op
RESEARCH STUDY EVALUATING THE ROLE OF PACEMAKERS

• Sick Sinus Syndrome
• What Is A Pacemaker?
• Single Versus Dual Chamber Pacemaker: Which Is Better For You?
• The MOST Trial

Sick Sinus Syndrome (SSS) is a condition affecting individuals with structural heart disease, more commonly occurring in individuals over 65 years old. SSS affects the ability of the heart to generate a heart beat. Consequently, the heart may slow down, or "pause", for periods of several seconds at a time. When this happens, a fainting spell may occur and an individual can fall or injure him/herself. Pacemakers are widely used to correct this electrical rhythm disturbance of the heart.

A permanent pacemaker is a small electronic device (about the size of a box of paper clips), which is implanted under the skin (usually below the collar bone), and programmed to generate and regulate the heart beat. One or two wires or "leads" are placed within the heart and connected to the generator. We usually implant permanent pacemakers in the cardiac catheterization laboratory.

Currently in the United States, approximately one third of patients who have SSS, receive a dual-chamber pacemaker (two leads, one in the right upper and one in the right lower chambers of the heart). The other two thirds have single-chamber pacemakers (one lead inside the right lower chamber alone). Single-chamber pacemakers are simpler, cost a little less, and tend to last a few years longer. Dual -chamber pacemakers are a little more difficult to put in, cost a little more, and have a slightly shorter battery life. However, they allow the heart a more normal function. There is still a controversy among cardiologists as to which kind of pacemaker is better for patients with SSS.

The purpose of this study is to determine whether or not the dual -chamber pacemaker, even though it is more expensive and has a shorter battery life, is better for patients with Sick Sinus Syndrome. Patients who present with SSS will be randomized to either mode and will be followed for two to five years. Quality of life will also be closely monitored. The long-term results of this trial will help define the optimal treatment for this important subset of patients. Sponsor: Mount Sinai / Duke Clinical Research Institute, 1997 to present.