In patients with heart failure and in those with a history of sudden cardiac death, an Implantable Cardiac Defibrillator (ICD) reduces death rates. However, not all patients with an ICD receive appropriate therapy from it. Inappropriate ICD shocks are common and are associated with worse quality of life and increased death rate. We hope to establish a better predictor of risk of sudden cardiac death and of response to ICD. We are conducting a prospective observational study of 150 patients (18-80 years) with an indication for ICD implantation for primary prevention of sudden cardiac death. Prior to the implantation of a clinically indicated ICD, the heart rate response to regadenoson will be assessed. Regadenoson will be administered intravenously as a fixed intravenous bolus dose of 400 μg followed by a 5 mL saline flush.~The main objectives of this proposal are to investigate whether:~A blunted heart rate response to regadenoson is an independent predictor of sudden cardiac death.~A blunted heart rate response to regadenoson can be used as a predictor of response to ICD on top of traditionally used indicators.~We Hypothesize that:~Patients with a blunted heart rate response to regadenoson are at higher risk of sudden cardiac death (death or appropriate cardiac defibrillation). This risk is maintained after controlling for age, gender, left ventricular ejection fraction, heart failure symptoms and medication use.~Patients with a normal heart rate response to regadenoson have a low rate of events (death or appropriate cardiac defibrillation) despite meeting current indications for having an ICD.
The purpose of this study is to determine whether a blunted heart rate response to regadenoson is an independent predictor of sudden cardiac death.