SATURDAY, March 29 (HealthDay News) -- The anniversary of the death of a parent can trigger sudden death -- especially in men -- according to research to be presented over the weekend at the American College of Cardiology's annual meeting in Chicago.

Sudden death, usually caused by lethal arrhythmia (irregular heartbeat), occurs unexpectedly and often within one hour of the onset of symptoms, the researchers found.

"We've all known close family members who have died within hours, weeks, months or years of each other," said the lead investigator of the study, Dr. Ivan Mendoza from Central University of Venezuela in Caracas.

"Physicians should be aware that mental stress, such as the anniversary effect, may induce sudden death in susceptible individuals," he added in a prepared statement.

Researchers evaluated a series of 102 documented sudden deaths of individuals between 37 and 79 years old, 70 percent of whom died with coronary artery disease, the study found.

In 12 percent of the cases, the death occurred on the anniversary date of the death of a parent: seven occurred on the father's; five on the mother's, one on the anniversary of both when they died on the same date.

Roughly one-third died at a similar age as the parent, the study showed.

And almost 80 percent of those who died suddenly under the anniversary effect were male.

The reason for this is not understood, but may reflect gender differences in response to stressful situations, said co-investigator Dr. Juan Marques, also from the university.

According to Mendoza, patients may be especially vulnerable if they have a history of heart attack, family history of sudden death or coronary disease, and cardiovascular risk factors such as high cholesterol, high blood pressure, diabetes, smoking, obesity or a sedentary lifestyle.

More information

To learn more about sudden cardiac death, visit the American Heart Association.