Method: Single center, prospective, non-randomized, unblinded case series of all patients presenting with a cardiac arrest. The proposed study will collect data on all comatose patients presenting with cardiac arrest. The primary end point is death from any cause at 30 days from admission.

Significance: Develop criteria to guide an invasive strategy for comatose patients presenting with cardiac arrest, and so avoid ineffective or even futile therapy which carry its own significant risks for patients in the future. The criteria, in turn, can serve as the basis for a prospective, randomized trial in the future.

Research Design and Methods:

General Approach: This study is a prospective, non-randomized, unblinded case series of comatose patients presenting with cardiac arrest to either Essentia East (St. Mary's Medical Center or Miller-Dwan Medical Center) or Essentia West (Innovis Health).

Methods and Materials: Patients will be enrolled over a 60-month period by the PI, Sub-I, or study coordinator. The enrollment goal is 100 patients. The study will collect demographic, clinical and outcome data on comatose patients presenting with cardiac arrest only, and does not prescribe any clinical testing or therapies including PCI or hypothermia. All clinical decisions are left to the discretion of the attending providers.

Consent Process: This study will seek a waiver for informed consent as the patients, by study inclusion criteria, will not be able to provide informed consent, and this study uses a minimal risk design. In the spirit of transparency, attempts will be made to inform the patient, patient representative or family when possible of enrollment in the study within 48 hours of enrollment. The patient or appropriate patient representative identified from the EMR will be spoke to in person or by phone by the PI, sub-PI, or study coordinator.21 The patient and/or family will then have the opportunity to decline participation in the study. The conversation will be documented in the medical record by the PI, sub-PI or study coordinator.

Randomization Process: The study is a prospective, non-randomized, unblinded case series. Patient will be followed as a single cohort, and no randomization is required.

Study Endpoints:

Primary Endpoint:

• Death from any cause at 30 days from admission.

Secondary Endpoints:

• Death from any cause at 30 days from admission stratified by SCAI22 score
• Death from any cause at 30 days from admission stratified by presence or absence of PCI
• Neurological status at time of discharge using the Glasgow-Pittsburgh Cerebral-Perfusion Categories23,24

Observational and Data Collection:

Demographic and clinical data will be collected by a study investigator or study coordinator within 24 hours of admission. Potential candidates for participation will be identified by the PI, sub-PI, or study coordinator every morning by contacting the attending critical care or cardiology attending physicians every morning. Once identified, the study PI, sub-PI, or study coordinator will begin the chart review for data collection. Diagnostic and therapeutic management is left to the discretion of the attending providers. The protocol mandates no evaluation or therapies outside the usual practice of the attending providers. Baseline Demographic data will include:

Date of birth/Age Gender LVEF prior to admission Presence or absence of coronary artery disease Presence or absence of Comorbidities including COPD, diabetes, renal failure active malignancy, dementia, anemia Presence of congestive Presence of angina and CCS functional class heart failure and prior to admission NYHA functional Ethnicity class prior to admission

Baseline Clinical Variables that will be obtained include:25

Vitals signs on presentation to receiving facility including blood pressure, heart rate, respiratory rate, weight, height Witnessed or unwitnessed arrest Presence or absence of bystander CPR Resuscitation attempted by trained emergency personnel prior arrival at initial facility (receiving or transferring) Initial Rhythm prior to ROSC (for a pulseless arrest, the initial rhythm when the AED is placed) Therapies applied during resuscitation including CPR, defibrillation, medications, intubation Estimated time from initial arrest to initial ROSC Initial electrocardiogram characteristics including presence or absence of ST elevation, rhythm, corrected QT interval, QRS width Initial perfusing rhythm following resuscitation Time from arrival of medical personnel at scene of arrest to arrival at receiving facility. If the patient is brought to the receiving facility by someone other than medical personnel, then time is set to 0. Time to arrival to referral center from receiving facility. If referral center is also the receiving facility, then the time is set to 0. Time to arrival from receiving facility to intensive care unit or cath lab if the cath lab precedes the ICU Time to arrival to cath lab from the receiving facility Presence or absence of significance obstructive lesions and list of involved vessels if patient undergoes coronary angiography during hospitalization PCI performed and vessels treated if patient undergoes PCI during hospitalization Presence of absence of any ST elevation on an electrocardiogram within 24 hours of admission to referral facility Any use of mechanical support within 24 hours of admission to referral facility Any use of therapeutic cooling within 24 hours of admission to referral facility Any use of vasopressor agents within 24 hours of admission to referral facility Admission hemoglobin, creatine, and cardiac troponin, bicarbonate, pH, pO2 Glasgow Coma Score Presence or absence of cardiogenic shock within 24 hours of admission to referral facility Left Ventricular Ejection Fraction determined during the hospitalization and Closest to the time of death or discharge

During the clinical stay, pertinence clinical data will be collected including recurrent cardiac arrests, need for coronary angiography or revascularization more than 24 hours from admission, or implantation of an implantable cardioverter-defibrillator prior to discharge. Other significant clinical events will also be recorded including need for transfusion or other surgeries. A SCAI risk score22 will be calculated from the collected data by a study investigator or coordinator within 24 hours of admission. If the patient dies prior to discharge, the date and cause of death will be noted. Transfer to hospice or referral for comfort care will be recorded. If the patient is discharged alive, a Glasgow-Pittsburgh Cerebral Perfusion Category as a measurement of neurological function at time of discharge will be assessed. Disposition site (home, hospice, skilled nursing facility, or transfer to higher level of care) will be recorded. Thirty day follow-up will be performed by review of the medical record, review of public death records, or phone call as appropriate to assess vital status. If a recorded height or weight is not available within the first 24 hours, then estimations by either the staff caring for the patient or study coordinator may be used. The study will only collect data and will not include interaction with subjects.

Inclusion Criteria:

1. Age greater than or equal to 18 years
2. Presumed cardiac etiology of arrest
3. GCS ≤ 819,20
4. Initial presentation to an outside facility or to the emergency room of the receiving facility.

Exclusion Criteria:

1. Presumed non-cardiac etiology of arrest including trauma, pulmonary embolus, sepsis, respiratory failure.
2. GCS > 9
3. Transfer time from arrest to receiving facility greater than 12 hours
4. Cardiac arrest occurring after admission to either the outside facility or receiving facility.
5. Patient pronounced dead prior to arrival to the receiving facility emergency room.

Comatose patients presenting with cardiac arrest to the receiving facility within 12 hours of the event