Controlled exposure study of air pollution and T-wave alternans in volunteers without cardiovascular disease

Epidemiological studies have assessed T-wave alternans (TWA) as a possible mechanism of cardiac arrhythmias related to air pollution in high-risk subjects and have reported associations with increased TWA magnitude. In this controlled human exposure study, the authors assessed the impact of exposure to concentrated ambient particulate matter (CAP) and ozone (O3) on T-wave alternans in resting volunteers without pre-existing cardiovascular disease. Seventeen participants without pre-existing cardiovascular disease were randomised to filtered air (FA), CAP (150 íg/m3), O3 (120 ppb), or combined CAP + O3 exposures for 2 hours. Continuous electrocardiograms (ECGs) were recorded at rest and T-wave alternans (TWA) was computed by modified moving average analysis with QRS alignment for the artefact-free intervals of 20 beats along the V2 and V5 leads. Exposure-induced changes in the highest TWA magnitude (TWAMax) were estimated for the first and last 5 min of each exposure (TWAMax-Early and TWAMax-Late respectively). ¢TWAMax (Late-Early) were compared among exposure groups using analysis of variance. Mean (SD values for ¢TWAMax were -2.1 ( 0.4, -2.7 ( 1.1, -1.9 ( 1.5, and -1.2 ( 1.5 in FA, CAP, O3, and CAP + O3 exposure groups, respectively. No significant differences were observed between pollutant exposures and FA. the authors concluded that the findings from the study did not show any significant changes in T-wave alternans after 2-h exposures to CAP, O3, or combined CAP + O3. This finding, however, does not preclude the possibility of pollution-related effects on TWA at elevated heart rates, such as during exercise, or the possibility of delayed responses.

Authors: Kusha, Marjan; Masse, Stephane; Farid, Talha; Urch, Bruce; Silverman, Frances; Brook, Robert D.; Gold, Diane R.; Mangat, Iqwal; Speck, Mary; Nair, Krishnakumar; Poku, Kwaku; Meyer, Chris; Mittleman, Murray A.; Wellenius, Gregory A.; Nanthakumar, Kumaraswamy ;Full Source: Environmental Health Perspectives 2012, 120(8), 1157-1161 (Eng) ;