In Canada 1 patient in 200 dies within 30 days of an operation. More than half of these deaths are the direct result of a heart related complication. This cause of death happens 4 times more often than in the same people who do not have an operation. We do not have an effective way to stop these heart attacks. Stress causes the heart rate and the blood pressure to go up which causes the heart to work harder and may be the reason for some heart attacks. One group of drugs that stops the heart from working harder and decrease the number of heart related complications are BETA-BLOCKERS. We wish to add another drug, which has been shown to reduce heart rate and blood pressure, will reduce the number of heart attacks after an operation. CLONIDINE has been shown to reduce heart attacks after operations. Since we know it is not a good idea to stop beta-blockers we want to see if giving clonidine as well as a beta-blocker is safe and has the desired effect of decreasing the number of heart attacks. We want to find out how good the combination of these two drugs are at decreasing the number of heart attacks.

Hypothesis: The addition of clonidine to chronic b-blockade will reduce mortality and cardiac morbidity among intermediate-to-high risk patients undergoing non-cardiac surgery.

Inclusion Criteria:

1. Age ≥ 45 years
2. Current use of b-blocker therapy>=30 days prior to surgery
3. Undergoing non-cardiac surgery with an expected length of stay ≥ 48 hours for medical reasons
4. Informed consent
5. Undergoing major vascular surgery (excluding carotid endarterectomy, dialysis shunt, and vein stripping) OR

Meet >= 2of the following criteria:

1. Coronary artery disease
2. Congestive heart failure
3. Stroke or transient ischemic attack
4. Diabetes mellitus requiring oral hypoglycemic or insulin therapy
5. Preoperative renal insufficiency (creatinine clearance below 60 mL/min)
6. Peripheral vascular disease, as defined by any of the following: history of ischemic intermittent claudication or rest pain, history of revascularization procedure to legs, peripheral arterial obstruction of >= 50% luminal diameter
7. Age >=70 years
8. Intermediate-risk surgical procedure: intra-peritoneal, intra-thoracic, carotid endarterectomy, major orthopedic (hip, knee, spine) surgery, radical prostatectomy, or head-and-neck surgery

Exclusion criteria: - if meets any of the following

1. Prior adverse reaction to clonidine or a-2 agonists
2. Current use of Clonidine or a-2 agonists
3. Current congestive heart failure
4. Only b-blocker taken by patient is sotalol
5. Left ventricular ejection fraction <=40%
6. Systolic blood pressure < = 90 mmHg
7. Concomitant life-threatening disease likely to limit life expectancy to <=30 days.
8. Clinically significant aortic stenosis, defined as an aortic valve area <=1.0 cm2 and/or peak trans-valvular pressure gradient >= 25 mmHg