Heart Rate Variability (HRV) to Evaluate Surgical Risk on Patients on Beta Blockers

Study Overview
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Brief Summary
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Beta blockers have been shown to decrease the risk of intraoperative cardiac events in patients at high cardiac risk. However, they have also been associated with side effects (for instance, stroke.) The role of beta blockers in patients at intermediate cardiac risk undergoing surgery is controversial. Heart rate variability is a way of evaluating the cardiac function of a patient. Decreased heart rate variability is associated with early cardiac death in patients with congestive heart failure (CHF) and after a heart attack. It has been shown to transiently decrease in patients in hemorrhagic shock after trauma and returns to normal after resuscitation in trauma and burn patients. The investigators hypothesize that beta blockers will maintain pre operative heart rate variability in patients with intermediate risk of cardiac events during operative intervention with laparoscopic surgery.

Official Title
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Using Heart Rate Variability to Analyze the Effect of Beta Blockers on Intermediate Risk Patients Undergoing Laparoscopic Surgical Procedures

Conditions
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Cardiac Event Risk

Intervention / Treatment
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* Drug: metoprolol


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age 40-75 years old intermediate risk of adverse cardiac events: renal insufficiency (CrCl < 60) diabetes mellitus two of the following: age > 50 obesity hypertension hyperlipidemia hypercholesterolemia prior stroke undergoing an elective laparoscopic abdominal surgery less than three hours: cholecystectomy ventral hernia repair umbilical hernia repair gastric bypass or gastric banding Exclusion Criteria: currently taking a beta blocker prior heart attack rhythm other than sinus on ECG contraindication to beta blockers: decompensated CHF severe valvular disease asthma COPD hypersensitivity to beta blockers heart rate < 60 currently taking a calcium channel blocker urgent or emergent surgery

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Beta blocker<br>These patients will be randomized to receive a standard dose of metoprolol (50mg) starting two weeks prior to surgery | Drug: metoprolol<br>* 50mg PO BID starting two weeks prior to surgery. Patients will be reevaluated one week prior to surgery. If their pulse is above 70, the dose will be increased to 100mg BID. If the HR is 50-70, the dose will not be changed. If the pulse is below 50, the dose will be decreased to 25mg. This dose will be continued for thirty days after operation.<br>|
| No Intervention: Control<br>This arm will receive no additional treatment prior to surgery | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart Rate Variability |  | 2 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Intermediate risk of adverse cardiac event, Undergoing laparoscopic surgical procedure, Age forty to seventy five