The study evaluated patients with an implantable cardioverter-defibrillator (ICD). An ICD is an electrical generator the size of a pocket watch that is inserted into the heart to monitor heart rhythm. It detects life-threatening abnormal rhythms, called arrhythmias, and delivers an electrical shock to restore normal rhythm.
Beginning a few days after the terrorist attack on the World Trade Center, the rate of ICD discharges increased and remained elevated throughout the next month.
Researchers evaluated 200 patients (average age 69) with ICDs at six clinics within 100 miles of the World Trade Center. The devices had been implanted an average of 2.5 years before the terrorist attack.
ICDs can store monitoring data, allowing comparison of rhythm patterns and shock rates from different times. The researchers compared ICD discharge rates for the 30 days before and after the terrorist attack. In the month before the attack, 3.5 percent (seven patients) had heart rhythm disturbances that required electrical shocks from their ICDs. In the 30 days after the attack, 8 percent (16 patients) did a 2.3-fold increase.
The results provide compelling evidence of the impact of stress on the heart, says Marcin Kowalski, M.D., a resident at St. Luke's-Roosevelt Hospital Center in New York. Even more important, the findings demonstrate the life-saving value of ICDs, he says.
"These patients all had potentially lethal arrhythmias in the 30 days after the attack, and they were all successfully treated by ICDs," Kowalski says. "This is just another example showing that patients really benefit from ICDs and that ICDs can help save lives."