Uncontrolled cardiac arrhythmias requiring anti-arrhythmic therapy other than beta blockers or digoxin Calcium channel blockers: verapamil, diltiazem Any cardiac arrhythmia requiring an anti-arrhythmic medication (excluding stable doses of beta-blockers) Contraindications to the use of beta-blockers, like, uncontrolled depression, unstable angina pectoris, uncontrolled heart failure (grade III or IV), hypotension (systolic blood pressure < 100 mmHg), severe asthma or chronic obstructive pulmonary disease (COPD), uncontrolled type I or type II diabetes mellitus (glycosylated hemoglobin [HbA1C] > 8.5 or fasting plasma glucose > 160 mg/dl at screening), symptomatic peripheral arterial disease or Raynaud’s syndrome, untreated pheochromocytoma, current use or past use in the last two years of beta-blockers or calcium channel blockers Clinically significant cardiac arrhythmias including bradyarrhythmias and/or subjects who require anti-arrhythmic therapy (excluding beta blockers or digoxin). Subjects with controlled atrial fibrillation are not excluded. Inability to suspend treatment with anti-hypertensive medication (including but not limited to: diuretics, beta-blockers, angiotensin converting enzyme [ACE] inhibitors, aldosterone antagonists, etc) for 48 hours pre and post each Pexa-Vec administration Patients requiring treatment with one or more beta-blockers (metoprolol, atenolol, propranolol) or calcium channel blockers with atrioventricular (AV)-nodal blocking activity (verapamil, diltiazem); patients being treated with AV nodal blocker (beta-blocker or calcium channel blocker) are allowed if the agent is being used only for correcting hypertension, and if an acceptable alternative is available (for example, transitioning from a drug such as atenolol to Lisinopril or amlodipine) prior to starting treatment on therapy Any cardiac arrhythmia requiring an anti-arrhythmic medication (excluding stable doses of beta-blockers) Patients currently on beta blockers Patients on chronic nitrate therapy or alpha-blockers Unstable cardiac arrhythmias requiring anti-arrhythmic therapy. Patients with arrhythmia under control with anti-arrhythmic therapy such as beta-blockers or digoxin are eligible. Anti-arrhythmia medication other than beta-blockers or digoxin Anti-arrhythmic therapy other than beta blockers or digoxin Concomitant use of these drugs at baseline and for the duration of digoxin administration (if randomized to receive it):\r\n* The calcium channel blockers diltiazem or verapamil\r\n* Cardiac arrhythmic agents (such as quinidine, amiodarone)\r\n* Other cytochrome P450 (P450) inducer/inhibitors\r\n* NOTE: patients already receiving digoxin are also excluded; patients who take calcium carbonate antacids (e.g., Maalox, Tums, Rolaids) or antidiarrheal adsorbents (kaolin and pectin) should avoid taking these at the same time as the digoxin dose Unstable angina, symptomatic congestive heart failure or cardiac arrhythmia requiring anti-arrhythmic therapy (beta-blockers, calcium channel blockers and digoxin are allowed) Cardiac arrhythmias requiring anti-arrhythmic therapy other than beta blockers or digoxin. Patients with third degree or complete heart block are not eligible unless a pacemaker is in place; patients on medications, which alter cardiac conduction, such as digitalis, beta-blockers, or calcium channel blockers, or who have other conduction abnormalities or cardiac dysfunction could be entered at the discretion of the investigators Cardiac arrhythmias requiring anti-arrhythmic therapy; Note: pace makers, beta blockers, or digoxin are permitted Any cardiac arrhythmia requiring an anti-arrhythmic medication (excluding stable doses of beta-blockers) Clinically significant cardiac arrhythmias and/or patients who require anti-arrhythmic therapy (excluding beta blockers or digoxin); patients with controlled atrial fibrillation are not excluded On beta-blocker treatment; if discontinued, patients must have been off beta-blockers for at least 3 months Normotensive individuals not already on beta blockers (may be on other anti hypertensives): SBP =< 140, DBP =< 90 Any patients already on beta-blockers or contraindicated to receive beta-blockers Hypersensitivity to propranolol, or beta-blockers Cardiac disease: Congestive heart failure (CHF) > Class II NYHA; active coronary artery disease (Myocardial infarction [MI] more than 6 months prior to study entry is allowed); or serious cardiac ventricular arrhythmias requiring anti-arrhythmic therapy (beta blockers or digoxin are permitted) Clinically significant cardiac arrhythmias including bradyarrhythmias and/or subjects who require anti-arrhythmic therapy (excluding beta blockers or digoxin). Subjects with controlled atrial fibrillation are not excluded Have cardiac arrhythmias requiring anti-arrhythmic therapy, with the exception of beta blockers or digoxin. Patients on beta blockers Cardiac arrhythmias requiring anti-arrhythmic therapy other than beta blockers or digoxin Any cardiac arrhythmia requiring an anti-arrhythmic medication (excluding stable doses of beta-blockers) Cardiac arrhythmias requiring anti-arrhythmic therapy other than beta blockers or digoxin. Patients with other established indications for ivabradine: stable, symptomatic chronic heart failure (HF) with a left ventricular ejection fraction ? 35% and in sinus rhythm with a resting heart rate (HR) ? 70 bpm, who are taking maximally tolerated doses of beta-blockers or have contraindications to beta-blocker use Use of an investigational drug or beta adrenergic blockers, including metoprolol, sotalol, within 30 days of randomization Patient requires regular use of beta blockers or calcium channel blockers No use of any anti-arrhythmic medication (except for beta-blockers and calcium channel blockers) including intravenous lidocaine, linezolid, ipratropium, or medications with anti-cholinergic potency (including neostigmine, a tricyclic antidepressant or a monoamine oxidase inhibitor) within 2 weeks prior to registration Current treatment with angiotensin converting enzyme (ACE)-inhibitors or beta blockers No other concurrent angiotensin-converting enzyme (ACE) inhibitors, ?-blockers, or digoxin Current use of (1) medications/supplements to control blood pressure (e.g. beta-blockers, nitrates, calcium channel blockers, phosphodiesterase-5 [PGE5] inhibitors) or (2) the use of statins for cholesterol; Use of an investigational drug or beta adrenergic blockers, including metoprolol, sotalol, within 30 days of enrollment Taking medication that may impair PA tolerance or performance (e.g., beta blockers) Daily treatment with thiazides or ?-blockers (exclusion only if < 3 months) Use of angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, diuretics, aldosterone, renin blockers, aspirin, statins, sildenafil (or other PDE5 inhibitors) and non-steroidal antiinflammatory drugs (NSAIDs)