The purpose of this study is to more accurately identify people who are at risk for developing complications of coronary artery disease, particularly life-threatening heart rhythm disturbances. There are currently no simple and effective screening tools or guidelines to access the risk of sudden cardiac death in patients with coronary artery disease who do not have severe heart muscle weakness. By examining participants current medical history, cardiac tests, medications, lifestyle habits, genes and other biologic markers (such as proteins and fats) found in blood, we may be able to predict who is most at risk for life-threatening abnormal heart rhythms. We hope to improve our ability to identify people who are at an elevated risk of dying suddenly from these heart rhythms. Early identification of those at risk may then allow us to intervene and prevent sudden cardiac death. We also hope to advance knowledge regarding potential underlying causes of sudden cardiac death, which eventually could lead to new therapies.
Sudden Cardiac Arrest (SCA) and sudden cardiac death (SCD) are major health problems, claiming over 400,000 lives every year in the United States. SCA accounts for approximately 19% of all deaths in the United States. Some SCA victims may not know that they are at risk of SCD right up to the moment when SCA strikes.
SCA results from a disturbance in the normal electrical activation of the heart.  During a SCA, abnormal rapid and chaotic heartbeats arise from the bottom chamber of the heart at rates as high as 400 beats per minute. This chaotic heart rhythm overrides the normal coordinated contraction of the heart, which averages 60-100 beats per minute.  When this happens, the heart can no longer effectively pump blood and oxygen to the brain and rest of the body.  The brain and body cannot survive more than a few minutes without oxygen, and the person dies from SCD if emergency medical assistance cannot restore normal electrical activity within a very short time span.  In approximately 94-95% of cases, SCA is fatal leading to (SCD).  SCA can sometimes occur during a heart attack; however, it is not the same as a heart attack.  A heart attack is caused by a blocked artery leading to loss of blood supply to a portion of the heart muscle, which does not always lead to abnormal electrical activation of the heart and SCA.  However, people who have had a previous heart attack have a 4-6 times higher risk of SCA than the general population. In people diagnosed with congestive heart failure (CHF; a decrease in the pumping of the heart), SCA occurs at 6-9 times the rate of the general population. In approximately 94-95% of cases, SCA is fatal leading to sudden cardiac death.
Participants were enrolled at participating clinical cardiology sites, where information on demographic, clinical characteristics, pertinent past medical history, lifestyle habits, and medications were collected. The most recent 12-lead electrocardiogram (EKG) performed for clinical evaluation and a blood sample (approximately 4 teaspoons) were collected at this visit and sent to a central laboratory to be stored for future analysis. Enrolled participants are asked to reply to a brief health questionnaire from Brigham and Women’s Hospital in Boston, Massachusetts every 6 months, which inquires about recent medical diagnoses and hospitalizations pertaining to life-threatening heart rhythm disturbances, as well as provide permission to release medical records about recent medical diagnoses and hospitalizations in regard to life-threatening heart rhythm disturbances.