Wildfire smoke may cause spike in CVD events

Smoke from wildfires may trigger heart- and stroke-related events, particularly among seniors, suggests data from the 2015 California wildfire season published in the Journal of the American Heart Association.   

Wildfire smoke has previously been tied to respiratory conditions but so far its association with cardiovascular events has been inconsistent, wrote senior study author Ana G. Rappold, PhD, and colleagues.

To better understand whether there is a connection, the researchers studied approximately 1.2 million emergency room visits in northern and central California during the summer of 2015 and categorized them based on the concentrations of fine particulate matter (PM2.5) in the air that day.

On dense smoke days, Rappold et al. found people age 65 and older were 42 percent more likely to present to the ER with a heart attack and 22 percent more likely to present with ischemic heart disease than on days with no wildfire smoke. The risk of a cerebrovascular event, such as stroke, was also 22 percent higher on dense smoke days—with lesser increases seen on light and medium smoke days.

Some of the conditions were most likely to occur immediately on high-pollution days, while the largest risk increases for other forms of cardiovascular disease had a one- to four-day lag time following a particularly smoky day.

“Acute PM2.5 exposure and the resulting autonomic stimulation, pro‐coagulability, and inflammation all favor the underlying pathophysiology of the cardiovascular disease outcomes observed in this investigation, including cardiac dysrhythmia, ischemic heart disease, heart failure exacerbation, pulmonary embolism, and cerebrovascular events,” Rappold and coauthors wrote.

The researchers said the study’s results could help public health officials and hospital leaders better plan for wildfire season.

“Hospital administrators may find this information helpful for hospital and emergency department surge planning for increased volume, including staffing, bed utilization, and discharge challenges during ongoing wildfires,” they wrote. “Similarly, stroke centers and hospitals with cardiac catheterization capabilities may find these results applicable to surge preparation.”

Rappold and colleagues noted they didn’t stratify their results by race, sex or socioeconomic factors that may modify individuals’ risk levels for cardiovascular events. However, they believe high-risk individuals should be especially careful about exposure to wildfire smoke and evacuate affected areas, or at least limit outdoor activity on smoky days.

“Further study is needed to define patient populations at increased risk for specific events, but these results suggest that patients with vascular and cardiac risk factors would be among the most susceptible, including patients with underlying coronary artery disease, heart failure, peripheral vascular disease, atrial fibrillation, cerebrovascular disease, hypertension and diabetes mellitus,” the authors wrote.