Clinical Science

Pre-existing cardiovascular disease and susceptibility to particulate air pollution: In post-MI patients, particle exposures are associated with decreased heart rate variability, indicating an autonomic response (Wheeler, Zanobetti et al. 2006). These particle-HRV effects were modified by beta-blocker, bronchodilator intake (Wheeler, Zanobetti et al. 2006), and genetics (Chahine, Baccarelli et al. 2007). Cardiac patients with implanted cardioverter defibrillators (ICD) had increased risk of ventricular arrhythmias following episodes of elevated ambient PM2.5 concentrations (Dockery, Luttmann-Gibson et al. 2005; Rich, Schwartz et al. 2005). There was suggestive evidence that air pollution episodes may precipitate paroxysmal atrial fibrillation episodes (PAF) that result in rapid ventricular rates (Rich, Mittleman et al. 2006). Corresponding studies in awake, alert canine models with implanted monitoring devices (Bartoli et al 2008, Godleski 2006) examine coronary artery perfusion with concentrated ambient particle exposure.

Diabetes and susceptibility to particulate air pollution: Diabetics exposed to increases in ambient particles showed changes in reactive hyperemia and increased arrhythmias ((Peters, Liu et al. 2000; Rich, Kim et al. 2006)(Zanobetti, Schwartz et al. 2002; Dubowsky, Suh et al. 2006; Sarnat, Suh et al. 2006). Diabetics had decreased vascular reactivity associated with ambient particles (O'Neill, Veves et al. 2005) but no association was found in patients at risk but without a diagnosis of diabetes. Among patients with type 2 diabetes, plasma levels of soluble ICAM-1; VCAM-1; and vWF were associated with ambient particle exposures (O'Neill, Veves et al. 2007). Particle associations with VCAM-1 were particularly strong among those not taking statins. These results indicate inflammatory mechanisms may explain the increased risk of air pollution-associated cardiovascular events among those with diabetes.