Rationale: Empirical evidence suggests a strong link between exposure to air pollution and heart failure incidence, hospitalisations and mortality, but the biological basis of this remains unclear.

Objective: To determine the relationship between differential air pollution levels and changes in cardiac structure and function in patients with dilated cardiomyopathy.

Methods and Results: We undertook a prospective longitudinal observational cohort study of patients in England with dilated cardiomyopathy (enrollment 2009-2015; n=716, 66% male, 85% Caucasian) and conducted cross sectional analysis at the time of study enrollment. Annual average air pollution exposure estimates for nitrogen dioxide (NO2) and particulate matter with diameter ≤ 2.5µm (PM2.5) at enrolment were assigned to each residential postcode (on average 12 households). The relationship between air pollution and cardiac morphology was assessed using linear regression modelling. Greater ambient exposure to NO2 was associated with higher indexed left ventricular mass (4.3 g/m2 increase per interquartile range (IQR) increase in NO2, 95% CI 1.9 to 7.0 g/m2) and lower left ventricular ejection fraction (-1.5% decrease per IQR increase in NO2, 95% CI -2.7 to -0.2%), independent of age, sex, socio-economic status and clinical covariates. The associations were robust to adjustment for smoking status and geographical clustering by postcode area. The effect of air pollution on left ventricular mass was greatest in women. These effects were specific to NO2 exposure.

Conclusion: Exposure to air pollution is associated with raised left ventricular mass and lower left ventricular ejection fraction, with the strongest effect in women. Whilst epidemiological associations between air pollution and heart failure have been established and supported by pre-clinical studies, our findings provide novel empirical evidence of cardiac remodelling and exposure to air pollution with important clinical and public health implications.