Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.

Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.

Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.

Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.

Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.

Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.

Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.

Patients randomized to this arm will be treated with an initial strategy of rate control. The target heart rate is < 100 beats per minute at rest. The treating clinician will choose agents from the list of rate control medications below and employ these medications (singly or in combination) to achieve rate control. A patient who presents with AF and slow ventricular response rate (<60 beats per minute) may still be randomized to the rate control strategy; in such instances, rate control agents may be withheld or administered in low doses. Dose ranges, as defined in guidelines, for each of the rate control agents need to be adhered to. Simultaneous use of more than one of the categories of rate control agents should be done with caution due to risk of bradycardia.

Rate Control Agents:

Beta blockers (e.g. metoprolol, atenolol, carvedilol, esmolol) Calcium channel blockers (nondihydropyridine) (e.g. diltiazem, verapamil) Digoxin

Patients assigned to an initial strategy of rhythm control will be treated with amiodarone alone or amiodarone plus direct current (DC) cardioversion if amiodarone alone does not eliminate AF within 48 hours. For patients who are hemodynamically stable but remain in AF, at least 24 hours of amiodarone should be administered before cardioversion is attempted. Cardioversion should be attempted, if possible, prior to the 48 hour duration to avoid the need for a TEE guided approach.

If AF has been present for ≥ 48 hours and the patient has not been therapeutically anticoagulated, cardioversion should be TEE guided. When deemed to be clinically appropriate, patients in the rhythm control arm may also be treated with a rate control medication (e.g. beta blocker). In particular, a rate control medication may be indicated at the onset of AF.