Implanted cardioverter-defibrillators (ICDs) improve the survival rates of patients with chronic heart disease by 30 percent to 54 percent. However, they also appear to increase the risk of heart failure.
ICDs are recommended for patients who have had a fatal episode of arrhythmia or abnormal heart rhythm. The devices are designed to detect arrhythmias, where the heart beats too slowly or too rapidly, and to deliver a small electrical shock to restore normal rhythm.
Researchers from the University of Rochester Medical Center in New York, USA, reviewed the records of 1,197 patients who had an ICD. They analysed the factors associated with the progression to heart failure. The patients had experienced a heart attack at least one month before the implantation of ICD and had a deteriorated ability to pump blood from the heart.
It was found that the rate of hospitalisation for heart failure was higher among those with single chamber ICDs (22 percent) and dual-chamber ICDs (25 percent) compared with patients in the conventional drug therapy group (17 percent). Nevertheless, survival was increased by the ICDs, and was similar before and after a first heart failure event in patients who received the single-chamber ICD group. However, those who received the dual-chamber ICD had significantly worse survival rates after a heart failure event.
Prevention of heart failure progression is vital after ICD implantation. One way to achieve this is through cardiac resynchronisation therapy, along with drug therapy that includes a beta-blocker.
Circulation,
June 2006
June 2006