Main air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillators: A systematic review and meta-analysis

Objective: Previous studies of ambient air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillator (ICD) have yielded mixed results, and the association between air pollution and ventricular arrhythmias in these patients remains unclear. This study aimed to assess and quantify the association between exposure to major air pollutants [CO, inhalable particles (PM10), SO2, fine particulate matter (PM2.5), O3, and NO2] and the presence of ventricular arrhythmia in patients with ICD. Methods: The Medline, PubMed, Web of Science, Global Health Library, Virtual Health Library, Population Information Online (POPLINE), and New York Academy of Medicine Grey Literature Report databases were searched to identify studies analyzing the association between ventricular arrhythmias in patients with ICD and the abovementioned main air pollutants. Pooled estimates were generated using a random-effects model or fixed-effects model, according to the value of heterogeneity. Heterogeneity within studies was assessed using Cochran's Q and I2 statistics. Funnel plots, Egger's regression test, and Begg's rank correlation method were used to evaluate publication bias. Sensitivity analyses were also conducted to evaluate the potential sources of heterogeneity. Results: After a detailed screening of 167 studies, seven separate studies were identified. Ventricular arrhythmias in patients with ICD were found to be positively, but not significantly, associated with CO, PM10, SO2, PM2.5, and NO2, with a pooled estimate [odds ratio (OR) associated with each 10 μg/m3 increase in pollutant concentration, except for CO, which was associated with each 1 mg/m3 increase in concentration] of 1.03 [95% confidence interval (CI): 0.92-1.17, P = 0.59] for CO, 1.01 (95%CI: 0.97-1.05, P = 0.55) for PM10, 1.09 (95%CI: 0.95-1.24, P = 0.22) for SO2, 1.07 (95%CI: 0.95-1.21, P = 0.25) for PM2.5, and 1.06 (95%CI: 0.98-1.14, P = 0.16) for NO2. No increased risk of ventricular arrhythmias in patients with ICD was found to be associated with O3 (OR = 1.00; 95%CI: 0.98-1.01, P = 0.56). Conclusions: The results of this study provide little evidence that ambient air pollutants affect the risk of ICD discharges for treating ventricular arrhythmias. Key words: Air pollutants; Ventricular arrhythmia; Implantable cardioverter-defibrillator; Systematic review