In the 60 days after the terrorist attacks, New York Methodist Hospital in Brooklyn treated 35 percent more heart attacks and 40 percent more tachyarrhythmias (irregular heart beats) than in the 60 days before the attacks, said Jianwei Feng, M.D., lead author of the study. Feng is now a cardiology fellow at the University of Texas Health Science Center in Houston.
Because psychological stress increases stress hormones, people with heart disease face greater risks of serious cardiac events during emotional stress, he said. Heart attacks and cardiac arrhythmias are both related to a surge in stress hormones known as catecholamines, which stimulate nerve chemicals.
"Anytime a person experiences psychological or emotional stress, catecholamine levels rise, which increases heart rate and blood pressure," he said.
The risks associated with psychological or emotional trauma have potentially major implications for people with heart diseases and risk factors, such as high blood pressure and diabetes.
"Drugs that help control catecholamines, such as beta blockers, may reduce the risk in patients with cardiac disease and cardiac risk factors," Feng said.
When the New York terrorist attacks occurred, Feng was a resident at New York Methodist Hospital, located about four miles from the World Trade Center's twin towers. The day after the attacks, Feng admitted a middle-aged man complaining of chest pain and shortness of breath.
"The man told me that he was about a block away from the Twin Towers when the attack occurred," Feng said. "Initially, he was OK, but the more he watched the TV reports about the attack, the more upset he became. He began to have heart palpitations and shortness of breath."
Feng discussed the patient with cardiology chief C. V. R. Reddy, M.D., which prompted researchers to study the link between psychological stress and cardiac events.
Investigators identified 425 patients who had been evaluated at the Brooklyn hospital for a possible heart attack or heart rhythm disturbance during the 60 days after the terrorist attacks. For comparison, they evaluated medical records of 428 patients evaluated for heart attack and cardiac arrhythmias in the two months before Sept. 11, 2001.
Before the terrorist attack date, 11.2 percent of the patients had a heart attack. After the terrorist attack date, 15.3 percent had diagnosed heart attacks, a 35 percent increase. The proportion of patients diagnosed with cardiac arrhythmias increased from 13.3 percent before the terrorist attack to 18.8 percent afterward - a 40 percent increase.
In contrast, the proportion of patients with unstable angina (chest pain) decreased from 47.2 percent before Sept. 11, 2001, to 39.3 percent in the 60 days afterward.
"Our hypothesis is that the rate of unstable angina was lower because more patients with unstable angina progressed to acute heart attacks and acute cardiac arrhythmias," Feng said.
Researchers examined medical records for patients who received emergency cardiac evaluations during the same period in 2000. They found no differences in acute heart attack, cardiac arrhythmias, or unstable angina.
The findings have sparked interest in exploring other possible adverse heart effects related to the psychological trauma of the terrorist attacks.
Feng plans to extend the study to patients who have heart pacemakers or implantable cardioverter-defibrillators (ICD) - implanted devices delivering electric shocks to the heart to correct rhythm disturbances.
"A computer can be used to check an ICD to see how many shocks occurred before, during and after Sept. 11," Feng explained. "We can evaluate ICD activity over a two- or three-month period to determine the type of shocks and the severity of the arrhythmias."
The findings corroborate those of a study reported at Scientific Sessions 2002 in which researchers at another New York hospital reported that the rate of serious heart rhythm disturbances doubled during the 30 days after the September 11 terrorist attacks.
Co-authors are Vandana Karri and C.V. R. Reddy.