Bradycardia defined as heart rate (HR) < 50 beats per minute (bpm) Atrial fibrillation with a ventricular rate > 100 beats per minute (bpm) on echocardiograph (ECG) at rest Baseline QTc interval > 470 milliseconds (ms), baseline resting bradycardia <45 beats per minute (bpm), or baseline resting tachycardia >100 bpm Active cardiac arrhythmias with rapid ventricular response (defined as heart rate greater than 100 beats/minute) Unacceptable cardiac risk factors defined by any of the following criteria: patients with congenital long QT syndrome, any history of ventricular fibrillation or torsade de pointes, bradycardia defined as heart rate (HR) < 50 beats per minute (bpm), left ventricular ejection fraction < 30% Have a resting heart rate of >100 beats per minute (bpm). Resting heart rate ? 50 bpm Patients with severe bradycardia (heart rate < 40 beats per minute [bpm], hypotension, light-headedness, syncope) Persistent heart rate (HR) < 50 or > 120 beats per minute (bpm) Bradycardia defined as heart rate < 50 beats per minute; patients with a pacemaker and heart rate >= 50 beats per minute are eligible Persistent heart rate (HR) < 50 or > 120 beats per minute (bpm) Bradycardia as indicated by a heart rate of < 45 beats per minute on the screening electrocardiogram (ECG) and on physical examination Subjects who have a heart rate >= 100 beats per minute (bpm) or =< 45 bpm determined by the ECG recorder’s algorithm on the screening ECG Resting heart rate 50-90 bpm Increased corrected QT (QTc) interval (QTc > 470 ms), patients with baseline resting bradycardia < 45 beats per minute (bpm), or baseline resting tachycardia > 100 bpm Have QTc >450 ms or heart rate ?100 bpm or ?45 bpm at screening Presence of poorly controlled atrial fibrillation (ventricular heart rate > 100 beats per minute [bpm]) Bradycardia (in the presence of known cardiovascular disease) as indicated by a heart rate of < 50 beats per minute on the Screening electrocardiogram (ECG) recording. Heart rate <50 bpm during screening. Heart rate 45-100 beats per minute Heart rate > 60 beats per minute (bpm) Patients with severe bradycardia (heart rate < 40 beats per minute [bpm], hypotension, light-headedness, syncope) Pulse >= 60 beat per minute (bpm) Bradycardia defined as heart rate (HR) < 50 beats per minute (bpm); patients with pacemakers are eligible if HR >= 50 bpm Bradycardia defined as heart rate (HR) < 50 beats per minute (bpm); patients with pacemakers are eligible if HR >= 50 bpm Atrial fibrillation with a controlled ventricular rate (uncontrolled [i.e., >110 bpm] ventricular rate is not allowed [determined by an average of three beats in Lead II or 3 representative beats if Lead II is not representative of the overall ECG]) Bradycardia as indicated by a heart rate of < 45 beats per minute on the screening electrocardiogram (ECG) and on physical examination; Patients with symptomatic bradycardia (heart rate < 50 beats per minute [bpm], hypotension, light-headedness, syncope) Resting heart rate less than 60 bpm at time of screening Bradycardia defined as heart rate (HR) < 50 beats per minute (bpm); patients with pacemakers are eligible if HR >= 50 bpm Bradycardia defined as HR< 50 bpm. Patients with pacemakers are eligible if HR ? 50 bpm. Rhythm abnormalities (other than sinus bradycardia with HR < 50 bpm) Patients with a cardiac pacer whose heart rate is set at a fixed rate and patients on concomitant medication that may limit increase in heart rate in response to hypotension Hypotension (systolic blood pressure < 86 mmHg or bradycardia with a heart rate of <50 beats per minute on the ECG., unless pharmaceutically induced and thus reversible (i.e. beta blockers). Heart rate >100 beats per minute. Heart rate <50 beats per minute; Normal sinus rhythm with resting heart rate >= 80 bpm on screening electrocardiogram (EKG) Exhibit American College of Sports Medicine contraindications to exercise which include a resting heart rate of > 120 beats per minute (bpm), blood pressure > 180/100 mmHg or unstable angina Baseline tachycardia, heart rate (HR) > 100 Uncontrolled tachy or bradyarrhythmia or active myocardial ischemia defined as either: atrial fibrillation with rapid ventricular response (heart rate [HR] > 120 beats per minute [bpm]), ventricular tachycardia or nonsustained ventricular tachycardia, supraventricular tachycardia, third degree heart block, any heart rate less than 40 bpm Bradycardia: heart rate < 50 beats per minute (BPM) Heart rate >= 50 beats per minute Pulse ? 60 beats/minute Bradycardia: heart rate < 50 beats per minute (BPM) Bradycardia defined as HR. < 50 bpm Uncontrolled sinus tachycardia (> 120 beats per minute) Heart rate greater than or equal to -105 beats per minute (bpm), or below 45 bpm (one re-screen allowed) Heart rate > 100