Effectiveness of an Exercise Program at Improving Heart and Lung Function in People With an Implantable Cardioverter Defibrillator (ICD)

An ICD is a device designed to quickly detect a life-threatening, rapid heartbeat. Through a
process called defibrillation, the ICD tries to convert an abnormal heart rhythm back to
normal by delivering an electrical shock to the heart. The ICD continuously monitors
heartbeats to ensure that they are normal, and it only delivers a shock to the heart when it
senses a life-threatening rhythm. People who have experienced ventricular fibrillation,
which is a severely abnormal heart rhythm, or ventricular tachycardia, which is a rapid
heart beat that begins in the bottom chambers of the heart, are common recipients of an ICD.
Other potential ICD recipients include people who have survived a heart attack, but have
weak hearts; people with heart muscle problems; and people with reduced pumping function in
their heart. People who have ICDs may benefit from aerobic exercise to improve their
physical fitness and overall health. The purpose of this study is to evaluate the
effectiveness of an exercise program at improving heart and lung function in people who have
an ICD.

In this 6-month study, participants will be randomly assigned to either take part in the
exercise program or receive usual care. At a baseline study visit, all participants will
complete an exercise treadmill test, wear a Holter monitor to record heart activity for 24
hours, undergo blood collection, and complete questionnaires to assess quality of life,
anxiety, and depression. Participants taking part in the exercise program will receive 1
hour of exercise education over the telephone. During Weeks 1 through 8, participants will
stretch for 10 minutes and walk 1 hour daily for 5 days a week; during Weeks 9 through 24,
participants will walk 30 minutes daily for 5 days a week. Participants will wear a Polar
Heart Rate monitor to record their heart rate and a pedometer to keep track of the number of
steps walked. They will also record details of their exercise in a daily activity log.
Throughout the entire study, a study nurse will call participants on a weekly basis to check
on their progress and to help resolve any exercise-related problems. At Weeks 8 and 24, all
participants including those receiving usual care, will attend a study visit for repeat
baseline evaluations. Study researchers will review medical records to collect various
information, including the reason for needing an ICD, the type and settings of the ICD,
medication use, medical history, current health problems, lab test results, echocardiogram
images of the heart, and electrocardiogram (EKG) results.

Inclusion Criteria:

- ICD implanted in the 12 months prior to study entry

- Currently taking beta blocker medication

- Speaks and reads English

Exclusion Criteria:

- Unstable angina, heart attack, or percutaneous coronary intervention (PCI) in the 3
months prior to study entry

- Experienced an ICD shock in the 3 months prior to study entry

- Currently exercises 3 times a week for 20 minutes a day

- Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) score for alcohol
consumption greater than 4

- Shore Blessed score for cognitive dysfunction greater than 6