Acute exposure to air pollution triggers atrial fibrillation

Abstract

Objectives: This study sought to evaluate the association of air pollution with the onset of atrial fibrillation (AF).

Background: Air pollution in general and more specifically particulate matter has been associated with cardiovascular events. Although ventricular arrhythmias are traditionally thought to convey the increased cardiovascular risk, AF may also contribute.

Methods: Patients with dual chamber implantable cardioverter-defibrillators (ICDs) were enrolled and followed prospectively. The association of AF onset with air quality including ambient particulate matter <2.5 μm aerodynamic diameter (PM2.5), black carbon, sulfate, particle number, NO2, SO2, and O3 in the 24 h prior to the arrhythmia was examined utilizing a case-crossover analysis. In sensitivity analyses, associations with air pollution between 2 and 48 h prior to the AF were examined.

Results: Of 176 patients followed for an average of 1.9 years, 49 patients had 328 episodes of AF lasting ≥ 30 s. Positive but nonsignificant associations were found for PM2.5 in the prior 24 h, but stronger associations were found with shorter exposure windows. The odds of AF increased by 26% (95% confidence interval: 8% to 47%) for each 6.0 μg/m(3) increase in PM2.5 in the 2 h prior to the event (p = 0.004). The odds of AF were highest at the upper quartile of mean PM2.5.

Conclusions: PM was associated with increased odds of AF onset within hours following exposure in patients with known cardiac disease. Air pollution is an acute trigger of AF, likely contributing to the pollution-associated adverse cardiac outcomes observed in epidemiological studies.

Keywords: AF; BC; CI; EPA; Environmental Protection Agency; ICD; PM(2.5); PNC; air pollution; atrial fibrillation; black carbon; confidence interval; implantable cardioverter-defibrillator; particle number count; particulate matter; particulate matter <2.5 μm aerodynamic diameter; traffic.

Figure 1. Electrocardiogram of atrial fibrillation

Intracardiac electrogram documenting the initiation of a disorganized atrial arrhythmia. Note the defibrillator documented time and date of arrhythmia onset as well as the intracardiac electrogram of both the atrium and the ventricle. The rapid and irregular atrial rate is typical of atrial fibrillation.

Figure 2. Risk of atrial fibrillation with air pollution

Percent increase in the occurrence (odds) of AF episodes associated with increase in air pollution (PM_2.5, black carbon, and NO₂) as a function of moving average in hours prior to event. Stronger increased odds were found with shorter exposure periods before the AF event with the strongest odds in the 2 hour moving average.

Figure 3. Risks of atrial fibrillation relative to quartile of pollution in the 2 hours prior to the arrhythmia

This figure models the predictors as quartiles and plots each quartile at the median concentration for that quartile. Percent increased occurrence (odds) of AF for 2-hour moving averages of air pollution (PM_2.5, black carbon and NO₂) versus quartile medians. There was an apparent exposure response effect in that the highest risk of AF was in the highest quartile of PM_2.5.

Figure 4. Risk of atrial fibrillation with air pollution in patients living within 26 km of the air pollution monitoring site

In analyses restricted to the 25 patients (174 AF events) living closer than 26 km from the air pollution monitoring site, a stronger association was found with air pollution in the prior 2 hours for PM_2.5 (42% increased odds compared to 26% in the whole population), BC (22% increased odds compared to 16% in the whole population), NO₂ (28% increased odds compared to 18% in the whole population).

Figure 5. Risk of atrial fibrillation with air pollution in patients without a prior history of atrial fibrillation

In analysis restricted to the 25 subjects with no history of AF prior to study enrollment (124 episodes of AF) the associations with PM_2.5 and BC were similar and stronger for NO₂ compared to all patients.