**Intraoperative measures:**

Certain operative practices and techniques have shown to be of some benefit in reducing the incidence of POAF. Off pump surgery may decrease occurrence of AF, even when taking age into account. (42, 43) The anterior fat pad present in the mediastinum is considered to have parasympathetic nerves, which may play a role in initiating POAF. One study showed that preservation of the fat pad was protective but it could not be replicated in other studies. (44,45) Other factors include inducing hypothermia during Cardio Pulmonary Bypass (CPB), using posterior pericardiotomy and Heparin coated CPB circuit etc. (27)

### **Postoperative measures:**

The only postoperative preventative measure may be early reinitiation of beta blockers and ACE-inhibitors. (13) There was a suggestion in a recent study that early statin use post operatively may be beneficial in preventing POAF after cardiac surgery as well. (46)

If AF does occur and is persistent despite the prophylactic measures, treatment should be initiated. There are two general approaches to AF treatment, Rate control or Rhythm control with both being acceptable as to preferred outcomes. (47) Whatever approach is taken, initial efforts need to be made to try and correct any obvious precipitating or co-existent mitigating factors. Meticulous attention needs to be paid to pain control, volume status, electrolyte balance, correcting anemia and hypoxia. Anticoagulation needs to be initiated as well if the AF is persistent for more than 48 hours.

Rhythm control where in AF is converted to sinus rhythm is preferred when the patient is deemed unstable such as if there is hypotension, ongoing ischemia, co-existing heart failure, if pre excitation is suspected or if the patient is very symptomatic. It is also preferred if anticoagulation is not an option for any reason. Rhythm control can be achieved either with pharmacological cardioversion or electrical cardioversion. Various anti arrhythmic agents can be used to convert AF, Amiodarone is typically preferred, because it can be transitioned to oral route, has comparatively lower proarrhythmic potential and may be better at ventricular rate control. Also as most patients have some underlying left ventricular dysfunction or coronary artery disease, Amiodarone is a safer choice in such patients. It is usually given as an initial bolus at 5 mg/Kg body weight over 30 minutes and then continued as an infusion at a dose of 25 mg /Hr. Various other pharmacological rhythm control agents used include Disopyramide, Procainamide, Flecainide, Ibutilide and Dofetilide. (10)

Direct current (DC) cardioversion is a quick and safe way to attempt rhythm control. Initial shock is attempted at 100 - 200 joules with synchronization when monophasic waveforms are used and 50 – 100 joules when biphasic waveforms are used. As usually the POAF has been present only for a short time DC cardioversion can successfully convert the AF to sinus in up to 95% of the cases. If it is not successful, intra venous Ibutilide can be given before repeat electrical cardioversion. However, significant pauses and risk for Torsades make Ibutilide less attractive for most practitioners. The transvenous electrodes or epicardial wires placed during surgery can be used for cardioversion or patient can be shocked by two pairs of external patch electrodes.

Rate control can be achieved with a variety of agents such as beta blockers including Metoprolol, Esmolol, Atenolol or Calcium channel antagonists like Diltiazem. Digoxin, Amiodarone or the newer agent Dronedarone are also popular choices at rate control. (48) Anticoagulation with warfarin is recommended if the AF is persisting for more than 48 hours. (32, 48) Heparin bridging is not recommended unless high risk features are present such as Mitral valve disease, prior stroke. (49) The criteria for anti coagulation per ESC are based on the CHADS2 – VASc score. Risk factors including increased Age > 75y and prior

Certain operative practices and techniques have shown to be of some benefit in reducing the incidence of POAF. Off pump surgery may decrease occurrence of AF, even when taking age into account. (42, 43) The anterior fat pad present in the mediastinum is considered to have parasympathetic nerves, which may play a role in initiating POAF. One study showed that preservation of the fat pad was protective but it could not be replicated in other studies. (44,45) Other factors include inducing hypothermia during Cardio Pulmonary Bypass

The only postoperative preventative measure may be early reinitiation of beta blockers and ACE-inhibitors. (13) There was a suggestion in a recent study that early statin use post

If AF does occur and is persistent despite the prophylactic measures, treatment should be initiated. There are two general approaches to AF treatment, Rate control or Rhythm control with both being acceptable as to preferred outcomes. (47) Whatever approach is taken, initial efforts need to be made to try and correct any obvious precipitating or co-existent mitigating factors. Meticulous attention needs to be paid to pain control, volume status, electrolyte balance, correcting anemia and hypoxia. Anticoagulation needs to be initiated as

Rhythm control where in AF is converted to sinus rhythm is preferred when the patient is deemed unstable such as if there is hypotension, ongoing ischemia, co-existing heart failure, if pre excitation is suspected or if the patient is very symptomatic. It is also preferred if anticoagulation is not an option for any reason. Rhythm control can be achieved either with pharmacological cardioversion or electrical cardioversion. Various anti arrhythmic agents can be used to convert AF, Amiodarone is typically preferred, because it can be transitioned to oral route, has comparatively lower proarrhythmic potential and may be better at ventricular rate control. Also as most patients have some underlying left ventricular dysfunction or coronary artery disease, Amiodarone is a safer choice in such patients. It is usually given as an initial bolus at 5 mg/Kg body weight over 30 minutes and then continued as an infusion at a dose of 25 mg /Hr. Various other pharmacological rhythm control agents used include

Direct current (DC) cardioversion is a quick and safe way to attempt rhythm control. Initial shock is attempted at 100 - 200 joules with synchronization when monophasic waveforms are used and 50 – 100 joules when biphasic waveforms are used. As usually the POAF has been present only for a short time DC cardioversion can successfully convert the AF to sinus in up to 95% of the cases. If it is not successful, intra venous Ibutilide can be given before repeat electrical cardioversion. However, significant pauses and risk for Torsades make Ibutilide less attractive for most practitioners. The transvenous electrodes or epicardial wires placed during surgery can be used for cardioversion or patient can be shocked by two pairs

Rate control can be achieved with a variety of agents such as beta blockers including Metoprolol, Esmolol, Atenolol or Calcium channel antagonists like Diltiazem. Digoxin, Amiodarone or the newer agent Dronedarone are also popular choices at rate control. (48) Anticoagulation with warfarin is recommended if the AF is persisting for more than 48 hours. (32, 48) Heparin bridging is not recommended unless high risk features are present such as Mitral valve disease, prior stroke. (49) The criteria for anti coagulation per ESC are based on the CHADS2 – VASc score. Risk factors including increased Age > 75y and prior

(CPB), using posterior pericardiotomy and Heparin coated CPB circuit etc. (27)

operatively may be beneficial in preventing POAF after cardiac surgery as well. (46)

**Intraoperative measures:** 

**Postoperative measures:** 

of external patch electrodes.

well if the AF is persistent for more than 48 hours.

Disopyramide, Procainamide, Flecainide, Ibutilide and Dofetilide. (10)

Stroke, transient ischemic attack (TIA) or thrombo embolism are given 2 points each. Factors including Hypertension, Congestive heart failure, Diabetes, Ages 65-74y, female Sex and co existent Vascular disease are scored 1 point each. Anticoagulation is indicated if the combined score is > 2. (48) Newer agents like Dabigatran are available on the market but studies will need to be done to assess its value specifically in the postoperative period.

Not much significant data is available as to the management of patients after discharge. They are usually reassessed 4-6 weeks after discharge and often times Holter monitoring is employed. Most of the patients can stop their anti arrhythmic medications and anti coagulation if they are deemed to be in sinus rhythm without intermittent AF, 3-6 months after hospital discharge.

In spite of all studies and evidence regarding preventing and treating POAF, doubts still exist whether any real benefit is obtained. Some evidence suggests that AF prevention does not or only minimally reduces the length of stay or the overall cost. (50) It is also noted that there is no actual decrease in the stroke incidence post operatively even if the AF is suppressed. It is unclear if the mortality and morbidity are improved if the AF is indeed suppressed. (51) It seems that stroke may be an epiphenomenon and not directly related to the occurrence of POAF. However a large Meta analysis does seem to suggest some overall benefit with prophylaxis measures and prevention of POAF. (52)
