Pollutant Exposure May Raise the Risk for CV Hospitalization

Deborah Brauser

February 15, 2016

BOSTON, MA ― Exposure to particulate matter with a diameter less than 10 µm (PM10) may increase CV-related hospitalizations, new research suggests[1].

The study of 6000 hospital records in Brescia, Italy showed that a mean increase of 1 µg/m3 of daily PM10 was linked to increased admissions for     several conditions, including composite CV events, acute heart failure (HF), acute coronary syndromes (ACS), and atrial fibrillation (AF).

In addition, although the European Union (EU) has set a safety threshold of 50 µg/m3 of PM10 averaged daily, CV hospitalizations increased with     exposure to PM10 at levels above and below this threshold.

Overall, "contemporaneously sampled PM10 levels in the ambient air were independently associated with risk of CV hospitalization (regardless of cause),"     write the investigators, led by Dr Muthiah Vaduganathan (Brigham and Women's Hospital, Boston, MA).

"Our data support the concept that 'lower is better' and that there may be no safe level of PM10, since every incremental increase in short-term exposure     increases risk," they add.

The findings were published online February 2, 2016 in the American Journal of Cardiology.

Evaluating Daily Exposure

For the study, investigators evaluated data on CV hospitalizations from September 2004 through September 2007 in a highly industrialized city in Northern     Italy.

"Average daily exposure to PM10 obtained from arithmetic means of air-pollution data were captured by four selected monitoring stations," state the     researchers. They used the daily average of PM10 on admission day (lag 0-day) and the average of the 3 days prior to admission (lag 3-day) to categorize the data.

Of the days evaluated, 36.7% had PM10 measurements higher than the EU safety threshold. The mean lag 0-day level was 40.2 µg/m3 and mean lag     3-day level was 41.3 µg/m3.

Of the 6000 CV admissions (70% men) that occurred during the study period, 54% had a diagnosis of ACS, 23% had acute HF, 14% had AF, and 9% had malignant     ventricular arrhythmia (MVA).

All Levels Risky?

The relative risk (RR) for composite CV event-related hospitalization was 1.003 (95% CI 1.002–1.005) for PM10 lag 0-day (as a continuous function, per 1-µg/m3 increase). The RRs were 1.008 for hospitalization related to AF (95% CI 1.003–1.01), 1.004 for acute HF or MVA (95% CI 1.001–1.008 and     0.999–1.01, respectively), and 1.002 for ACS (95% CI 0.999–1.005).

These hospitalization RRs were repeated in the PM10 lag 3-day measurements for all except acute HF and MVA, both of which had a new RR of 1.002.

There was no significant variance in hospitalizations between exposure that was lower or higher than the EU safety threshold. Age and sex were also not     significant risk factors.

"Increased levels of PM10, even below the current limits set by the EU, were associated with excess risk for admissions for acute CV events," write the     investigators.

They add that the composite CV hospitalization risk they found was higher than past studies have shown and may be because Brescia "is one of the most     polluted European cities," according to the European Environment Agency.

Therefore, further research, "including contemporary pooled data from multiple cities" is now needed, the researchers write.

The authors report no relevant financial relationships.

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