NEW YORK (Reuters Health) - Patients with heart rhythm disturbances who have an implantable heart defibrillator are particularly vulnerable to air pollution, a Swedish study indicates.
In patients with these devices, known as implantable cardioverter defibrillators, or ICDs, exposure to air pollution may rapidly (within 2 hours) prompt ventricular arrhythmia -- a potentially life-threatening condition in which the heart rhythm becomes irregular, the study shows.
Previous studies have documented an association of ventricular arrhythmias with air pollution exposure lasting from 24 to 48 hours.
To better understand how rapidly such events might take place, the Swedish team observed 211 patients with ICDs for an average of 33 months.
ICD records of arrhythmia events were analyzed in association with air pollution data from each urban area.
According to the investigators, 73 patients had 114 ventricular arrhythmias during the study period. Ventricular tachyarrhythmias -- a specific type of rapid abnormal heart rhythm - were most common.
In analyzing the data, the researchers found that the risk of arrhythmia was associated with increased levels of air pollution in the preceding 2-hour exposure period, as well as the 24-hour exposure period.
"This study," research leader Dr. Petter L. S. Ljungman of Stockholm South Hospital told Reuters Health, "gives further evidence that air pollution disturbs the electrical conduction of the heart and that within two hours of increased exposure to air pollution, individuals with previous ventricular arrhythmias run the risk of new life-threatening arrhythmias."
SOURCE: European Heart Journal, December 2008.