Arrhythmias and particulate matter
Authors: Jonathan Grigg
Journal: The Lancet Planetary Health (2017)

There is strong epidemiological evidence that inhalation of combustion-derived soot triggers life-threatening cardiovascular events. Indeed, the 2015 Global Burden of Disease estimated that 1 521 000 (35%) of the total of 4 241 000 deaths attributable to ambient particulate matter (PM; all causes) were from ischaemic heart disease.1GBD Risk Factors CollaboratorsGlobal, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015.Lancet. 2016; 388: 1659-1724Summary Full Text Full Text PDF PubMed Scopus (2841) Google Scholar But policy makers continue to regard these mortality figures with scepticism, and delay enacting the urgent interventions that will significantly reduce population exposure to air pollution. For example in the UK, there is no national plan to replace the present highly polluting fleet of diesel cars, vans, and taxis. Potential reasons for this scepticism include difficulty in communicating to non-specialists the methods used to attribute deaths to air pollution,2WHO Regional Office for EuropeHealth and environment: communicating the risks.http://www.euro.who.int/__data/assets/pdf_file/0011/233759/e96930.pdfGoogle Scholar and the absence of experimental data directly linking inhalation of PM to cardiovascular disturbances known to cause fatal events. The study by Franco Folino and colleagues, addresses this latter issue by linking air pollution data from the Vento region of Italy with ventricular arrhythmia data stored by implanted defibrillators. Folino and colleagues report a significant association between episodes of ventricular tachycardia and ventricular fibrillation and PM of less than 2·5 μm in aerodynamic diameter (PM2·5),3Folino F Buja G Zanotto G et al.Association between air pollution and ventricular arrhythmias in high-risk patients (ARIA study): a multicentre longitudinal study.Lancet Planet Health. 2017; 1: e58-e64Summary Full Text Full Text PDF Scopus (34) Google Scholar a result that both strengthens the case for a causal association between PM and cardiovascular deaths, and suggests further innovative studies. First, by adding personal carbonaceous PM monitoring to this group of high-risk patients (figure), it should be possible to determine the independent association between locally generated traffic PM and arrhythmias. Second, contribution of fossil fuel and wood smoke to background PM in the Vento region offers a way of assessing the effect of different types of PM. Indeed, in-vitro toxicity studies suggest that not all particles are equal. For example, wood smoke PM, compared with diesel PM, induces higher levels of oxidative damage to human umbilical endothelial cells and stimulates increased monocyte adhesion.4Forchhammer L Loft S Roursgaard M et al.Expression of adhesion molecules, monocyte interactions and oxidative stress in human endothelial cells exposed to wood smoke and diesel exhaust particulate matter.Toxicol Lett. 2012; 209: 121-128Crossref PubMed Scopus (55) Google Scholar Normally, ambient black carbon from fossil-fuel combustion is measured by an aethalometer using infrared light absorption. However, some of the larger aethalometers also assess ultra-violet light absorption, a spectrum that detects aromatic organic compounds found in wood smoke and other biomass sources. Thus, light absorption from both wavelengths could be used to identify the independent effect of background wood smoke PM on arrhythmias—a result that would be highly relevant to exposures in low-income countries, where wood burning is a major source of personal exposure to carbonaceous PM.5Gordon SB Bruce NG Grigg J et al.Respiratory risks from household air pollution in low and middle income countries.Lancet Respir Med. 2014; 2: 823-860Summary Full Text Full Text PDF PubMed Scopus (546) Google Scholar What should clinicians tell high-risk cardiovascular patients about air pollution? To date, management guidelines provide little or no guidance. A recent workshop hosted by the European Respiratory Society addressed this question and identified two major areas that should be considered by future guidelines.6Powell P Brunekreef B Grigg J How do you explain the risk of air pollution to your patients?.Breathe (Sheff). 2016; 12: 201-203Crossref PubMed Scopus (9) Google Scholar First, patients should understand how acute episodes of poor air quality will affect their own health, and the actions they need to take to protect themselves. Second, health-care providers need the tools to advise patients about air pollution and how to change their treatment plans or activities on high pollution days, and how to reduce long-term exposure.6Powell P Brunekreef B Grigg J How do you explain the risk of air pollution to your patients?.Breathe (Sheff). 2016; 12: 201-203Crossref PubMed Scopus (9) Google Scholar In some cities, patients are able to sign up to text message services that warn about pollution and provide advice about how to reduce short-term risk. For example, London's airText's advice to adults with heart problems on very high pollution days is to "avoid strenuous physical activity".7airTextPollution index and health advice.http://www.airtext.info/healthGoogle Scholar It remains unclear, however, whether this, albeit sensible, advice reduces the daily dose of particles inhaled into the lungs. Use of a facemask on high pollution days is another option that patients are increasingly asking clinicians about. Facemasks are socially acceptable in countries such as China, and are widely used by urban cyclists in many other countries. Preliminary evidence for the efficacy of facemasks was provided by a randomised crossover trial8Langrish JP Li X Wang S et al.Reducing personal exposure to particulate air pollution improves cardiovascular health in patients with coronary heart disease.Environ Health Perspect. 2012; 120: 367-372Crossref PubMed Scopus (214) Google Scholar of patients with coronary heart disease who walked a predefined route in central Beijing, China, with and without a facemask. The study found that the facemask was well tolerated, reduced maximal ST segment depression, and increased heart rate variability.8Langrish JP Li X Wang S et al.Reducing personal exposure to particulate air pollution improves cardiovascular health in patients with coronary heart disease.Environ Health Perspect. 2012; 120: 367-372Crossref PubMed Scopus (214) Google Scholar Avoidance of pollution hotspots from local road traffic is a possible way of reducing long-term exposure. The UK charity Global Action Plan combined short-term and long-term advice in its patient information pack.9Global Action PlanAir quality.https://www.globalactionplan.org.uk/Pages/Category/air-qualityGoogle Scholar The pack includes a map of local high-pollution streets, and recommends regular use of less polluted routes (using the map), travel outside the rush hour, and regular checking of the daily air pollution forecast. In summary, we urgently need more evidence to identify the most effective personal exposure reduction strategies. In developing this evidence, clinicians should not forget to continue to challenge governments to implement national policies that significantly reduce air pollution. Jonathan Grigg is part-funded by the NIHR North Thames Collaboration of Leadership in Applied Health Research and Care. Association between air pollution and ventricular arrhythmias in high-risk patients (ARIA study): a multicentre longitudinal studyParticulate matter has acute pro-arrhythmic effects in a population of high-risk patients, which increase on exposure to fine particles and in patients who have experienced a previous myocardial infarction. The time sequence of the arrhythmic events suggests there is an underlying neurally mediated mechanism. From a clinical point of view, the results of our study should encourage physicians to also consider environmental risk when addressing the prevention of arrhythmic events, particularly in patients with coronary heart disease, advising them to avoid exposure to high levels of fine particulate matter. Full-Text PDF Open Access