Low-voltage potentials contribute to postoperative atrial fibrillation development in obese patients.

BACKGROUND

Obesity predisposes to the development of atrial fibrillation (AF); however, the pathophysiology underlying this relation is only partly understood.

OBJECTIVE

As low-voltage areas are considered indicators of the arrhythmogenic substrates promoting AF, our study aimed to compare the extensiveness of atrial low-voltage areas between obese and nonobese patients by using high-resolution epicardial mapping in order to identify predilection sites of low-voltage areas.

METHODS

A total of 430 patients (131 (30%) obese and 299 (70%) nonobese) were matched resulting in 212 patients (body mass index [BMI] ≥30 kg/m2: n = 106; BMI <30 kg/m2: n = 106) undergoing cardiac surgery (mean age 63 ± 11 years; 161 male). All patients underwent epicardial mapping of the right atrium, Bachmann bundle (BB), and left atrium during sinus rhythm. Low-voltage potentials were defined as potentials with peak-to-peak amplitudes below the fifth percentile of all potential amplitudes obtained from nonobese patients.

RESULTS

Compared with nonobese patients, obese patients have potentials with lower voltages (median of medians) (4.5 mV [0.4-16.2 mV] vs 5.5 mV [0.8-18.0 mV]; P < .001), especially at BB (4.1 mV [0.4-12.3 mV] vs 6.2 mV [1.0-14.3 mV]; P < .001) and left atrium (5.1 mV [0.5-10.1 mV] vs 6.2 mV [0.8-15.9 mV]; P = .003). The percentage of low-voltage potentials was higher in obese (median 3.6% [0.0%-77.1%]) than in nonobese (median 2.3% [0.0%-57.9%]) patients (P < .001), again at BB (obese: 2.9% [0.0%-77.1%] vs nonobese: 0.9% [0.0%-42.0%]; P < .001). Percentages of low-voltage potentials correlated with incidences of conduction block (P < .001), while BMI (P = .044) and low-voltage potentials (P = .001) were independent predictors for the incidence of early postoperative AF.

CONCLUSION

Obesity may predispose to an overall decrease in atrial voltage and a higher percentage in low-voltage potentials. BB was a predilection area for low voltage within the atria of obese patients.