NCT03779841

Inclusion Criteria:

Inclusion Criteria:

- Capable of giving signed informed consent, which includes compliance with the
requirements and restrictions listed in the informed consent form.

- Written informed consent from the participant has been obtained prior to any
study-related procedures

- Written documentation has been obtained in accordance with the relevant country and
local privacy requirements, where applicable (eg. Written Authorization for Use and
Release of Health and Research Study Information [US sites] and written Data
Protection consent (European Union sites).

- Participants who are scheduled to undergo open-chest cardiac surgery. Includes:
coronary artery bypass graft (CABG) and/or valve repair/replacement. Inclusionary
valve repair/replacement procedures for the primary reason for surgery include: Aortic
valve repair/replacement, Mitral valve repair/replacement, Combination of aortic and
tricuspid valve repair/replacement, Combination of mitral and tricuspid valve
repair/replacement CABG/valve combination procedures (when valvular procedure is one
of the 4 sub-bulleted procedures immediately above), Left Atrial Appendage (LAA)
procedures are allowed if CABG and/or valve repair or replacement is the qualifying
surgical procedure, but is not a qualifying surgical procedure on its own.

- A male participant must agree to use contraception until Day 60 and refrain from
donating sperm during this period.

- A female participant is eligible to participate if she is not pregnant (has a negative
urine pregnancy result prior to randomization) not breastfeeding, and at least 1 of
the following conditions applies: Not a woman of childbearing potential (WOCBP). A
WOCBP who agrees to follow the contraceptive guidance until after Day 60.

- In sinus rhythm for the last 48 hours prior to randomization based on standard-of care
assessments and study ECGs (note: continuous ECG monitoring for 48 hours is not
required; prior history of paroxysmal AF is acceptable)

- Willing to wear an electrocardiogram (ECG) patch for a full 30 days post-surgery and
for 7 days after each study visit

- Able, as assessed by the investigator, and willing to follow study instructions and
likely to complete required study visit.

Exclusion Criteria:

- Any uncontrolled clinically significant medical condition other than the one under
study that, in the investigator's opinion, would put the participant at an
unacceptable risk with exposure to botulinum toxin type A.

- Exclusionary valve repair/replacement procedures include: Combination of aortic and
mitral valve repair/replacement, Isolated tricuspid valve repair/replacement.

- Any medical condition that may put the participant at increased risk with exposure to
botulinum toxin type A, including diagnosed muscular dystrophy (eg, Duchenne's
muscular dystrophy), myasthenia gravis, Eaton-Lambert syndrome, amyotrophic lateral
sclerosis, mitochondrial disease, or any other significant disease which might
interfere with neuromuscular function.

- Participants with presence or history of any of the following within 3 months prior to
the Day 1 visit that may indicate a vulnerable respiratory state per the
investigator's clinical judgment: aspiration pneumonia, lower respiratory tract
infections, uncontrolled asthma, severe chronic obstructive pulmonary disease, or
otherwise compromised respiratory function.

- Permanent/persistent atrial fibrillation (AF)

- Has a known allergy or sensitivity to any botulinum toxin type A preparation. - Has a
known allergy or sensitivity to medical adhesive (eg, ECG patch adhesive;
hydrogel-based adhesive).

- Severe (> 55 mm left atrial diameter) left atrial enlargement

- Left ventricular ejection fraction (LVEF) < 25%

- Presence or history of symptomatic atrioventricular block > 1st degree within the last
30 days (note: presence of a pacemaker is not exclusionary per se) - Class I or III
antiarrhythmic drugs unless proper washout was documented

- Botulinum toxin type A (of any serotype) use within 6 months of randomization

- Has been immunized for any botulinum toxin type A serotype as determined by
participant medical history

- Preoperative need for inotropes/vasopressors or intra-aortic balloon pump

- Prior open-chest, sternotomy cardiac surgery - History of ablation for AF

- Planned ablation procedure for AF at the time of surgery

- Emergency surgery

- Current enrollment in an investigational drug or device study or participation in such
a study within 30 days of entry into this study

- Participants have diagnostic assessments which in the opinion of the investigator
prevent participation in the study

- Impaired prognosis defined as EuroSCORE II > 7% perioperative mortality at screening
is exclusionary.

- Females who are pregnant, nursing, or planning a pregnancy during the study

- The participant has a condition or is in a situation which, in the investigator's
opinion, may put the participant at significant risk, may confound the study results,
or may interfere significantly with the participant's participation in the study.