Body mass index (BMI, kg/m2) categories: BMI < 25 (n = 14 (20%), 25-29.9 (n = 29 (41.4%), ≥ 30 (n = 27 (38.6%) patients), p>0.05). Results Obese patients had more frequent AF paroxysms/day (7.8 ± 3.1 vs. 5.2 ± 2.3, p = 0.01) and a greater % of time spent in AF (16.3 ± 4.8% vs. 11.9 ± 4.4%, p = 0.02). AF was more prevalent at night in obese patients (27(48.1%) vs. 43(42.0%), p = 0.03). Obese patients had a lower circadian index (1.08 ± 0.12 vs. 1.29 ± 0.15, p < 0.001) and higher mean HR during AF (126.8 ± 15.2 vs. 118.4 ± 13.5 bpm, p = 0.012). Obese patients had higher SPB frequency (14,800 ± 5,200 vs. 12,500 ± 4,500 per day, p = 0.02), more paired ventricular PBs (21.3% vs. 10.4%, p = 0.019) and higher bigeminy incidence (28.4% vs. 15.2%, p = 0.041). PQ interval >220 ms was occurred in 17.2% of obese patients and correlated with SPB >5,000 per day (p = 0.045). Predictors of prolonged AF (>30 sec): each 1 kg/m² BMI increase was linked to higher AF risk >30 sec (OR = 1.12, 95% CI: 1.02-1.25, p = 0.03). Patients with AF >15% of the day had 2,41 greater risk (95% CI: 1.35-4.30, p = 0.01). Circadian index <1.15 increased risk 1.9-fold (OR = 1.89, 95% CI: 1.12-3.15, p = 0.02). Each 10 ms PQ increase associated with prolonged AF >30 sec (OR = 1.21, 95% CI: 1.05-1.38, p = 0.04). Conclusions Obesity is associated with greater electrophysiological instability in AF patients, marked by higher AF frequency, % of time in AF, circadian disruption, increased SPBs, higher-grade VPBs and prolongation of the PQmin interval. Predictors of AF progression include increased BMI, reduced circadian index, higher % of time in AF, prolongation of the PQmin. The results highlight importance of close HR monitoring in obese patients and support personalized risk stratification approach.