Academic journal article Environmental Health Perspectives

Triggering of Transmural Infarctions, but Not Nontransmural Infarctions, by Ambient Fine Particles

Academic journal article Environmental Health Perspectives

Triggering of Transmural Infarctions, but Not Nontransmural Infarctions, by Ambient Fine Particles

Article excerpt

BACKGROUND: Previous studies have reported increased risk of myocardial infarction (MI) after increases in ambient particulate matter (PM) air pollution concentrations in the hours and days before MI onset.

OBJECTIVES: We hypothesized that acute increases in fine PM with aerodynamic diameter [less than or equal to] 2.5 [micro]m ([PM.sub.2.5]) may be associated with increased risk of MI and that chronic obstructive pulmonary disease (COPD) and diabetes may increase susceptibility to [PM.sub.2.5]. We also explored whether both transmural and nontransmural infarctions were acutely associated with ambient [PM.sub.2.5] concentrations.

METHODS: We studied all hospital admissions from 2004 through 2006 for first acute MI of adult residents of New Jersey who lived within 10 km of a [PM.sub.2.5] monitoring site (n = 5,864), as well as ambient measurements of [PM.sub.2.5], nitrogen dioxide, sulfur dioxide, carbon monoxide, and ozone.

RESULTS: Using a time-stratified case-crossover design and conditional logistic regression showed that each interquartile-range increase in [PM.sub.2.5] concentration (10.8 [micro]g/[m.sup.3]) in the 24 hr before arriving at the emergency department for MI was not associated with MI overall but was associated with an increased relative risk of a transmural infarction. We found no association between the same increase in [PM.sub.2.5] and nontransmural infarction. Further, subjects with COPD appeared to be particularly susceptible, but those with diabetes were not.

CONCLUSIONS: This PM--transmural infarction association is consistent with earlier studies of PM and MI. The lack of association with nontransmural infarction suggests that future studies that investigate the triggering of MI by ambient [PM.sub.2.5] concentrations should be stratified by infarction type.

KEY WORDS: air pollution, epidemiology, myocardial infarction. Environ Health Perspect 118:1229-1234 (2010). doi:10.1289/ehp.090l624 [Online 30 April 2010]

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Most previous studies (D'Ippoliti et al. 2003; Peters et al. 2001, 2005; Pope et al. 2006; Zanobetti and Schwartz 2005), but not all (Sullivan et al. 2005), that have investigated the triggering of myocardial infarction (MI) by particulate matter (PM) air pollution concentrations in the hours and days before MI onset have reported an association. Other studies have reported increased mortality due to MI or increased mortality or cardiovascular admissions among MI survivors associated with increases in PM over the previous few days (Braga et al. 2001; von Klot et al. 2005; Zanobetti and Schwartz 2007). Several studies have investigated whether certain subgroups are particularly susceptible and have reported increased cardiovascular effects among those with diabetes (Dubowsky et al. 2006; Goldberg et al. 2001; Liu et al. 2007; O'Neill et al. 2005; Zanobetti and Schwartz 2002) and among patients with chronic obstructive pulmonary disease (COPD) (Naess et al. 2007; Zanobetti and Schwartz 2005; Zanobetti et al. 2000). However, Zanobetti and Schwartz (2005) reported increased susceptibility among patients with COPD but not among persons with diabetes.

Numerous researchers have reported that the percentage of infarctions that are nontransmural has been increasing (Goff et al. 2000; Hellermann et al. 2003; Kostis et al. 2007; Myerson et al. 2009; Roger et al. 2006, 2010; Rogers et al. 2008). More recently, Shao (2008) noted a similar secular trend in clinical presentation of MI to emergency departments (EDs) in New Jersey. In short, 72% of persons admitted to hospitals in New Jersey from 1990 through 1992 for MI had had transmural infarctions, and only 28% had had nontransmural infarctions. Since then, however, this pattern has reversed. From 2002 through 2004, most of the admissions for MI were for nontransmural infarctions (63%), with only 37% for transmural infarctions (Shao 2008). These changes may be due in part to improvements in preventive pharmacotherapies (statins, beta blockers, aspirin), interventional procedures [angioplasty, coronary artery bypass graft (CABG)], more sensitive diagnostic tests (troponins), and treatment of the MI upon ED arrival (reperfusion therapy, increased use of antiplatelet agents). …

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