If some patients with heart disease don't take their doctor's advice to quit smoking, they are probably going to get "shocking" reminders.
A study conducted at Washington University School of Medicine in St. Louis found that heart patients who had implanted defibrillators and also smoked were seven times more likely to have the devices jolt their hearts back into normal rhythm than nonsmokers with the devices. When the devices fire, it can feel like a thump or even a strong kick to the chest.
"Eleven percent of cardiovascular deaths are related to smoking, and previous studies have shown that decreasing or quitting smoking is in itself a very effective therapy for patients with heart disease," says J. Mauricio Sanchez, M.D., lead author of the study, which was published in the April 2006 issue of Heart Rhythm.
"But if having heart disease isn't enough to make patients want to stop smoking," continues Sanchez, a cardiology fellow in the cardiovascular division, "the evidence from our study should definitely add a strong argument to quit."
Implantable cardioverter-defibrillators (ICDs) are self-contained units that are placed within the chest to monitor heart rhythms and deliver electrical charges directly to heart muscle to correct abnormal rhythms. Abnormal rhythms can occur without warning, and some can cause death rapidly if no action is taken. A recent study demonstrated that ICDs decreased the risk of death by 23 percent in patients with congestive heart failure.
"ICDs are implanted in patients at high risk for sudden cardiac death," Sanchez says. "The devices shock the heart out of dangerous rhythms within seconds after they detect them. It's like having a little ambulance in your chest."
The study looked at 105 patients at the School of Medicine with heart disease who had ICDs implanted to prevent sudden cardiac death. The patients were followed for an average of two years.
During this time, more than a third of the patients who smoked received an electrical discharge from their ICDs to correct a potentially life-threatening heart rhythm. Former smokers, those who had stopped smoking at least a month before the study began, still had a fairly high occurrence of ICD discharge -- about a quarter of these patients were shocked by the devices. In contrast, among patients who had never smoked, only about 6 percent received an ICD discharge.